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Python

Posted by csj
csj
12,678 Points

[Django] Explain to me like I'm five - reserve lookup that span relationships

Can someone please explain to me like I'm five how and what is going when you want to making a reserve lookup that span relationships? Or recommend a certain video(s). I'm completely stuck in relationships and how pull data out of database.

I've been reading trough https://docs.djangoproject.com/en/1.10/topics/db/queries/#lookups-that-span-relationships and ListView documentation. But I can't adapt what I read to my own needs. So I conclude that I don't understand what I'm reading.

I need to learn how to get a hold project.title and project.featured_image of App 1's Project model inside App 2's template HTML. And I've set App 2's model the a ForeignKey to Project. But that isn't enough, so either something isn't right with the map/views.py or I'm not drilling down correctly inside the map_list.html.

I've just left "title": "{{ project.title }}", for reference. I've tried a bunch of things, all kind of variations of for loops. In the style of for mapdata in project.map.all and mapdata.title etc.

Here is the setup:

App 1: projects

projects/models.py

from django.db import models


class Project(models.Model):
    title = models.CharField(max_length=200)
    text = models.TextField()
    date = models.DateField()
    featured_image = models.ImageField(
        upload_to='projects/featured', blank=True)

projects/views.py

from django.shortcuts import render
from django.views.generic import ListView, DetailView

from .models import Project
from .models import ProjectImage


class ProjectListView(ListView):
    model = Project


class ProjectDetailView(DetailView):
    model = Project

projects/template/projects/project_list.html (every get outputted as expected)

{% for project in object_list %}
<div class="card {{ project.title }} {{ project.get_typology_display }}">
  <div class="featured_image">
    <img src="{{ MEDIA_URL }}/media/{{ project.featured_image }}" alt="{{ project.title }}" />
  </div>
  <h4><a href="{% url 'projects:project-detail' project.pk %}">{{ project.title }}</a></h4>
  <h5>{{ project.get_typology_display }}</h5>
</div>
{% endfor %}

App 2: map

map/models.py

from django.db import models

from projects.models import Project

class Map(models.Model):
    project = models.ForeignKey(Project, related_name='map')
    lon = models.DecimalField(max_digits=10, decimal_places=8, default=1)
    lat = models.DecimalField(max_digits=10, decimal_places=8, default=1)
    location = models.CharField(max_length=200, blank=True)

map/views.py

from django.shortcuts import render
from django.views.generic import ListView, DetailView

from .models import Map
from projects.models import Project


class MapListView(ListView):
    model = Map

Snippet from map/template/map/map_list.html (map.lon and map.lat works)

var markers = {
  type: 'FeatureCollection',
  features: [
    {% for map in object_list %}
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          {{ map.lon }},
          {{ map.lat }}
        ]
      },
      "properties": {
        "title": "{{ project.title }}",
        "marker-symbol": "marker"
      }
    },
    {% endfor %}
  ]
};

I know this is perhaps convoluted. Sorry.

2 Answers

jacinator
jacinator
11,936 Points

project would now be an attribute of Map, so to access it in the context data you should refer to it by {{ map.project.title }}. I've modified the code below. Give that a try and good luck!

var markers = {
  type: 'FeatureCollection',
  features: [
    {% for map in object_list %}
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          {{ map.lon }},
          {{ map.lat }}
        ]
      },
      "properties": {
        "title": "{{ map.project.title }}",  // Try changing this line like so
        "marker-symbol": "marker"
      }
    },
    {% endfor %}
  ]
};
csj
csj
12,678 Points
csj
csj
12,678 Points

You're turning out to be my savior... Although I'm embarrassed, I'm sure I try the line out... Or I didn't :)... Perhaps it was inside an invalid loop I tried it. I get so confused sometimes, I can't remember what and how. Trying something new from the docs, I can completely loss my head.

jacinator
jacinator
11,936 Points

Been there, done that. :)