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  <div class="section" id="switching-from-other-template-engines">
<h1>Switching from other Template Engines<a class="headerlink" href="#switching-from-other-template-engines" title="Permalink to this headline">¶</a></h1>
<p>If you have used a different template engine in the past and want to switch
to Jinja2 here is a small guide that shows the basic syntactic and semantic
changes between some common, similar text template engines for Python.</p>
<div class="section" id="jinja1">
<h2>Jinja1<a class="headerlink" href="#jinja1" title="Permalink to this headline">¶</a></h2>
<p>Jinja2 is mostly compatible with Jinja1 in terms of API usage and template
syntax.  The differences between Jinja1 and 2 are explained in the following
list.</p>
<div class="section" id="api">
<h3>API<a class="headerlink" href="#api" title="Permalink to this headline">¶</a></h3>
<dl class="docutils">
<dt>Loaders</dt>
<dd>Jinja2 uses a different loader API.  Because the internal representation
of templates changed there is no longer support for external caching
systems such as memcached.  The memory consumed by templates is comparable
with regular Python modules now and external caching doesn’t give any
advantage.  If you have used a custom loader in the past have a look at
the new <a class="reference internal" href="api.html#loaders"><span class="std std-ref">loader API</span></a>.</dd>
<dt>Loading templates from strings</dt>
<dd>In the past it was possible to generate templates from a string with the
default environment configuration by using <cite>jinja.from_string</cite>.  Jinja2
provides a <code class="xref py py-class docutils literal notranslate"><span class="pre">Template</span></code> class that can be used to do the same, but
with optional additional configuration.</dd>
<dt>Automatic unicode conversion</dt>
<dd>Jinja1 performed automatic conversion of bytestrings in a given encoding
into unicode objects.  This conversion is no longer implemented as it
was inconsistent as most libraries are using the regular Python ASCII
bytestring to Unicode conversion.  An application powered by Jinja2
<em>has to</em> use unicode internally everywhere or make sure that Jinja2 only
gets unicode strings passed.</dd>
<dt>i18n</dt>
<dd>Jinja1 used custom translators for internationalization.  i18n is now
available as Jinja2 extension and uses a simpler, more gettext friendly
interface and has support for babel.  For more details see
<a class="reference internal" href="extensions.html#i18n-extension"><span class="std std-ref">i18n Extension</span></a>.</dd>
<dt>Internal methods</dt>
<dd>Jinja1 exposed a few internal methods on the environment object such
as <cite>call_function</cite>, <cite>get_attribute</cite> and others.  While they were marked
as being an internal method it was possible to override them.  Jinja2
doesn’t have equivalent methods.</dd>
<dt>Sandbox</dt>
<dd>Jinja1 was running sandbox mode by default.  Few applications actually
used that feature so it became optional in Jinja2.  For more details
about the sandboxed execution see <code class="xref py py-class docutils literal notranslate"><span class="pre">SandboxedEnvironment</span></code>.</dd>
<dt>Context</dt>
<dd>Jinja1 had a stacked context as storage for variables passed to the
environment.  In Jinja2 a similar object exists but it doesn’t allow
modifications nor is it a singleton.  As inheritance is dynamic now
multiple context objects may exist during template evaluation.</dd>
<dt>Filters and Tests</dt>
<dd>Filters and tests are regular functions now.  It’s no longer necessary
and allowed to use factory functions.</dd>
</dl>
</div>
<div class="section" id="templates">
<h3>Templates<a class="headerlink" href="#templates" title="Permalink to this headline">¶</a></h3>
<p>Jinja2 has mostly the same syntax as Jinja1.  What’s different is that
macros require parentheses around the argument list now.</p>
<p>Additionally Jinja2 allows dynamic inheritance now and dynamic includes.
