v0.10.0 of typeahead.js ended up being almost a complete rewrite. Many things stayed the same, but there were a handful of changes you need to be aware of if you plan on upgrading from an older version. This document aims to call out those changes and explain what you need to do in order to have an painless upgrade.
In v0.10.0, the first argument to jQuery#typeahead
is an options hash that
can be used to configure the behavior of the typeahead. This is in contrast
to previous versions where jQuery#typeahead
expected just a series of datasets
to be passed to it:
```javascript // pre-v0.10.0 $(‘.typeahead’).typeahead(myDataset);
// v0.10.0 $(‘.typeahead’).typeahead({ highlight: true, hint: false }, myDataset); ```
If you’re fine with the default configuration, you can just pass null
as the
first argument:
javascript
$('.typeahead').typeahead(null, myDataset);
The most notable change in v0.10.0 is that typeahead.js has been decomposed into a suggestion engine and a UI view. As part of this change, the way you configure datasets has changed. Previously, a dataset config would have looked like:
javascript
{
valueKey: 'num',
local: [{ num: 'one' }, { num: 'two' }, { num: 'three' }],
prefetch: '/prefetch',
remote: '/remote?q=%QUERY'
}
In v0.10.0, an equivalent dataset config would look like:
javascript
{
displayKey: 'num',
source: mySource
}
As you can see, local
, prefetch
, and remote
are no longer defined at the
dataset level. Instead, all you set in a dataset config is source
. source
is
expected to be a function with the signature function(query, callback)
. When a
typeahead’s query changes, suggestions will be requested from source
. It’s
expected source
will compute the suggestion set and invoke callback
with an array
of suggestion objects. The typeahead will then go on to render those suggestions.
If you’re wondering if you can still configure local
, prefetch
, and
remote
, don’t worry, that’s where the Bloodhound suggestion engine comes in.
Here’s how you would define mySource
which was referenced in the previous
code snippet:
``` var mySource = new Bloodhound({ datumTokenizer: function(d) { return Bloodhound.tokenizers.whitespace(d.num); }, queryTokenizer: Bloodhound.tokenizers.whitespace, local: [{ num: ‘one’ }, { num: ‘two’ }, { num: ‘three’ }], prefetch: ‘/prefetch’, remote: ‘/remote?q=%QUERY’ });
// this kicks off the loading and processing of local and prefetch data // the suggestion engine will be useless until it is initialized mySource.initialize(); ```
In the above snippet, a Bloodhound suggestion engine is initialized and that’s
what will be used as the source of your dataset. There’s still one last thing
that needs to be done before you can use a Bloodhound suggestion engine as the
source of a dataset. Because datasets expect source
to be function, the
Bloodhound instance needs to be wrapped in an adapter so it can meet that
expectation.
mySource = mySource.ttAdapter();
Put it all together:
```javascript var mySource = new Bloodhound({ datumTokenizer: function(d) { return Bloodhound.tokenizers.whitespace(d.num); }, queryTokenizer: Bloodhound.tokenizers.whitespace, local: [{ num: ‘one’ }, { num: ‘two’ }, { num: ‘three’ }], prefetch: ‘/prefetch’, remote: ‘/remote?q=%QUERY’ });
mySource.initialize();
$(‘.typeahead’).typeahead(null, { displayKey: ‘num’, source: mySource.ttAdapter() }); ```
