How to create union of two different django-models?
I have two django-models
class ModelA(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_a')
other_column = models.CharField(/*...*/ db_column='other_column_a')
class ModelB(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_b')
other_column = None
Then I want to merge the two querysets of this models using union
ModelA.objects.all().union(ModelB.objects.all())
But in query I see
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`
FROM `model_b`)
Of course I got the exception The used SELECT statements have a different number of columns.
How to create the aliases and fake columns to use union-query?
mysql django django-models union
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
add a comment |
I have two django-models
class ModelA(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_a')
other_column = models.CharField(/*...*/ db_column='other_column_a')
class ModelB(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_b')
other_column = None
Then I want to merge the two querysets of this models using union
ModelA.objects.all().union(ModelB.objects.all())
But in query I see
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`
FROM `model_b`)
Of course I got the exception The used SELECT statements have a different number of columns.
How to create the aliases and fake columns to use union-query?
mysql django django-models union
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
add a comment |
I have two django-models
class ModelA(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_a')
other_column = models.CharField(/*...*/ db_column='other_column_a')
class ModelB(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_b')
other_column = None
Then I want to merge the two querysets of this models using union
ModelA.objects.all().union(ModelB.objects.all())
But in query I see
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`
FROM `model_b`)
Of course I got the exception The used SELECT statements have a different number of columns.
How to create the aliases and fake columns to use union-query?
mysql django django-models union
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
I have two django-models
class ModelA(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_a')
other_column = models.CharField(/*...*/ db_column='other_column_a')
class ModelB(models.Model):
title = models.CharField(..., db_column='title')
text_a = models.CharField(..., db_column='text_b')
other_column = None
Then I want to merge the two querysets of this models using union
ModelA.objects.all().union(ModelB.objects.all())
But in query I see
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`
FROM `model_b`)
Of course I got the exception The used SELECT statements have a different number of columns.
How to create the aliases and fake columns to use union-query?
mysql django django-models union
mysql django django-models union
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
asked Nov 27 '18 at 8:55
DmitryDmitry
197217
197217
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
In SQL query, we can use NULL to define the remaining columns/aliases
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`,
NULL
FROM `model_b`)
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
Thanks for answer. I know how useunionin mysql. I want to know how to describe it in django-models
– Dmitry
Nov 27 '18 at 9:34
@Dmitry I dont have much experience with Django. But based on some searches, you can useValue()orannotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308
– Madhur Bhaiya
Nov 27 '18 at 9:42
add a comment |
In Django, union operations needs to have same columns, so with values_list you can use those specific columns only like this:
qsa = ModelA.objects.all().values('text_a', 'title')
qsb = ModelB.objects.all().values('text_a', 'title')
qsa.union(qsb)
But there is no way(that I know of) to mimic NULL in union in Django. So there are two ways you can proceed here.
First One, add an extra field in your Model with name other_column. You can put the values empty like this:
other_column = models.CharField(max_length=255, null=True, default=None)
and use the Django queryset union operations as described in here.
Last One, the approach is bit pythonic. Try like this:
a = ModelA.objects.values_list('text_a', 'title', 'other_column')
b = ModelB.objects.values_list('text_a', 'title')
union_list = list()
for i in range(0, len(a)):
if b[i] not in a[i]:
union_list.append(b[i])
union_list.append(a[i])
Hope it helps!!
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
In SQL query, we can use NULL to define the remaining columns/aliases
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`,
NULL
FROM `model_b`)
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
Thanks for answer. I know how useunionin mysql. I want to know how to describe it in django-models
– Dmitry
Nov 27 '18 at 9:34
@Dmitry I dont have much experience with Django. But based on some searches, you can useValue()orannotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308
– Madhur Bhaiya
Nov 27 '18 at 9:42
add a comment |
In SQL query, we can use NULL to define the remaining columns/aliases
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`,
NULL
FROM `model_b`)
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
Thanks for answer. I know how useunionin mysql. I want to know how to describe it in django-models
– Dmitry
Nov 27 '18 at 9:34
@Dmitry I dont have much experience with Django. But based on some searches, you can useValue()orannotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308
– Madhur Bhaiya
Nov 27 '18 at 9:42
add a comment |
In SQL query, we can use NULL to define the remaining columns/aliases
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`,
NULL
FROM `model_b`)