The old helper function <cite>rendertemplate</cite> is gone now, <cite>include</cite> can be used
instead.  Includes no longer import macros and variable assignments, for
that the new <cite>import</cite> tag is used.  This concept is explained in the
<a class="reference internal" href="templates.html#import"><span class="std std-ref">Import</span></a> documentation.</p>
<p>Another small change happened in the <cite>for</cite>-tag.  The special loop variable
doesn’t have a <cite>parent</cite> attribute, instead you have to alias the loop
yourself.  See <a class="reference internal" href="tricks.html#accessing-the-parent-loop"><span class="std std-ref">Accessing the parent Loop</span></a> for more details.</p>
</div>
</div>
<div class="section" id="django">
<h2>Django<a class="headerlink" href="#django" title="Permalink to this headline">¶</a></h2>
<p>If you have previously worked with Django templates, you should find
Jinja2 very familiar.  In fact, most of the syntax elements look and
work the same.</p>
<p>However, Jinja2 provides some more syntax elements covered in the
documentation and some work a bit different.</p>
<p>This section covers the template changes.  As the API is fundamentally
different we won’t cover it here.</p>
<div class="section" id="method-calls">
<h3>Method Calls<a class="headerlink" href="#method-calls" title="Permalink to this headline">¶</a></h3>
<p>In Django method calls work implicitly, while Jinja requires the explicit
Python syntax. Thus this Django code:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">for</span> <span class="nv">page</span> <span class="k">in</span> <span class="nv">user.get_created_pages</span> <span class="cp">%}</span>
    ...
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>…looks like this in Jinja:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">for</span> <span class="nv">page</span> <span class="k">in</span> <span class="nv">user.get_created_pages</span><span class="o">()</span> <span class="cp">%}</span>
    ...
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>This allows you to pass variables to the method, which is not possible in
Django. This syntax is also used for macros.</p>
</div>
<div class="section" id="filter-arguments">
<h3>Filter Arguments<a class="headerlink" href="#filter-arguments" title="Permalink to this headline">¶</a></h3>
<p>Jinja2 provides more than one argument for filters.  Also the syntax for
argument passing is different.  A template that looks like this in Django:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{{</span> <span class="nv">items</span><span class="o">|</span><span class="nf">join</span><span class="s2">:&quot;, &quot;</span> <span class="cp">}}</span>
</pre></div>
</div>
<p>looks like this in Jinja2:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{{</span> <span class="nv">items</span><span class="o">|</span><span class="nf">join</span><span class="o">(</span><span class="s1">&#39;, &#39;</span><span class="o">)</span> <span class="cp">}}</span>
</pre></div>
</div>
<p>It is a bit more verbose, but it allows different types of arguments -
including variables - and more than one of them.</p>
</div>
<div class="section" id="tests">
<h3>Tests<a class="headerlink" href="#tests" title="Permalink to this headline">¶</a></h3>
<p>In addition to filters there also are tests you can perform using the is
operator.  Here are some examples:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">if</span> <span class="nv">user.user_id</span> <span class="k">is</span> <span class="nf">odd</span> <span class="cp">%}</span>
    <span class="cp">{{</span> <span class="nv">user.username</span><span class="o">|</span><span class="nf">e</span> <span class="cp">}}</span> is odd
<span class="cp">{%</span> <span class="k">else</span> <span class="cp">%}</span>
    hmm. <span class="cp">{{</span> <span class="nv">user.username</span><span class="o">|</span><span class="nf">e</span> <span class="cp">}}</span> looks pretty normal
<span class="cp">{%</span> <span class="k">endif</span> <span class="cp">%}</span>
</pre></div>
</div>
</div>
<div class="section" id="loops">
<h3>Loops<a class="headerlink" href="#loops" title="Permalink to this headline">¶</a></h3>
<p>For loops work very similarly to Django, but notably the Jinja2 special
variable for the loop context is called <cite>loop</cite>, not <cite>forloop</cite> as in Django.</p>
<p>In addition, the Django <cite>empty</cite> argument is called <cite>else</cite> in Jinja2. For
example, the Django template:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">for</span> <span class="nv">item</span> <span class="k">in</span> <span class="nv">items</span> <span class="cp">%}</span>
    <span class="cp">{{</span> <span class="nv">item</span> <span class="cp">}}</span>
<span class="cp">{%</span> <span class="k">empty</span> <span class="cp">%}</span>
    No items!