The Bloodhound suggestion engine is token-based, so how datums and queries are tokenized plays a vital role in the quality of search results. Pre-v0.10.0, it was not possible to configure the tokenization method. Starting in v0.10.0, you must specify how you want datums and queries tokenized.
The most common tokenization methods split a given string on whitespace or non-word characters. Bloodhound provides implementations for those methods out of the box:
```javascript // returns [‘one’, ‘two’, ‘twenty-five’] Bloodhound.tokenizers.whitespace(‘ one two twenty-five’);
// returns [‘one’, ‘two’, ‘twenty’, ‘five’] Bloodhound.tokenizers.nonword(‘ one two twenty-five’); ```
For query tokenization, you’ll probably want to use one of the above methods. For datum tokenization, this is where you may want to do something a tad bit more advanced.
For datums, sometimes you want tokens to be dervied from more than one property. For example, if you were building a search engine for GitHub repositories, it’d probably be wise to have tokens derived from the repo’s name, owner, and primary language:
```javascript var repos = [ { name: ‘example’, owner: ‘John Doe’, language: ‘JavaScript’ }, { name: ‘another example’, owner: ‘Joe Doe’, language: ‘Scala’ } ];
function customTokenizer(datum) { var nameTokens = Bloodhound.tokenizers.whitespace(datum.name); var ownerTokens = Bloodhound.tokenizers.whitespace(datum.owner); var languageTokens = Bloodhound.tokenizers.whitespace(datum.language);
return nameTokens.concat(ownerTokens).concat(languageTokens); } ```
There may also be the scenario where you want datum tokenization to be performed on the backend. The best way to do that is to just add a property to your datums that contains those tokens. You can then provide a tokenizer that just returns the already existing tokens:
```javascript var sports = [ { value: ‘football’, tokens: [‘football’, ‘pigskin’] }, { value: ‘basketball’, tokens: [‘basketball’, ‘bball’] } ];
function customTokenizer(datum) { return datum.tokens; } ```
There are plenty of other ways you could go about tokenizing datums, it really just depends on what you are trying to accomplish.
Dropping support for string datums was a difficult choice, but in the end it
made sense for a number of reasons. If you still want to hydrate the suggestion
engine with string datums, you’ll need to use the filter
function:
javascript
var engine = new Bloodhound({
prefetch: {
url: '/data',
filter: function(data) {
// assume data is an array of strings e.g. ['one', 'two', 'three']
return $.map(data, function(str) { return { value: str }; });
},
datumTokenizer: function(d) {
return Bloodhound.tokenizers.whitespace(d.value);
},
queryTokenizer: Bloodhound.tokenizers.whitespace
}
});
In previous versions of typeahead.js, you could specify a string template along with the templating engine that should be used to compile/render it. In v0.10.0, you can no longer specify templating engines; instead you must provide precompiled templates. Precompiled templates are functions that take one argument: the context the template should be rendered with.
Most of the popular templating engines allow for the creation of precompiled templates. For example, you can generate one using Handlebars by doing the following:
javascript
var precompiledTemplate = Handlebars.compile('<p>{{value}}</p>');
tt-is-under-cursor
is now tt-cursor
- Applied to a hovered-on suggestion (either via cursor or arrow key).
tt-query
is now tt-input
- Applied to the typeahead input field.
If something is missing from this migration guide, pull requests are accepted :)