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
In SQL query, we can use NULL to define the remaining columns/aliases
(SELECT
`model_a`.`title`,
`model_a`.`text_a`,
`model_a`.`other_column`
FROM `model_a`)
UNION
(SELECT
`model_b`.`title`,
`model_b`.`text_b`,
NULL
FROM `model_b`)
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
answered Nov 27 '18 at 8:56
Madhur BhaiyaMadhur Bhaiya
19.6k62236
19.6k62236
Thanks for answer. I know how useunionin mysql. I want to know how to describe it in django-models
– Dmitry
Nov 27 '18 at 9:34
@Dmitry I dont have much experience with Django. But based on some searches, you can useValue()orannotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308
– Madhur Bhaiya
Nov 27 '18 at 9:42
add a comment |
Thanks for answer. I know how useunionin mysql. I want to know how to describe it in django-models
– Dmitry
Nov 27 '18 at 9:34
@Dmitry I dont have much experience with Django. But based on some searches, you can useValue()orannotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308
– Madhur Bhaiya
Nov 27 '18 at 9:42
Thanks for answer. I know how use
union in mysql. I want to know how to describe it in django-models– Dmitry
Nov 27 '18 at 9:34
Thanks for answer. I know how use
union in mysql. I want to know how to describe it in django-models– Dmitry
Nov 27 '18 at 9:34
@Dmitry I dont have much experience with Django. But based on some searches, you can use
Value() or annotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308– Madhur Bhaiya
Nov 27 '18 at 9:42
@Dmitry I dont have much experience with Django. But based on some searches, you can use
Value() or annotate(). check this answer: stackoverflow.com/a/52858358/2469308 and stackoverflow.com/a/34755617/2469308– Madhur Bhaiya
Nov 27 '18 at 9:42
add a comment |
In Django, union operations needs to have same columns, so with values_list you can use those specific columns only like this:
qsa = ModelA.objects.all().values('text_a', 'title')
qsb = ModelB.objects.all().values('text_a', 'title')
qsa.union(qsb)
But there is no way(that I know of) to mimic NULL in union in Django. So there are two ways you can proceed here.
First One, add an extra field in your Model with name other_column. You can put the values empty like this:
other_column = models.CharField(max_length=255, null=True, default=None)
and use the Django queryset union operations as described in here.
Last One, the approach is bit pythonic. Try like this:
a = ModelA.objects.values_list('text_a', 'title', 'other_column')
b = ModelB.objects.values_list('text_a', 'title')
union_list = list()
for i in range(0, len(a)):
if b[i] not in a[i]:
union_list.append(b[i])
union_list.append(a[i])
Hope it helps!!
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
add a comment |
In Django, union operations needs to have same columns, so with values_list you can use those specific columns only like this:
qsa = ModelA.objects.all().values('text_a', 'title')
qsb = ModelB.objects.all().values('text_a', 'title')
qsa.union(qsb)
But there is no way(that I know of) to mimic NULL in union in Django. So there are two ways you can proceed here.
First One, add an extra field in your Model with name other_column. You can put the values empty like this:
other_column = models.CharField(max_length=255, null=True, default=None)
and use the Django queryset union operations as described in here.
Last One, the approach is bit pythonic. Try like this:
a = ModelA.objects.values_list('text_a', 'title', 'other_column')
b = ModelB.objects.values_list('text_a', 'title')
union_list = list()
for i in range(0, len(a)):
if b[i] not in a[i]:
union_list.append(b[i])
union_list.append(a[i])
Hope it helps!!
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
add a comment |
In Django, union operations needs to have same columns, so with values_list you can use those specific columns only like this:
qsa = ModelA.objects.all().values('text_a', 'title')
qsb = ModelB.objects.all().values('text_a', 'title')
qsa.union(qsb)
But there is no way(that I know of) to mimic NULL in union in Django. So there are two ways you can proceed here.
First One, add an extra field in your Model with name other_column. You can put the values empty like this:
other_column = models.CharField(max_length=255, null=True, default=None)
and use the Django queryset union operations as described in here.
Last One, the approach is bit pythonic. Try like this:
a = ModelA.objects.values_list('text_a', 'title', 'other_column')
b = ModelB.objects.values_list('text_a', 'title')
union_list = list()
for i in range(0, len(a)):
if b[i] not in a[i]:
union_list.append(b[i])
union_list.append(a[i])
Hope it helps!!
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
In Django, union operations needs to have same columns, so with values_list you can use those specific columns only like this:
qsa = ModelA.objects.all().values('text_a', 'title')
qsb = ModelB.objects.all().values('text_a', 'title')
qsa.union(qsb)
But there is no way(that I know of) to mimic NULL in union in Django. So there are two ways you can proceed here.
First One, add an extra field in your Model with name other_column. You can put the values empty like this:
other_column = models.CharField(max_length=255, null=True, default=None)
and use the Django queryset union operations as described in here.
Last One, the approach is bit pythonic. Try like this:
a = ModelA.objects.values_list('text_a', 'title', 'other_column')
b = ModelB.objects.values_list('text_a', 'title')
union_list = list()
for i in range(0, len(a)):
if b[i] not in a[i]:
union_list.append(b[i])
union_list.append(a[i])
Hope it helps!!
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
answered Nov 28 '18 at 19:03
ruddraruddra
14.9k32748
14.9k32748
add a comment |
add a comment |
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