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#5667

Python

Django template tag for dynamic attribute lookups

import re
from django import template
from django.conf import settings

numeric_test = re.compile("^\d+$")
register = template.Library()

def getattribute(value, arg):
	"""Gets an attribute of an object dynamically from a string name"""
	
	if hasattr(value, str(arg)):
		return getattr(value, arg)
	elif hasattr(value, 'has_key') and value.has_key(arg):
		return value[arg]
	elif numeric_test.match(str(arg)) and len(value) > int(arg):
		return value[int(arg)]
	else:
		return settings.TEMPLATE_STRING_IF_INVALID

register.filter('getattribute', getattribute)

# Then, in template:
# {% load getattribute %}
# {{ object|getattribute:dynamic_string_var }}
https://snipt.net/embed/117cb0eac408d2ae734873a37d10d87b/
https://snipt.net/raw/117cb0eac408d2ae734873a37d10d87b/
117cb0eac408d2ae734873a37d10d87b
python
Python
24
2014-04-24T04:24:14
True
False
/api/public/snipt/5667/
django-template-tag-for-dynamic-attribute-lookups
<table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><a href="#L-1"> 1</a> <a href="#L-2"> 2</a> <a href="#L-3"> 3</a> <a href="#L-4"> 4</a> <a href="#L-5"> 5</a> <a href="#L-6"> 6</a> <a href="#L-7"> 7</a> <a href="#L-8"> 8</a> <a href="#L-9"> 9</a> <a href="#L-10">10</a> <a href="#L-11">11</a> <a href="#L-12">12</a> <a href="#L-13">13</a> <a href="#L-14">14</a> <a href="#L-15">15</a> <a href="#L-16">16</a> <a href="#L-17">17</a> <a href="#L-18">18</a> <a href="#L-19">19</a> <a href="#L-20">20</a> <a href="#L-21">21</a> <a href="#L-22">22</a> <a href="#L-23">23</a> <a href="#L-24">24</a></pre></div></td><td class="code"><div class="highlight"><pre><span id="L-1"><a name="L-1"></a><span class="kn">import</span> <span class="nn">re</span> </span><span id="L-2"><a name="L-2"></a><span class="kn">from</span> <span class="nn">django</span> <span class="kn">import</span> <span class="n">template</span> </span><span id="L-3"><a name="L-3"></a><span class="kn">from</span> <span class="nn">django.conf</span> <span class="kn">import</span> <span class="n">settings</span> </span><span id="L-4"><a name="L-4"></a> </span><span id="L-5"><a name="L-5"></a><span class="n">numeric_test</span> <span class="o">=</span> <span class="n">re</span><span class="o">.</span><span class="n">compile</span><span class="p">(</span><span class="s">&quot;^\d+$&quot;</span><span class="p">)</span> </span><span id="L-6"><a name="L-6"></a><span class="n">register</span> <span class="o">=</span> <span class="n">template</span><span class="o">.</span><span class="n">Library</span><span class="p">()</span> </span><span id="L-7"><a name="L-7"></a> </span><span id="L-8"><a name="L-8"></a><span class="k">def</span> <span class="nf">getattribute</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> </span><span id="L-9"><a name="L-9"></a> <span class="sd">&quot;&quot;&quot;Gets an attribute of an object dynamically from a string name&quot;&quot;&quot;</span> </span><span id="L-10"><a name="L-10"></a> </span><span id="L-11"><a name="L-11"></a> <span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="nb">str</span><span class="p">(</span><span class="n">arg</span><span class="p">)):</span> </span><span id="L-12"><a name="L-12"></a> <span class="k">return</span> <span class="nb">getattr</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">arg</span><span class="p">)</span> </span><span id="L-13"><a name="L-13"></a> <span class="k">elif</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="s">&#39;has_key&#39;</span><span class="p">)</span> <span class="ow">and</span> <span class="n">value</span><span class="o">.</span><span class="n">has_key</span><span class="p">(</span><span class="n">arg</span><span class="p">):</span> </span><span id="L-14"><a name="L-14"></a> <span class="k">return</span> <span class="n">value</span><span class="p">[</span><span class="n">arg</span><span class="p">]</span> </span><span id="L-15"><a name="L-15"></a> <span class="k">elif</span> <span class="n">numeric_test</span><span class="o">.</span><span class="n">match</span><span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span> <span class="ow">and</span> <span class="nb">len</span><span class="p">(</span><span class="n">value</span><span class="p">)</span> <span class="o">&gt;</span> <span class="nb">int</span><span class="p">(</span><span class="n">arg</span><span class="p">):</span> </span><span id="L-16"><a name="L-16"></a> <span class="k">return</span> <span class="n">value</span><span class="p">[</span><span class="nb">int</span><span class="p">(</span><span class="n">arg</span><span class="p">)]</span> </span><span id="L-17"><a name="L-17"></a> <span class="k">else</span><span class="p">:</span> </span><span id="L-18"><a name="L-18"></a> <span class="k">return</span> <span class="n">settings</span><span class="o">.</span><span class="n">TEMPLATE_STRING_IF_INVALID</span> </span><span id="L-19"><a name="L-19"></a> </span><span id="L-20"><a name="L-20"></a><span class="n">register</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="s">&#39;getattribute&#39;</span><span class="p">,</span> <span class="n">getattribute</span><span class="p">)</span> </span><span id="L-21"><a name="L-21"></a> </span><span id="L-22"><a name="L-22"></a><span class="c"># Then, in template:</span> </span><span id="L-23"><a name="L-23"></a><span class="c"># {% load getattribute %}</span> </span><span id="L-24"><a name="L-24"></a><span class="c"># {{ object|getattribute:dynamic_string_var }}</span> </span></pre></div> </td></tr></table>
"template tag", django