--- layout: page title: "Full-stack web developer Craig MacGregor, from Toronto, Canada" date: 2013-08-16 23:48 comments: true show_title: false sidebar: false hero_unit: true is_homepage: true ---
This is my bread and butter. Anything from creating an MVP, building a mobile experience, or API creation/integration, this is where I feel most at home.
Need some advice on your next project? I'm here to help you with any technical issues or concerns you may have.
Great execution is at the heart of any successful project. Using modern, agile techniques and quick feedback loops I can build and execute a plan of attack successfully.


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This document describes the syntax and semantics of the template engine and will be most useful as reference to those creating Jinja templates. As the template engine is very flexible the configuration from the application might be slightly different from here in terms of delimiters and behavior of undefined values.
A template is simply a text file. It can generate any text-based format (HTML, XML, CSV, LaTeX, etc.). It doesn’t have a specific extension, .html or .xml are just fine.
A template contains variables or expressions, which get replaced with values when the template is evaluated, and tags, which control the logic of the template. The template syntax is heavily inspired by Django and Python.
Below is a minimal template that illustrates a few basics. We will cover the details later in that document:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">

<title>My Webpage</title>

{% for item in navigation %}

{{ item.caption }}

{% endfor %}

My Webpage

{{ a_variable }}

This covers the default settings. The application developer might have changed the syntax from {% foo %} to <% foo %> or something similar.
There are two kinds of delimiters. {% ... %} and {{ ... }}. The first one is used to execute statements such as for-loops or assign values, the latter prints the result of the expression to the template.
The application passes variables to the templates you can mess around in the template. Variables may have attributes or elements on them you can access too. How a variable looks like, heavily depends on the application providing those.
You can use a dot (.) to access attributes of a variable, alternative the so-called “subscript” syntax ([]) can be used. The following lines do the same:
{{ foo.bar }}
{{ foo['bar'] }}
It’s important to know that the curly braces are not part of the variable but the print statement. If you access variables inside tags don’t put the braces around.
If a variable or attribute does not exist you will get back an undefined value. What you can do with that kind of value depends on the application configuration, the default behavior is that it evaluates to an empty string if printed and that you can iterate over it, but every other operation fails.
Implementation
For convenience sake foo.bar in Jinja2 does the following things on the Python layer:
foo['bar'] on the other hand works mostly the same with the a small difference in the order:
This is important if an object has an item or attribute with the same name. Additionally there is the attr() filter that just looks up attributes.
Variables can be modified by filters. Filters are separated from the variable by a pipe symbol (|) and may have optional arguments in parentheses. Multiple filters can be chained. The output of one filter is applied to the next.
{{ name|striptags|title }} for example will remove all HTML Tags from the name and title-cases it. Filters that accept arguments have parentheses around the arguments, like a function call. This example will join a list by commas: {{ list|join(', ') }}.
The List of Builtin Filters below describes all the builtin filters.
Beside filters there are also so called “tests” available. Tests can be used to test a variable against a common expression. To test a variable or expression you add is plus the name of the test after the variable. For example to find out if a variable is defined you can do name is defined which will then return true or false depending on if name is defined.
Tests can accept arguments too. If the test only takes one argument you can leave out the parentheses to group them. For example the following two expressions do the same:
{% if loop.index is divisibleby 3 %}
{% if loop.index is divisibleby(3) %}
The List of Builtin Tests below describes all the builtin tests.
To comment-out part of a line in a template, use the comment syntax which is by default set to {# ... #}. This is useful to comment out parts of the template for debugging or to add information for other template designers or yourself:
{# note: disabled template because we no longer use this
{% for user in users %}
...
{% endfor %}
#}
In the default configuration, a single trailing newline is stripped if present, and whitespace is not further modified by the template engine. Each whitespace (spaces, tabs, newlines etc.) is returned unchanged. If the application configures Jinja to trim_blocks the first newline after a template tag is removed automatically (like in PHP). The lstrip_blocks option can also be set to strip tabs and spaces from the beginning of line to the start of a block. (Nothing will be stripped if there are other characters before the start of the block.)
With both trim_blocks and lstrip_blocks enabled you can put block tags on their own lines, and the entire block line will be removed when rendered, preserving the whitespace of the contents. For example, without the trim_blocks and lstrip_blocks options, this template:

{% if True %}
yay
{% endif %}

gets rendered with blank lines inside the div:

yay

But with both trim_blocks and lstrip_blocks enabled, the lines with the template blocks are removed while preserving the whitespace of the contents:

yay

You can manually disable the lstrip_blocks behavior by putting a plus sign (+) at the start of a block:

{%+ if something %}yay{% endif %}

You can also strip whitespace in templates by hand. If you put an minus sign (-) to the start or end of an block (for example a for tag), a comment or variable expression you can remove the whitespaces after or before that block:
{% for item in seq -%}
{{ item }}
{%- endfor %}
This will yield all elements without whitespace between them. If seq was a list of numbers from 1 to 9 the output would be 123456789.
If Line Statements are enabled they strip leading whitespace automatically up to the beginning of the line.
Jinja2 by default also removes trailing newlines. To keep the single trailing newline when it is present, configure Jinja to keep_trailing_newline.
Note
You must not use a whitespace between the tag and the minus sign.
valid:
{%- if foo -%}...{% endif %}
invalid:
{% - if foo - %}...{% endif %}
It is sometimes desirable or even necessary to have Jinja ignore parts it would otherwise handle as variables or blocks. For example if the default syntax is used and you want to use {{ as raw string in the template and not start a variable you have to use a trick.
The easiest way is to output the variable delimiter ({{) by using a variable expression:
{{ '{{' }}
For bigger sections it makes sense to mark a block raw. For example to put Jinja syntax as example into a template you can use this snippet:
{% raw %}

{% for item in seq %}

{{ item }}

{% endfor %}

{% endraw %}
If line statements are enabled by the application it’s possible to mark a line as a statement. For example if the line statement prefix is configured to # the following two examples are equivalent:

# for item in seq

{{ item }}

# endfor

{% for item in seq %}

{{ item }}

{% endfor %}

The line statement prefix can appear anywhere on the line as long as no text precedes it. For better readability statements that start a block (such as for, if, elif etc.) may end with a colon:
# for item in seq:
...
# endfor
Note
Line statements can span multiple lines if there are open parentheses, braces or brackets:

