CODEWITHSUNDEEP
djangodjango-queryset
user1496093
user1496093

Reputation: 189

Django queryset grouping

Say I have these pseudo models

class Client(models.Model
    name = ...

class Property(models.Model):
    client = models.ForeignKey(Client ...)
    name = ...
    type = ...
    value = ...

For example, I have 2 clients. Each have 2 Property records. It is possible for 2 clients to own the same property, but have unique property records as each client may own a different portion of the property (value).

How can I produce a results such that it returns something like:

propertyA, {clientA, value}, {clientB, value}

propertyB, {clientA, value}

where the property is grouped on the name and type of the property?

Many thanks

iodb are you suggesting something like this?

class Client(models.Model
    name = ...

class Property(models.Model):
    name = ...
    type = ...

class PropertyValue(models.Model):
    client = models.ForeignKey(Client ...)
    property = models.ForeignKey(Property ...)
    value = models.IntegerField(...)

Upvotes: 1

Views: 52

Answers (1)

Daniel Roseman
Daniel Roseman

Reputation: 600059

Your models don't seem appropriate for the data you want to store and the result you want to get. You need to split property and value, so that there is a many-to-many relationship between Property and Client with PropertyValue as the intermediate class.

class Client(models.Model):
    name = ...
    properties = models.ManyToManyField('Property', through='PropertyValue')

class PropertyValue(models.Model):
    client = models.ForeignKey('Client' ...)
    property = models.ForeignKey('Property'...)
    value = ...

class Property(models.Model):
    name = ...
    type = ...

Now you can iterate over Properties and for each one output the value for each client:

{% for property in properties %}
    {{ property.name }}
    {% for value in property.propertyvalue_set.all %}
        {{ value.client.name }}
        {{ value.value }}
    {% endfor %}
{% endfor %}

Upvotes: 3

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