MySQL - Django comment sélectionner valeur étrangère dans requête - Stack Overflow

Having following models:

User(models.Model):
    ...
    login = ...

Asset(models.Model):
    user = models.ForeignKey(User)
    ...

How to select users login in Asset query using django QuerySet capabilities. For example:

Asset.objects.extra(select = {'user_login' : 'user__login'})

make to return query set with user_login field in each model object

Each Asset object already has a foreign key to the user. So you can always access -

asset = Asset.objects.get(pk=any_id)
if asset.user.login == 'some_value':
    do_some_magic()

Please read the documentation.

Use .select_related('user') to select all assets and related users in a single query. Then simply access it through asset.user.login.

assets = Asset.objects.selec_related('user').filter(<any filter>)

for asset in assets:
    # no additional queries here, as the user objects are preloaded into memory
    print asset.user.login

I have found following solution:

Asset.object.extra( select = {'user_login' : '`%s.%s`' % (User._meta.db_table, 'login') } ).order_by('user__login')

The order_by expression is used to make JOIN on User's model table, than user's login can be accessed in SELECT expression within user_table.login

Having following models:

User(models.Model):
    ...
    login = ...

Asset(models.Model):
    user = models.ForeignKey(User)
    ...

How to select users login in Asset query using django QuerySet capabilities. For example:

Asset.objects.extra(select = {'user_login' : 'user__login'})

make to return query set with user_login field in each model object

Each Asset object already has a foreign key to the user. So you can always access -

asset = Asset.objects.get(pk=any_id)
if asset.user.login == 'some_value':
    do_some_magic()

Please read the documentation.

Use .select_related('user') to select all assets and related users in a single query. Then simply access it through asset.user.login.

assets = Asset.objects.selec_related('user').filter(<any filter>)

for asset in assets:
    # no additional queries here, as the user objects are preloaded into memory
    print asset.user.login

I have found following solution:

Asset.object.extra( select = {'user_login' : '`%s.%s`' % (User._meta.db_table, 'login') } ).order_by('user__login')

The order_by expression is used to make JOIN on User's model table, than user's login can be accessed in SELECT expression within user_table.login

Source