# for href, caption in [('index.html', 'Index'),
('about.html', 'About')]:

{{ caption }}

# endfor

Since Jinja 2.2 line-based comments are available as well. For example if the line-comment prefix is configured to be ## everything from ## to the end of the line is ignored (excluding the newline sign):
# for item in seq:

{{ item }}
 ## this comment is ignored
# endfor
The most powerful part of Jinja is template inheritance. Template inheritance allows you to build a base “skeleton” template that contains all the common elements of your site and defines blocks that child templates can override.
Sounds complicated but is very basic. It’s easiest to understand it by starting with an example.
This template, which we’ll call base.html, defines a simple HTML skeleton document that you might use for a simple two-column page. It’s the job of “child” templates to fill the empty blocks with content:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">

{% block head %}
<link rel="stylesheet" href="style.css" />
<title>{% block title %}{% endblock %} - My Webpage</title>
{% endblock %}

{% block content %}{% endblock %}

{% block footer %}
© Copyright 2008 by you.
{% endblock %}

In this example, the {% block %} tags define four blocks that child templates can fill in. All the block tag does is to tell the template engine that a child template may override those portions of the template.
A child template might look like this:
{% extends "base.html" %}
{% block title %}Index{% endblock %}
{% block head %}
{{ super() }}

{% endblock %}
{% block content %}

Index

Welcome on my awesome homepage.

{% endblock %}
The {% extends %} tag is the key here. It tells the template engine that this template “extends” another template. When the template system evaluates this template, first it locates the parent. The extends tag should be the first tag in the template. Everything before it is printed out normally and may cause confusion. For details about this behavior and how to take advantage of it, see Null-Master Fallback.
The filename of the template depends on the template loader. For example the FileSystemLoader allows you to access other templates by giving the filename. You can access templates in subdirectories with a slash:
{% extends "layout/default.html" %}
But this behavior can depend on the application embedding Jinja. Note that since the child template doesn’t define the footer block, the value from the parent template is used instead.
You can’t define multiple {% block %} tags with the same name in the same template. This limitation exists because a block tag works in “both” directions. That is, a block tag doesn’t just provide a hole to fill - it also defines the content that fills the hole in the parent. If there were two similarly-named {% block %} tags in a template, that template’s parent wouldn’t know which one of the blocks’ content to use.
If you want to print a block multiple times you can however use the special self variable and call the block with that name:
<title>{% block title %}{% endblock %}</title>

{{ self.title() }}

{% block body %}{% endblock %}
It’s possible to render the contents of the parent block by calling super. This gives back the results of the parent block:
{% block sidebar %}

Table Of Contents

...
{{ super() }}
{% endblock %}
Jinja2 allows you to put the name of the block after the end tag for better readability:
{% block sidebar %}
{% block inner_sidebar %}
...
{% endblock inner_sidebar %}
{% endblock sidebar %}
However the name after the endblock word must match the block name.
Blocks can be nested for more complex layouts. However per default blocks may not access variables from outer scopes:
{% for item in seq %}

{% block loop_item %}{{ item }}{% endblock %}

{% endfor %}
This example would output empty
 items because item is unavailable inside the block. The reason for this is that if the block is replaced by a child template a variable would appear that was not defined in the block or passed to the context.
Starting with Jinja 2.2 you can explicitly specify that variables are available in a block by setting the block to “scoped” by adding the scoped modifier to a block declaration:
{% for item in seq %}

{% block loop_item scoped %}{{ item }}{% endblock %}

{% endfor %}
When overriding a block the scoped modifier does not have to be provided.
Changed in version 2.4.
If a template object was passed to the template context you can extend from that object as well. Assuming the calling code passes a layout template as layout_template to the environment, this code works:
{% extends layout_template %}
Previously the layout_template variable had to be a string with the layout template’s filename for this to work.
When generating HTML from templates, there’s always a risk that a variable will include characters that affect the resulting HTML. There are two approaches: manually escaping each variable or automatically escaping everything by default.
Jinja supports both, but what is used depends on the application configuration. The default configuaration is no automatic escaping for various reasons:
If manual escaping is enabled it’s your responsibility to escape variables if needed. What to escape? If you have a variable that may include any of the following chars (>, <, &, or ") you have to escape it unless the variable contains well-formed and trusted HTML. Escaping works by piping the variable through the |e filter: {{ user.username|e }}.
When automatic escaping is enabled everything is escaped by default except for values explicitly marked as safe. Those can either be marked by the application or in the template by using the |safe filter. The main problem with this approach is that Python itself doesn’t have the concept of tainted values so the information if a value is safe or unsafe can get lost. If the information is lost escaping will take place which means that you could end up with double escaped contents.
Double escaping is easy to avoid however, just rely on the tools Jinja2 provides and don’t use builtin Python constructs such as the string modulo operator.
Functions returning template data (macros, super, self.BLOCKNAME) return safe markup always.
String literals in templates with automatic escaping are considered unsafe too. The reason for this is that the safe string is an extension to Python and not every library will work properly with it.
A control structure refers to all those things that control the flow of a program - conditionals (i.e. if/elif/else), for-loops, as well as things like macros and blocks. Control structures appear inside {% ... %} blocks in the default syntax.
Loop over each item in a sequence. For example, to display a list of users provided in a variable called users:

