[Fixed]-Use of a boolean flag inside django 1.9 (template)

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You’re trying to do too much logic in the template. You can’t assign variables as your comment ## Set a flag to 1 ## suggests.

In your view, create two querysets. One of all the activities, and one for the spectra without an activity.

activities = Activitydiagram.objects.filter(enzymes=enzyme)
spectras_without_activities = Spectraimage.objects.filter(enzymes=enzyme, activity=None)

Then, in your template, loop through the activities, and use the reverse relation to get the related spectra for each activity.

{% for activity in activities %}
    {{ activity }}
    {% for spectra in activity.spectraimage_set.all %}
        {{ spectra }}
    {% endfor %}
{% endfor %}

At the end, you can loop through your spectra which do not have a related activity.

{% for spectra in spectras_without_activities %}
    {{ spectra }}
{% endfor %}

The code above assumes that spectra.enzyme == activity.enzyme for every spectra in activity.spectraimage_set.all. If that’s not the case, you’ll have to add an additional check.

Once you’ve got it working, you optimise the query by using prefetch_related to fetch the related spectras at the same time as the activities.

👤Alasdair

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