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>…looks like this in Jinja2:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">for</span> <span class="nv">item</span> <span class="k">in</span> <span class="nv">items</span> <span class="cp">%}</span>
    <span class="cp">{{</span> <span class="nv">item</span> <span class="cp">}}</span>
<span class="cp">{%</span> <span class="k">else</span> <span class="cp">%}</span>
    No items!
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
</div>
<div class="section" id="cycle">
<h3>Cycle<a class="headerlink" href="#cycle" title="Permalink to this headline">¶</a></h3>
<p>The <code class="docutils literal notranslate"><span class="pre">{%</span> <span class="pre">cycle</span> <span class="pre">%}</span></code> tag does not exist in Jinja2; however, you can achieve the
same output by using the <cite>cycle</cite> method on the loop context special variable.</p>
<p>The following Django template:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">for</span> <span class="nv">user</span> <span class="k">in</span> <span class="nv">users</span> <span class="cp">%}</span>
    <span class="p">&lt;</span><span class="nt">li</span> <span class="na">class</span><span class="o">=</span><span class="s">&quot;</span><span class="cp">{%</span> <span class="k">cycle</span> <span class="s1">&#39;odd&#39;</span> <span class="s1">&#39;even&#39;</span> <span class="cp">%}</span><span class="s">&quot;</span><span class="p">&gt;</span><span class="cp">{{</span> <span class="nv">user</span> <span class="cp">}}</span><span class="p">&lt;/</span><span class="nt">li</span><span class="p">&gt;</span>
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>…looks like this in Jinja2:</p>
<div class="highlight-html+jinja notranslate"><div class="highlight"><pre><span></span><span class="cp">{%</span> <span class="k">for</span> <span class="nv">user</span> <span class="k">in</span> <span class="nv">users</span> <span class="cp">%}</span>
    <span class="p">&lt;</span><span class="nt">li</span> <span class="na">class</span><span class="o">=</span><span class="s">&quot;</span><span class="cp">{{</span> <span class="nb">loop</span><span class="nv">.cycle</span><span class="o">(</span><span class="s1">&#39;odd&#39;</span><span class="o">,</span> <span class="s1">&#39;even&#39;</span><span class="o">)</span> <span class="cp">}}</span><span class="s">&quot;</span><span class="p">&gt;</span><span class="cp">{{</span> <span class="nv">user</span> <span class="cp">}}</span><span class="p">&lt;/</span><span class="nt">li</span><span class="p">&gt;</span>
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>There is no equivalent of <code class="docutils literal notranslate"><span class="pre">{%</span> <span class="pre">cycle</span> <span class="pre">...</span> <span class="pre">as</span> <span class="pre">variable</span> <span class="pre">%}</span></code>.</p>
</div>
</div>
<div class="section" id="mako">
<h2>Mako<a class="headerlink" href="#mako" title="Permalink to this headline">¶</a></h2>
<p>If you have used Mako so far and want to switch to Jinja2 you can configure
Jinja2 to look more like Mako:</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">env</span> <span class="o">=</span> <span class="n">Environment</span><span class="p">(</span><span class="s1">&#39;&lt;%&#39;</span><span class="p">,</span> <span class="s1">&#39;%&gt;&#39;</span><span class="p">,</span> <span class="s1">&#39;${&#39;</span><span class="p">,</span> <span class="s1">&#39;}&#39;</span><span class="p">,</span> <span class="s1">&#39;&lt;</span><span class="si">%d</span><span class="s1">oc&gt;&#39;</span><span class="p">,</span> <span class="s1">&#39;&lt;/</span><span class="si">%d</span><span class="s1">oc&gt;&#39;</span><span class="p">,</span> <span class="s1">&#39;%&#39;</span><span class="p">,</span> <span class="s1">&#39;##&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>With an environment configured like that, Jinja2 should be able to interpret
a small subset of Mako templates.  Jinja2 does not support embedded Python
code, so you would have to move that out of the template.  The syntax for defs
(which are called macros in Jinja2) and template inheritance is different too.