Members

{% for user in users %}

{{ user.username|e }}

{% endfor %}

As variables in templates retain their object properties, it is possible to iterate over containers like dict:

{% for key, value in my_dict.iteritems() %}

{{ key|e }}

{{ value|e }}

{% endfor %}

Note however that dictionaries usually are unordered so you might want to either pass it as a sorted list to the template or use the dictsort filter.
Inside of a for-loop block you can access some special variables:
| Variable | Description |
|---|---|
| loop.index | The current iteration of the loop. (1 indexed) |
| loop.index0 | The current iteration of the loop. (0 indexed) |
| loop.revindex | The number of iterations from the end of the loop (1 indexed) |
| loop.revindex0 | The number of iterations from the end of the loop (0 indexed) |
| loop.first | True if first iteration. |
| loop.last | True if last iteration. |
| loop.length | The number of items in the sequence. |
| loop.cycle | A helper function to cycle between a list of sequences. See the explanation below. |
| loop.depth | Indicates how deep in deep in a recursive loop the rendering currently is. Starts at level 1 |
| `loop.depth0 | Indicates how deep in deep in a recursive loop the rendering currently is. Starts at level 0 |
Within a for-loop, it’s possible to cycle among a list of strings/variables each time through the loop by using the special loop.cycle helper:
{% for row in rows %}

{{ row }}

{% endfor %}
Since Jinja 2.1 an extra cycle helper exists that allows loop-unbound cycling. For more information have a look at the List of Global Functions.
Unlike in Python it’s not possible to break or continue in a loop. You can however filter the sequence during iteration which allows you to skip items. The following example skips all the users which are hidden:
{% for user in users if not user.hidden %}

{{ user.username|e }}

{% endfor %}
The advantage is that the special loop variable will count correctly thus not counting the users not iterated over.
If no iteration took place because the sequence was empty or the filtering removed all the items from the sequence you can render a replacement block by using else:

{% for user in users %}

{{ user.username|e }}

{% else %}

no users found

{% endfor %}

Note that in Python else blocks are executed whenever the corresponding loop did not break. Since in Jinja loops cannot break anyway, a slightly different behavior of the else keyword was chosen.
It is also possible to use loops recursively. This is useful if you are dealing with recursive data such as sitemaps. To use loops recursively you basically have to add the recursive modifier to the loop definition and call the loop variable with the new iterable where you want to recurse.
The following example implements a sitemap with recursive loops:

{%- for item in sitemap recursive %}

{{ item.title }}
{%- if item.children -%}

{{ loop(item.children) }}

{%- endif %}

{%- endfor %}

The loop variable always refers to the closest (innermost) loop. If we have more than one levels of loops, we can rebind the variable loop by writing {% set outer_loop = loop %} after the loop that we want to use recursively. Then, we can call it using {{ outer_loop(...) }}
The if statement in Jinja is comparable with the if statements of Python. In the simplest form you can use it to test if a variable is defined, not empty or not false:
{% if users %}

{% for user in users %}

{{ user.username|e }}

{% endfor %}

{% endif %}
For multiple branches elif and else can be used like in Python. You can use more complex Expressions there too:
{% if kenny.sick %}
Kenny is sick.
{% elif kenny.dead %}
You killed Kenny! You bastard!!!
{% else %}
Kenny looks okay --- so far
{% endif %}
If can also be used as inline expression and for loop filtering.
Macros are comparable with functions in regular programming languages. They are useful to put often used idioms into reusable functions to not repeat yourself.
Here a small example of a macro that renders a form element:
{% macro input(name, value='', type='text', size=20) -%}
<input type="{{ type }}" name="{{ name }}" value="{{
value|e }}" size="{{ size }}">
{%- endmacro %}
The macro can then be called like a function in the namespace:

