Having trouble writing loops in django template

Question

Hello guys I am currently working on django views and templates and met some problems. I have a model named 'metabolites', which contains: id, name, compartment, charge and formula 5 components. I have another model named 'Reactionsmeta', which contains: id(reactions), name, metabolie1, metabolite2, .... metabolite6. The table of this model is not filled complete, because sometimes one id corresponds to 5 metabolites, but sometimes even 20.

I write a template which can displays all the reaction, when I click on the reaction and enter the detail page, I also want to display the metabolites that involve in this reactions. My views.py and templates are written as below:

reactions_detail.html

{% extends 'Recon/Base.html' %}
{% load static %}
{% block title %}Reaction Details{% endblock %}
{% block body %}
<h1>{{ reactionsmeta.id }}</h1>
<h2>{{ reactionsmeta.name}}</h2>
<!-- Left Album Info -->
<div class="col-sm-4 col-md-3">
    <div class="panel panel-default">
        <div class="panel-body">
            <a href="{% url 'detail_reaction' reactionsmeta.id %}">
                {% if reactionsmeta.id %}
                    <img src="{% static "Recon/images/Logo-Technische-Universiteit-Eindhoven.jpg" %}" class="img-responsive">
                {% else %}
                    <h3>No image to display</h3>
                {% endif %}
            </a>
            <h1>{{ reactionsmeta.id }} <small>{{ reactionsmeta.name }}</small></h1>
        </div>
    </div>
</div>

views.py
from django.views import generic
from .models import Reactionsmeta,Metabolites,Reactions
from django.shortcuts import render


class IndexView(generic.ListView):
template_name = 'Recon/index.html'
context_object_name = 'Reactions_object'

def get_queryset(self):
    return Reactionsmeta.objects.all()


class DetailsView(generic.DetailView):
model = Reactionsmeta
template_name = 'Recon/reactions_detail.html'

def get_context_data(self, **kwargs):
    context = super(DetailsView, self).get_context_data(**kwargs)
    context['metabolite'] = Metabolites.objects.all()
    context['reactions'] = Reactions.objects.all()

    # And so on for more models
    return context

How can I write the loop in reaction_detail.html???

EDIT:

class Metabolites(models.Model):
id = models.CharField(primary_key=True, max_length=255)
name = models.CharField(max_length=255, blank=True, null=True)
compartment = models.CharField(max_length=255, blank=True, null=True)
charge = models.CharField(max_length=255, blank=True, null=True)
formula = models.CharField(max_length=255, blank=True, null=True)
notes = models.CharField(max_length=255, blank=True, null=True)

class Meta:
    managed = False
    db_table = 'Metabolites'

class Reactionsmeta(models.Model):
id = models.CharField(primary_key=True, max_length=255)
name = models.CharField(max_length=255, blank=True, null=True)
metabolite1 = models.ForeignKey('Metabolites', db_column='metabolite1', 
blank=True, null=True, on_delete=models.CASCADE)
stoichiometry1 = models.IntegerField(blank=True, null=True)
metabolite2 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry2 = models.IntegerField(blank=True, null=True)
metabolite3 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry3 = models.CharField(max_length=255, blank=True, null=True)
......
stoichiometry55 = models.CharField(max_length=255, blank=True, null=True)
metabolite56 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry56 = models.CharField(max_length=255, blank=True, null=True)
metabolite57 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry57 = models.CharField(max_length=255, blank=True, null=True)
metabolite58 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry58 = models.CharField(max_length=255, blank=True, null=True)
metabolite59 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry59 = models.CharField(max_length=255, blank=True, null=True)
metabolite60 = models.CharField(max_length=255, blank=True, null=True)
stoichiometry60 = models.CharField(max_length=255, blank=True, null=True)

class Meta:
    managed = False
    db_table = 'ReactionsMeta'

Answer 1

I don't see a great way to do this since each metabolite has its own field and isn't necessarily a foreign key. It'd be easier if the metabolite were in a ManyToMany field with through defining the stoichiometry.

Django's ManyToMany Relationship with Additional Fields

https://docs.djangoproject.com/en/2.0/topics/db/examples/many_to_many/

That said, in the template you can display a Reactionsmeta metabolite1 and stoichiometry one by :

{% if reactionsmeta.metabolite1 %}
    Metabolite: {% reactionsmeta.metabolite1 %}
    Stoichiometry: {% reactionsmeta.stoichiometry1 %}
{% endif %}
{% if reactionsmeta.metabolite2 %}
    Metabolite: {% reactionsmeta.metabolite2 %}
    Stoichiometry: {% reactionsmeta.stoichiometry2 %}
{% endif %}
...
{% if reactionsmeta.metabolite60 %}
    Metabolite: {% reactionsmeta.metabolite60 %}
    Stoichiometry: {% reactionsmeta.stoichiometry60 %}
{% endif %}

Problems with the above:

1. It's terrably repetative
2. If the fields are in fact Foreign Keys their raw values wont't mean anything to the user.

EDIT: Response to comment that CharFields are in fact FKs.

So I think you need to query db for the information about the metabolites in the view and return that to the template. I think, by design, templates are not supposed to be able to access the db.

EDIT: I'm afraid you're going to have to learn how to write custom views. It's really not bad but it's hard to do some of the things you're attempting just using the generics.

https://docs.djangoproject.com/en/2.0/topics/http/views/