Simple Templating Engine¶

Variables¶

Template variables are defined by the context dictionary passed to the template.

You can mess around with the variables in templates provided they are passed in by the application. Variables may have attributes or elements on them you can access too like done in standard Python syntax.

Examples:

• {{ foo.bar }}

• {{ foo['bar'] }}

If a variable or attribute does not exist, you will get back an error.

Variable names must comply with the same rules as naming variables in Python: * The first character of a variable name must be a letter (a-z, A-Z) or underscore (_) * The remaining characters in a variable name can be letters, numbers or underscore * Variable names are case-sensitive

Filters¶

Variables can be modified by filters. Filters are separated from the variable by a pipe symbol (|) and may have optional arguments are seperated by colon (:). Multiple filters can be chained. The output of one filter is applied to the next.

For example, {{ name|tag1|tag2 }} will first call tag1 and output is passed to tag2 and return is rendered.

Filters that accept arguments have arguments seperated by colon (:). For example: {{ listx|join:', ' }} will join a list with commas (str.join(', ', listx)).

Supported filters are:

• uppercase: Convert string to uppercase.

• lowercase: Convert string to lowercase.

• titlecase: Convert string to titlecase.

• datetime: String format datetime.

• base64: Encode string to base64.

Condition¶

To add decision-making inside templates, so conditionals are available. These are just like Python condition but enclosed in {%, %} like {% if <condition> %}. There must be {% endif %} block to close the block.

Example:

{% if user.is_logged_in %}
    <p>Welcome, {{ user.name }}!</p>
{% endif %}

if block can have optional else block.

Example:

{% if user.is_logged_in %}
    <p>Welcome, {{ user.name }}!</p>
{% else %}
    <p>Welcome, guest!</p>
{% endif %}

Loop¶

To iterate over collection of elements:

Example:

{% for product in product_list %}
    {{ product.name }}: {{ product.price|format_price }}
{% endfor %}

Comments¶

To comment-out part of a line in a template, use the comment syntax.

Example:

• {# This is comment and will be ignored #}