{{ input('username') }}

{{ input('password', type='password') }}

If the macro was defined in a different template you have to import it first.
Inside macros you have access to three special variables:
Macros also expose some of their internal details. The following attributes are available on a macro object:
If a macro name starts with an underscore it’s not exported and can’t be imported.
In some cases it can be useful to pass a macro to another macro. For this purpose you can use the special call block. The following example shows a macro that takes advantage of the call functionality and how it can be used:
{% macro render_dialog(title, class='dialog') -%}

{{ title }}

{{ caller() }}

{%- endmacro %}
{% call render_dialog('Hello World') %}
This is a simple dialog rendered by using a macro and
a call block.
{% endcall %}
It’s also possible to pass arguments back to the call block. This makes it useful as replacement for loops. Generally speaking a call block works exactly like an macro, just that it doesn’t have a name.
Here an example of how a call block can be used with arguments:
{% macro dump_users(users) -%}

{%- for user in users %}

{{ user.username|e }}
{{ caller(user) }}

{%- endfor %}

{%- endmacro %}
{% call(user) dump_users(list_of_user) %}

Realname

{{ user.realname|e }}

Description

{{ user.description }}

{% endcall %}
Filter sections allow you to apply regular Jinja2 filters on a block of template data. Just wrap the code in the special filter section:
{% filter upper %}
This text becomes uppercase
{% endfilter %}
Inside code blocks you can also assign values to variables. Assignments at top level (outside of blocks, macros or loops) are exported from the template like top level macros and can be imported by other templates.
Assignments use the set tag and can have multiple targets:
{% set navigation = [('index.html', 'Index'), ('about.html', 'About')] %}
{% set key, value = call_something() %}
The extends tag can be used to extend a template from another one. You can have multiple of them in a file but only one of them may be executed at the time. See the section about Template Inheritance above.
Blocks are used for inheritance and act as placeholders and replacements at the same time. They are documented in detail as part of the section about Template Inheritance.
The include statement is useful to include a template and return the rendered contents of that file into the current namespace:
{% include 'header.html' %}
Body
{% include 'footer.html' %}
Included templates have access to the variables of the active context by default. For more details about context behavior of imports and includes see Import Context Behavior.
From Jinja 2.2 onwards you can mark an include with ignore missing in which case Jinja will ignore the statement if the template to be included does not exist. When combined with with or without context it has to be placed before the context visibility statement. Here some valid examples:
{% include "sidebar.html" ignore missing %}
{% include "sidebar.html" ignore missing with context %}
{% include "sidebar.html" ignore missing without context %}
New in version 2.2.
You can also provide a list of templates that are checked for existence before inclusion. The first template that exists will be included. If ignore missing is given, it will fall back to rendering nothing if none of the templates exist, otherwise it will raise an exception.
Example:
{% include ['page_detailed.html', 'page.html'] %}
{% include ['special_sidebar.html', 'sidebar.html'] ignore missing %}
Changed in version 2.4: If a template object was passed to the template context you can include that object using include.
Jinja2 supports putting often used code into macros. These macros can go into different templates and get imported from there. This works similar to the import statements in Python. It’s important to know that imports are cached and imported templates don’t have access to the current template variables, just the globals by default. For more details about context behavior of imports and includes see Import Context Behavior.
There are two ways to import templates. You can import the complete template into a variable or request specific macros / exported variables from it.
Imagine we have a helper module that renders forms (called forms.html):
{% macro input(name, value='', type='text') -%}
<input type="{{ type }}" value="{{ value|e }}" name="{{ name }}">
{%- endmacro %}
{%- macro textarea(name, value='', rows=10, cols=40) -%}
<textarea name="{{ name }}" rows="{{ rows }}" cols="{{ cols
}}">{{ value|e }}</textarea>
{%- endmacro %}
The easiest and most flexible is importing the whole module into a variable. That way you can access the attributes:
{% import 'forms.html' as forms %}

Username

{{ forms.input('username') }}

Password

{{ forms.input('password', type='password') }}

{{ forms.textarea('comment') }}

Alternatively you can import names from the template into the current namespace:
{% from 'forms.html' import input as input_field, textarea %}

