Using related_name in Django - django

Question

I am getting confused with the usage of related_name in django models, i know that the idea is to give me access to all the fields of a different table with foreignkey i am just not sure how to use it.
My model.py:
class Component(MPTTModel):
name = models.CharField(max_length=100)
manufacturer = models.CharField(max_length=100)
model = models.CharField(max_length=100)
serial_number = models.CharField(max_length=255)
price = models.IntegerField()
note = models.TextField()
image = models.ImageField(blank=True, null=True,
upload_to='components_imgs')
parent = TreeForeignKey("self", verbose_name=(
"Parent Component"), blank=True, null=True, related_name='children', on_delete=models.CASCADE)
def __str__(self):
return f"{self.id}, {self.name}"
class Job(models.Model):
job_type = (
('I', 'Interval'),
('O', 'One time'),
)
name = models.CharField(max_length=100)
description = models.CharField(max_length=100)
type = models.CharField(max_length=1, choices=job_type)
interval = models.IntegerField()
is_critical = models.BooleanField()
due_date = models.DateField()
component = models.ForeignKey(
Component, related_name='jobs', on_delete=models.CASCADE)
runninghours = models.ForeignKey(
RunningHours, related_name="RHjobs", on_delete=models.CASCADE)
def __str__(self):
return self.name
my view.py:
def worklist(request):
components = Component.objects.all()
Component_jobs = components.jobs.all()
context = {"component":components,
"Component_jobs":Component_jobs}
return render(request,"worklist.html",context)
I am trying to understand why these lines give me an error 'TreeQuerySet' object has no attribute 'jobs'
components = Component.objects.all()
Component_jobs = components.jobs.all()
but these lines work just fine,
component = Component.objects.all()
component_id = Component.objects.get(id=pk)
job_id = component_id.jobs.all()
are they not the same but with one i am getting all the jobs for a specific ID and the other i am getting all the jobs for all components?
Edited,
My template :
<div class="worklist">
{%for component in component %}
<p> {{component.name}} </p>
<div class="runninghours-table-flex">
<table class="runninghours-table">
<thead>
<tr>
<th>Job name</th>
<th>Job type</th>
<th>Due Date </th>
<th>Interval</th>
<th>Rank</th>
<th>Execute Job</th>
</tr>
</thead>
<tbody>
{% for c_jobs in component_jobs%}
<tr>
<td>{{c_jobs.name}} </td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
{%endfor%}
</tbody>
</table>
</div>
{%endfor%}
</div>

Answer 1

Assuming you want to display all components in a loop and then display all related jobs for each component in a nested loop, your template should look something like this simplified example
{% for component in components %}
{{ component }}
{% for job in component.jobs.all %}
{{ job }}
{% endfor %}
{% endfor %}
You should then use prefetch_related to fetch all related jobs for all components in a single query. There is no need to query the jobs in your view
components = Component.objects.all().prefetch_related('jobs')

Answer 2

As the error describes, this code returns a TreeQuerySet object.
components = Component.objects.all()
Trying to call fields like price will result in the same error.
components = Component.objects.all()
Component_jobs = components.price.all()
The reason this code works is because it is called on a specific Component instead of a collection of Components.
component = Component.objects.all()
component_id = Component.objects.get(id=pk)
job_id = component_id.jobs.all()
To get all jobs on a queryset, try using something like .values('jobs') from the queryset api reference
all_jobs = Component.objects.all().values('jobs')