Question

Djnago model:

class RootTable(models.Model):
    id = models.IntegerField(primary_key=True)
    field1 = models.CharField(max_length=100, unique=True)
    field2 = models.CharField(max_length=120, unique=True)

class SubTableA(models.Model):
    id = models.IntegerField(primary_key=True)
    field1 = models.ForeignKey(RootTable, null=True, blank=True)
    subtableAfield1 = models.CharField(max_length=180, blank=True)

class SubTableB(models.Model):
    id = models.IntegerField(primary_key=True)
    field1 = models.ForeignKey(SubTableA, null=True, blank=True)
    subtableBfield1 = models.CharField(max_length=180, blank=True)

class SubTable2(models.Model):
    id = models.IntegerField(primary_key=True)
    field1 = models.ForeignKey(RootTable, null=True, blank=True)
    subtable2field1 = models.CharField(max_length=180, blank=True)
    subtable2field2 = models.CharField(max_length=180, blank=True)

If I use request like this:

RootTable.objects.filter( subtable2__subtable2field1 = 'text' )

It returns values only from ‘RootTable’.
SQL:

SELECT  'roottable'.'id',
        'roottable'.'field1',
        'roottable'.'field2',
FROM 'roottable'
INNER JOIN ...

But how can I get all connected values from other tables?
SQL:

SELECT  'roottable'.'id',
        'roottable'.'field1',
        'roottable'.'field2',
        'subtablea'.'subtableafield1',
        'subtableb'.'subtablebfield1',
        'subtable2'.'subtable2field1',
        'subtable2'.'subtable2field2',
FROM 'roottable', 'subtablea', 'subtableb', 'subtable2'
INNER JOIN ...

UPDATE:

I receive a response something like this:

[
{ 'roottable.id' : 'rid'},
{ 'subtablea.id' : 'id'},
{ 'subtablea.subtableafield1' : 'value1' },
...
{ 'roottable.id' : 'rid'},
{ 'subtablea.id' : 'id'},
{ 'subtablea.subtableafield1' : 'value2' },
]

But I need something like this:

[
{ 'roottable.id' : 'rid'},
{ 'subtablea.id' : 'id'},
{ 'subtablea.subtableafield1' : ['value1','value2'] },
]

is there a fast way to get such structure?

Answer 1

Django filter() query returns objects not the specific attributes. However, you can use values() to return just attributes dict. This can also take attributes of related field.

But the side-effect is you have to pass attribute names that you want to get back (similar to SQL).

So you can change your query as

RootTable.objects.filter(subtable2__subtable2field1='text').values('field1', 
    'field2', 'subtablea__subtable1field1', 'subtableb__subtable2field1')

More reference at Django Queryset values