Username

{{ input_field('username') }}

Password

{{ input_field('password', type='password') }}

{{ textarea('comment') }}

Macros and variables starting with one or more underscores are private and cannot be imported.
Changed in version 2.4: If a template object was passed to the template context you can import from that object.
Per default included templates are passed the current context and imported templates not. The reason for this is that imports unlike includes are cached as imports are often used just as a module that holds macros.
This however can be changed of course explicitly. By adding with context or without context to the import/include directive the current context can be passed to the template and caching is disabled automatically.
Here two examples:
{% from 'forms.html' import input with context %}
{% include 'header.html' without context %}
Note
In Jinja 2.0 the context that was passed to the included template did not include variables defined in the template. As a matter of fact this did not work:
{% for box in boxes %}
{% include "render_box.html" %}
{% endfor %}
The included template render_box.html is not able to access box in Jinja 2.0. As of Jinja 2.1 render_box.html is able to do so.
Jinja allows basic expressions everywhere. These work very similar to regular Python and even if you’re not working with Python you should feel comfortable with it.
The simplest form of expressions are literals. Literals are representations for Python objects such as strings and numbers. The following literals exist:
Everything between two brackets is a list. Lists are useful to store sequential data in or to iterate over them. For example you can easily create a list of links using lists and tuples with a for loop:

{% for href, caption in [('index.html', 'Index'), ('about.html', 'About'),
('downloads.html', 'Downloads')] %}

{{ caption }}

{% endfor %}

Note
The special constants true, false and none are indeed lowercase. Because that caused confusion in the past, when writing True expands to an undefined variable that is considered false, all three of them can be written in title case too (True, False, and None). However for consistency (all Jinja identifiers are lowercase) you should use the lowercase versions.
Jinja allows you to calculate with values. This is rarely useful in templates but exists for completeness’ sake. The following operators are supported:
For if statements, for filtering or if expressions it can be useful to combine multiple expressions:
Note
The is and in operators support negation using an infix notation too: foo is not bar and foo not in bar instead of not foo is bar and not foo in bar. All other expressions require a prefix notation: not (foo and bar).
The following operators are very useful but don’t fit into any of the other two categories:
It is also possible to use inline if expressions. These are useful in some situations. For example you can use this to extend from one template if a variable is defined, otherwise from the default layout template:
{% extends layout_template if layout_template is defined else 'master.html' %}
The general syntax is <do something> if <something is true> else <do something else>.
The else part is optional. If not provided the else block implicitly evaluates into an undefined object:
{{ '[%s]' % page.title if page.title }}
The following functions are available in the global scope by default:
Return a list containing an arithmetic progression of integers. range(i, j) returns [i, i+1, i+2, ..., j-1]; start (!) defaults to 0. When step is given, it specifies the increment (or decrement). For example, range(4) returns [0, 1, 2, 3]. The end point is omitted! These are exactly the valid indices for a list of 4 elements.
This is useful to repeat a template block multiple times for example to fill a list. Imagine you have 7 users in the list but you want to render three empty items to enforce a height with CSS:

{% for user in users %}

{{ user.username }}

{% endfor %}
{% for number in range(10 - users|count) %}

...

{% endfor %}

Generates some lorem ipsum for the template. Per default five paragraphs with HTML are generated each paragraph between 20 and 100 words. If html is disabled regular text is returned. This is useful to generate simple contents for layout testing.
A convenient alternative to dict literals. {'foo': 'bar'} is the same as dict(foo='bar').
The cycler allows you to cycle among values similar to how loop.cycle works. Unlike loop.cycle however you can use this cycler outside of loops or over multiple loops.
This is for example very useful if you want to show a list of folders and files, with the folders on top, but both in the same list with alternating row colors.
The following example shows how cycler can be used:
{% set row_class = cycler('odd', 'even') %}

