Thursday, July 20, 2017

How to concat two columns of table django model

By Hường Hana 5:30 AM , , Leave a Comment

I am implementing search in my project what I want is to concat to column in where clause to get results from table.

Here is what I am doing:

from django.db.models import Q  if 'search[value]' in request.POST and len(request.POST['search[value]']) >= 3:     search_value = request.POST['search[value]'].strip()      q.extend([         Q(id__icontains=request.POST['search[value]']) |         (Q(created_by__first_name=request.POST['search[value]']) & Q(created_for=None)) |         Q(created_for__first_name=request.POST['search[value]']) |         (Q(created_by__last_name=request.POST['search[value]']) & Q(created_for=None)) |         Q(created_for__last_name=request.POST['search[value]']) |         (Q(created_by__email__icontains=search_value) & Q(created_for=None)) |         Q(created_for__email__icontains=search_value) |         Q(ticket_category=request.POST['search[value]']) |         Q(status__icontains=request.POST['search[value]']) |         Q(issue_type__icontains=request.POST['search[value]']) |         Q(title__icontains=request.POST['search[value]']) |         Q(assigned_to__first_name__icontains=request.POST['search[value]']) |      ])

Now I want to add another OR condition like:

CONCAT(' ', created_by__first_name, created_by__last_name) like '%'search_value'%'

But when I add this condition to the queryset it becomes AND

where = ["CONCAT_WS(' ', profiles_userprofile.first_name, profiles_userprofile.last_name) like '"+request.POST['search[value]']+"' "]             tickets = Ticket.objects.get_active(u, page_type).filter(*q).extra(where=where).exclude(*exq).order_by(*order_dash)[cur:cur_length]

How do I convert this into an OR condition?

3 Answers

Answers 1

Advanced filters can be solved by Q() object and Query expressions like Func(), Value() and F(). The only used trick is a Custom Lookup "rhs_only" that uses the right-hand-side of the lookup and ignores the left side, because it is easier to use all concatenated fields directly on the right side. A memorable function concat_like encapsulates that all to be easily used in queries.

from django.db.models import F, Func, Lookup, Q, Value from django.db.models.fields import Field  def concat_like(columns, pattern):     """Lookup filter: CONCAT_WS(' ', column_0, column_1...) LIKE pattern"""     lhs = '%s__rhs_only' % columns[0]     expr = Func(*(F(x) for x in columns), template="CONCAT_WS(' ', %(expressions)s)")     return Q(**{lhs: Like(expr, Value(pattern))})  class Like(Func):     def as_sql(self, compiler, connection):         arg_sql, arg_params = zip(*[compiler.compile(x) for x in self.source_expressions])         return ("%s LIKE '%s'" % tuple(arg_sql)), arg_params[0] + arg_params[1]  @Field.register_lookup class RhsOnly(Lookup):     """Skip the LHS and evaluate the boolean RHS only"""     lookup_name = 'rhs_only'      def as_sql(self, compiler, connection):         return self.process_rhs(compiler, connection)

All boolean expression and related objects are supported by this code. All arguments are correctly escaped.

Example usage:

>>> qs = MyModel.objects.filter(Q(id=1) | concat_like(('first_name', 'surname'), 'searched')) >>> str(qs.query)   # sql output simplified here "SELECT .. WHERE id=1 OR (CONCAT_WS(' ', first_name, surname) LIKE 'searched')"

Answers 2

Relevant documentation:

You can reference annotated fields from inside the filter method. As such, you can filter against two concatenated fields and add it as another OR condition like this:

from django.db.models import F, Func, Value  # Because we added user_full_name as an annotation below, # we can refer to it in the filters q.extend([     Q(id__icontains=request.POST['search[value]']) |     (Q(created_by__first_name=request.POST['search[value]']) & Q(created_for=None)) |     Q(created_for__first_name=request.POST['search[value]']) |     (Q(created_by__last_name=request.POST['search[value]']) & Q(created_for=None)) |     Q(created_for__last_name=request.POST['search[value]']) |     (Q(created_by__email__icontains=search_value) & Q(created_for=None)) |     Q(created_for__email__icontains=search_value) |     Q(ticket_category=request.POST['search[value]']) |     Q(status__icontains=request.POST['search[value]']) |     Q(issue_type__icontains=request.POST['search[value]']) |     Q(title__icontains=request.POST['search[value]']) |     Q(assigned_to__first_name__icontains=request.POST['search[value]']) |     Q(user_full_name__icontains=request.POST['search[value]'])  # <------ ])   # Add the annotation to your queryset # I'm not actually sure what the related_name or field_name for your user # profiles are, so I'm pretending that tickets have a profile foreignkey field # to where the first_name and last_name fields are user_full_name_expr = Func(Value(' '), F('profile__first_name'), F('profile__last_name'), function='CONCAT_WS')  # The next two lines can be combined as long as the annotation comes first. tickets = Ticket.objects.annotate(user_full_name=user_full_name_expr) tickets = tickets.get_active(u, page_type).filter(*q).exclude(*exq).order_by(*order_dash)[cur:cur_length]

For fun, here's a working example based on the User model.

from django.contrib.auth.models import User from django.db.models import F, Func, Value  User.objects.create(username='john', first_name='John', last_name='Jingleheimer-Schmidt') User.objects.create(username='mike', first_name='Michael', last_name='Finnigan')  foo = User.objects.annotate(full_name=Func(Value(' '), F('first_name'), F('last_name'), function='CONCAT_WS')) print(foo.filter(full_name__icontains='john'))  # outputs: [<User: john>]

Answers 3

What you need is, for create search FullText. I recommend use (http://haystacksearch.org/)

See documentation of Django (https://docs.djangoproject.com/en/1.11/ref/contrib/postgres/search/)

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