#31340: Improve expression support for __search lookup and SearchQuery
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Reporter: Baptiste Mispelon | Owner: (none)
Type: New feature | Status: new
Component: contrib.postgres | Version: 3.0
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 1
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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''(not sure whether to categorize this as a bug or a new feature)''
I've been trying to implement some kind of reverse full text search where
I store keywords in the database and I want to query models whose keywords
would match a given piece of text.
Here's a simplified model of what I'm working with:
{{{#!python
class SavedSearch(models.Model):
keywords = models.TextField()
def __str__(self):
return self.keywords
}}}
I've managed to achieve what I want in the case of the default search
configuration using annotation and wrapping things with `Value` or `Cast`:
{{{#!python
# This works
search_query = Cast('keywords', output_field=SearchQueryField())
search_vector = SearchVector(Value("lorem ipsum ...",
output_field=TextField()))
qs =
SavedSearch.objects.annotate(search=search_vector).filter(search=search_query)
}}}
But if I want to use a custom search configuration, things don't work
anymore:
{{{#!python
# This doesn't work (can't adapt type 'F')
search_query = SearchQuery(F('keywords'), config='english',
search_type='plain')
search_vector = SearchVector(Value("lorem ipsum ...",
output_field=TextField()))
qs =
SavedSearch.objects.annotate(search=search_vector).filter(search=search_query)
}}}
I'm not very familiar with the inner workings of `Lookup` objects but I
did some digging and I think I came up with a fix which involved fixing
two separate issues:
1) `SearchQuery` doesn't currently support anyting other than plain values
(`str`). Fixing this required changing both `resolve_expression()` and
`as_sql()`.
2) the `__search` lookup doesn't support things like `F` objects because
of it assumes that any value with a `resolve_expression` method must be a
`SearchQuery` object.
--
Ticket URL: <https://code.djangoproject.com/ticket/31340>
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