如何连接表django模型的两列

Question

我正在我的项目中实现搜索，我想要的是连接到 where 子句中的列以从表中获取结果。

这是我正在做的事情：

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]']) |

    ])

现在我想添加另一个 OR 条件，例如：

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

但是当我将此条件添加到查询集时，它变为 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]

如何将其转换为 OR 条件？

Answer 1

高级过滤器可以通过以下方式解决 Q() object 和 Query expressions 像 Func()、Value() 和 F()。 唯一使用的技巧是 Custom Lookup "rhs_only" 使用查找的右侧并忽略左侧，因为直接在右侧使用所有连接字段更容易。一个令人难忘的函数concat_like 封装了所有这些，以便在查询中轻松使用。

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)

此代码支持所有布尔表达式和相关对象。所有参数均已正确转义。

示例用法：

>>> 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')"  

Answer 2

相关文档：

• https://docs.djangoproject.com/en/1.11/ref/models/expressions/#func-expressions
  • 另见... Value() 和 F()
• https://docs.djangoproject.com/en/1.11/topics/db/aggregation/#aggregations-and-other-queryset-clauses

您可以从过滤器方法中引用带注释的字段。因此，您可以过滤两个连接字段并将其添加为另一个 OR 条件，如下所示：

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]

---

为了好玩，这里有一个基于用户模型的工作示例。

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>]

Answer 3

您需要的是，创建搜索全文。我推荐使用 (http://haystacksearch.org/)

查看 Django 文档 (https://docs.djangoproject.com/en/1.11/ref/contrib/postgres/search/)