{% for folder in folders %}

{{ folder|e }}

{% endfor %}
{% for filename in files %}

{{ filename|e }}

{% endfor %}

A cycler has the following attributes and methods:
Resets the cycle to the first item.
Goes one item a head and returns the then current item.
Returns the current item.
new in Jinja 2.1
A tiny helper that can be use to “join” multiple sections. A joiner is passed a string and will return that string every time it’s called, except the first time in which situation it returns an empty string. You can use this to join things:
{% set pipe = joiner("|") %}
{% if categories %} {{ pipe() }}
Categories: {{ categories|join(", ") }}
{% endif %}
{% if author %} {{ pipe() }}
Author: {{ author() }}
{% endif %}
{% if can_edit %} {{ pipe() }}
Edit
{% endif %}
new in Jinja 2.1
The following sections cover the built-in Jinja2 extensions that may be enabled by the application. The application could also provide further extensions not covered by this documentation. In that case there should be a separate document explaining the extensions.
If the i18n extension is enabled it’s possible to mark parts in the template as translatable. To mark a section as translatable you can use trans:

{% trans %}Hello {{ user }}!{% endtrans %}

To translate a template expression — say, using template filters or just accessing an attribute of an object — you need to bind the expression to a name for use within the translation block:

{% trans user=user.username %}Hello {{ user }}!{% endtrans %}

If you need to bind more than one expression inside a trans tag, separate the pieces with a comma (,):
{% trans book_title=book.title, author=author.name %}
This is {{ book_title }} by {{ author }}
{% endtrans %}
Inside trans tags no statements are allowed, only variable tags are.
To pluralize, specify both the singular and plural forms with the pluralize tag, which appears between trans and endtrans:
{% trans count=list|length %}
There is {{ count }} {{ name }} object.
{% pluralize %}
There are {{ count }} {{ name }} objects.
{% endtrans %}
Per default the first variable in a block is used to determine the correct singular or plural form. If that doesn’t work out you can specify the name which should be used for pluralizing by adding it as parameter to pluralize:
{% trans ..., user_count=users|length %}...
{% pluralize user_count %}...{% endtrans %}
It’s also possible to translate strings in expressions. For that purpose three functions exist:
_ gettext: translate a single string - ngettext: translate a pluralizable string - _: alias for gettext
For example you can print a translated string easily this way:
{{ _('Hello World!') }}
To use placeholders you can use the format filter:
{{ _('Hello %(user)s!')|format(user=user.username) }}
For multiple placeholders always use keyword arguments to format as other languages may not use the words in the same order.
Changed in version 2.5.
If newstyle gettext calls are activated (Newstyle Gettext), using placeholders is a lot easier:
{{ gettext('Hello World!') }}
{{ gettext('Hello %(name)s!', name='World') }}
{{ ngettext('%(num)d apple', '%(num)d apples', apples|count) }}
Note that the ngettext function’s format string automatically receives the count as num parameter additionally to the regular parameters.
If the expression-statement extension is loaded a tag called do is available that works exactly like the regular variable expression ({{ ... }}) just that it doesn’t print anything. This can be used to modify lists:
{% do navigation.append('a string') %}
If the application enables the Loop Controls it’s possible to use break and continue in loops. When break is reached, the loop is terminated; if continue is reached, the processing is stopped and continues with the next iteration.
Here a loop that skips every second item:
{% for user in users %}
{%- if loop.index is even %}{% continue %}{% endif %}
...
{% endfor %}
Likewise a look that stops processing after the 10th iteration:
{% for user in users %}
{%- if loop.index >= 10 %}{% break %}{% endif %}
{%- endfor %}
New in version 2.3.
If the application enables the With Statement it is possible to use the with keyword in templates. This makes it possible to create a new inner scope. Variables set within this scope are not visible outside of the scope.
With in a nutshell:
{% with %}
{% set foo = 42 %}
{{ foo }} foo is 42 here
{% endwith %}
foo is not visible here any longer
Because it is common to set variables at the beginning of the scope you can do that within the with statement. The following two examples are equivalent:
{% with foo = 42 %}
{{ foo }}
{% endwith %}
{% with %}
{% set foo = 42 %}
{{ foo }}
{% endwith %}
New in version 2.4.
If the application enables the Autoescape Extension one can activate and deactivate the autoescaping from within the templates.
Example:
{% autoescape true %}
Autoescaping is active within this block
{% endautoescape %}
{% autoescape false %}
Autoescaping is inactive within this block
{% endautoescape %}
After the endautoescape the behavior is reverted to what it was before.


{% extends "base.html" %} {% block title %}
Medieval catalogues > HENRY DE KIRKESTEDE > Catalogus, c. 1360
{% endif %}99 identified entries found.
All data was derived from the List of Identifications by Professor Richard Sharpe.
{% if not printing %}
A key to codes used in the List is available (opens in new tab).{% endif %}