Macros for Jinja or Jinja222.07.25

Macros

Macros are comparable with functions in regular programming languages. They are useful to put often used idioms into reusable functions to not repeat yourself (“DRY”).

Here’s 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:

<p>{{ input('username') }}</p>
<p>{{ input('password', type='password') }}</p>

If the macro was defined in a different template, you have to import it first.

Inside macros, you have access to three special variables:

varargs

If more positional arguments are passed to the macro than accepted by the macro, they end up in the special varargs variable as a list of values.
kwargs

Like varargs but for keyword arguments. All unconsumed keyword arguments are stored in this special variable.
caller

If the macro was called from a call tag, the caller is stored in this variable as a callable macro.

Macros also expose some of their internal details. The following attributes are available on a macro object:

name

The name of the macro. {{ input.name }} will print input.
arguments

A tuple of the names of arguments the macro accepts.
catch_kwargs

This is true if the macro accepts extra keyword arguments (i.e.: accesses the special kwargs variable).
catch_varargs

This is true if the macro accepts extra positional arguments (i.e.: accesses the special varargs variable).
caller

This is true if the macro accesses the special caller variable and may be called from a call tag.

If a macro name starts with an underscore, it’s not exported and can’t be imported.

Due to how scopes work in Jinja, a macro in a child template does not override a macro in a parent template. The following will output “LAYOUT”, not “CHILD”.

https://jinja.palletsprojects.com/en/stable/templates/

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Macros for Jinja or Jinja222.07.25

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