Python - Unable to modify the serializer.data dictionary in Django Rest Framework
<p>I have tried to add a key <code>serializer.data['test'] = 'asdf'</code>, this does not appear to do anything.</p>

<p>I want to transform the representation of a key's value. To do this, I'm trying to use the value to calculate a new value and replace the old one in the dictionary.</p>

<p>This is what I want to accomplish, but I don't know why the value is not being replaced. There are no errors thrown, and the resulting dictionary has no evidence that I've tried to replace anything:</p>

<pre><code>class PlaceDetail(APIView):
    def get(self, request, pk, format=None):
        place = Place.objects.select_related().get(pk=pk)
        serializer = PlaceSerializer(place)
        #serializer.data['tags'] = pivot_tags(serializer.data['tags'])
        serializer.data['test'] = 'asdf'
        print(serializer.data['test'])
        return Response(serializer.data)
</code></pre>

<p>Terminal: <code>KeyError: 'test'</code></p>

<p>I have observed by printing that <code>serializer.data</code> is a dictionary.</p>

<p>I have also tested that the syntax I'm trying to use should work:</p>

<pre><code>&gt;&gt;&gt; test = {'a': 'Alpha'}
&gt;&gt;&gt; test
{'a': 'Alpha'}
&gt;&gt;&gt; test['a']
'Alpha'
&gt;&gt;&gt; test['a'] = 'asdf'
&gt;&gt;&gt; test
{'a': 'asdf'}
</code></pre>

<p>How can I properly modify the <code>serializer.data</code> dictionary?</p>