The following Mako template:</p>
<div class="highlight-html+mako notranslate"><div class="highlight"><pre><span></span><span class="cp">&lt;%</span><span class="nb">inherit</span> <span class="na">file=</span><span class="s">&quot;layout.html&quot;</span> <span class="cp">/&gt;</span>
<span class="cp">&lt;%</span><span class="nb">def</span> <span class="na">name=</span><span class="s">&quot;title()&quot;</span><span class="cp">&gt;</span>Page Title<span class="cp">&lt;/%</span><span class="nb">def</span><span class="cp">&gt;</span>
<span class="p">&lt;</span><span class="nt">ul</span><span class="p">&gt;</span>
<span class="cp">%</span> <span class="k">for</span> <span class="n">item</span> <span class="ow">in</span> <span class="nb">list</span><span class="p">:</span>
    <span class="p">&lt;</span><span class="nt">li</span><span class="p">&gt;</span><span class="cp">${</span><span class="n">item</span><span class="cp">}</span><span class="p">&lt;/</span><span class="nt">li</span><span class="p">&gt;</span>
<span class="cp">%</span><span class="k"> endfor</span>
<span class="p">&lt;/</span><span class="nt">ul</span><span class="p">&gt;</span>
</pre></div>
</div>
<p>Looks like this in Jinja2 with the above configuration:</p>
<div class="highlight-html+mako notranslate"><div class="highlight"><pre><span></span><span class="cp">&lt;%</span> <span class="n">extends</span> <span class="s2">&quot;layout.html&quot;</span> <span class="cp">%&gt;</span>
<span class="cp">&lt;%</span> <span class="n">block</span> <span class="n">title</span> <span class="cp">%&gt;</span>Page Title<span class="cp">&lt;%</span> <span class="n">endblock</span> <span class="cp">%&gt;</span>
<span class="cp">&lt;%</span> <span class="n">block</span> <span class="n">body</span> <span class="cp">%&gt;</span>
<span class="p">&lt;</span><span class="nt">ul</span><span class="p">&gt;</span>
<span class="cp">%</span> <span class="k">for</span> <span class="n">item</span> <span class="ow">in</span> <span class="nb">list</span><span class="p">:</span>
    <span class="p">&lt;</span><span class="nt">li</span><span class="p">&gt;</span><span class="cp">${</span><span class="n">item</span><span class="cp">}</span><span class="p">&lt;/</span><span class="nt">li</span><span class="p">&gt;</span>
<span class="cp">%</span><span class="k"> endfor</span>
<span class="p">&lt;/</span><span class="nt">ul</span><span class="p">&gt;</span>
<span class="cp">&lt;%</span> <span class="n">endblock</span> <span class="cp">%&gt;</span>
</pre></div>
</div>
</div>
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  <h3><a href="index.html">Table Of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#">Switching from other Template Engines</a><ul>
<li><a class="reference internal" href="#jinja1">Jinja1</a><ul>
<li><a class="reference internal" href="#api">API</a></li>
<li><a class="reference internal" href="#templates">Templates</a></li>
</ul>
</li>
<li><a class="reference internal" href="#django">Django</a><ul>
<li><a class="reference internal" href="#method-calls">Method Calls</a></li>
<li><a class="reference internal" href="#filter-arguments">Filter Arguments</a></li>
<li><a class="reference internal" href="#tests">Tests</a></li>
<li><a class="reference internal" href="#loops">Loops</a></li>
<li><a class="reference internal" href="#cycle">Cycle</a></li>
</ul>
</li>
<li><a class="reference internal" href="#mako">Mako</a></li>
</ul>
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