ustache, Mustache for Python
Project description
ustache
Mustache for Python.
Documentation: ustache.readthedocs.io
Usage
import ustache
print(ustache.render('Hello {{v}}', {'v': 'World!'}))
# Hello World!
Command line:
$ ustache -j data.json -o output.html template.mustache
Highlights
- Command line interface.
- Spec compliant, but also highly compatible with
Mustache.js
. - Fast and small codebase, efficiently rendering to
str
orbytes
, supporting streaming. - Customizable (property getter, partial resolver, and stringify, escape and lambda render functions).
- Customizable template cache, with optional extreme memory-efficient mode (see xxhash optional dependency below).
Considerations
For inter-compatibility with JavaScript (especially Mustache.js
, enabling
client-side rendering with the same templates), ustache exposes some
atypical behavior:
- Mustache blocks stick to JavaScript falseness (
__bool__
is not honored):None
,False
,0
,nan
, and empty sequences (including strings) are taken as falsy, while everything else (including empty mappings) will be considered truthy (Mustache.js
Boolean
and emptyArray
handling). - Mustache blocks receiving any iterable other than mappings and strings
will result on a loop (
Mustache.js
Array
handling). - Non-mapping sized objects will expose a virtual
length
property (JavaScriptArray.length
emulation). Customizable viagetter
parameter. - Mapping keys containing dot (
.
) or whitespace (Mustache.js
property name limitation). Customizable viagetter
parameter. - Sequence elements are accessible by positive index in the same way mapping
integer-keyed items are also accessible when no string key conflicts, as
properties (JavaScript
Object
emulation). Customizable viagetter
parameter.
Optional dependencies
For minimalism and portability, ustache has no hard dependencies, while still supporting some libraries for added functionality:
- xxhash will be used, if available, to avoid storing the whole template data as part of the template cache, dramatically reducing its memory footprint on many situations.
Optional but generally recommended dependencies can be easily installed
all at once using ustache optional
extra target:
pip install ustache[optional]
Syntax
Check out the mustache(5) manual.
For quick reference, here is a quick overview of the Mustache syntax.
Template (template.mustache
):
{{!comment}}
<ul>
{{#object}}<li>{{property}}</li>{{/object}}
{{^object}}<li>As <b>object</b> is truthy, this won't be shown</li>{{/object}}
{{^null}}<li><b>null</b> is falsy</li>{{/null}}
{{#array}}<li>{{property}}</li>
{{/array}}
{{^array}}<li>Array isn't empty, this won't be shown.</li>{{/array}}
{{#empty_array}}<li>Empty Array, this won't be shown</li>{{/empty_array}}
{{^empty_array}}<li>empty_array is empty</li>{{/empty_array}}
{{&unescaped_html}}
</ul>
Data (data.json
):
{
"object": {
"property": "Object property value"
},
"null": null,
"array": [
{"property": "Array item1 property"},
{"property": "Array item2 property"},
{"property": "Array item3 property"}
],
"empty_array": [],
"unescaped_html": "<li>this is unescaped html</li>"
}
Command:
$ python -m ustache -j data.json -o template.mustache
Output:
<ul>
<li>Object property value</li>
<li><b>null</b> is falsy</li>
<li>Array item1 property</li>
<li>Array item2 property</li>
<li>Array item3 property</li>
<li>empty_array is empty</li>
<li>this is unescaped html</li>
</ul>
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