I need to build a simple username search. I want to have it ordered by usernames that start with the query and then after usernames that contain the string.
if I have a list of usernames like this
john
matt
atom
atyler
mrmat
I want it to order like so:
atom
atyler
matt
mrmat
How would I achieve this in a single query? Right now I have
users = User.objects.filter(Q(name__istartswith='at') | Q(name__icontains='at'))
But this returns:
matt
mrmat
atyler
atom
class Z(Func):
function = 'ilike'
template = "%(expressions)s %(function)s 'in%%%%'"
for u in User.objects.filter(username__icontains('in'))\
.annotate(q=Z(F('username')))\
.order_by('-q', 'username'):
print u.username, u.q
ilike is a postgres extension, for mysql you'll have to either sacrifice case insensitivity or write the corresponding workaround for that.
The "old" way:
User.objects.filter(username__icontains='at')\
.extra(select={'q': "username ilike 'at%%%%'"},
order_by=['-q', 'username'])
This code block filters the queryset and orders it as required by OP.
Also the note about ilike from the second answer applies here.
Related
How to get all field from DB where value have number?
Example valid: 1test, tes1t, test1
I suppose something like this: field__contains
You can do this with a regex query.
Model.objects.filter(value__regex=r'\d')
Use icontains: django docs.
objs = Model.objects.filter(value__icontains="1")
The equivalent of doing an sql ILIKE "%1%" (case insensitive)
contains may work just as well actually if it's a number, that's a simple LIKE
Edit: To answer your comment yes you'd need to loop over the numbers. See this question
let's say that I have an Address model with a postcode field. I can lookup addresses with postcode starting with "123" with this line:
Address.objects.filter(postcode__startswith="123")
Now, I need to do this search the "other way around". I have an Address model with a postcode_prefix field, and I need to retrieve all the addresses for which postcode_prefix is a prefix of a given code, like "12345". So if in my db I had 2 addresses with postcode_prefix = "123" and "234", only the first one would be returned.
Something like:
Address.objects.filter("12345".startswith(postcode_prefix))
The problem is that this doesn't work.
The only solution I can come up with is to perform a filter on the first char, like:
Address.objects.filter(postcode_prefix__startswith="12345"[0])
and then, when I get the results, make a list comprehension that filters them properly, like this:
results = [r for r in results if "12345".startswith(r.postcode_prefix)]
Is there a better way to do it in django?
Edit: This does not answer the original question but how to word a query the other way around.
I think what you are trying to do with your "something like" line is properly written as this:
Address.objects.filter(postcode__startswith=postcode_prefix)
In SQL terms, what you want to achieve reads like ('12345' is the postcode you are searching for):
SELECT *
FROM address
WHERE '12345' LIKE postcode_prefix||'%'
This is not really a standard query and I do not see any possibility to achieve this in Django using only get()/filter().
However, Django offers a way to provide additional SQL clauses with extra():
postcode = '12345'
Address.objects.extra(where=["%s LIKE postcode_prefix||'%%'"], params=[postcode])
Please see the Django documentation on extra() for further reference. Also note that the extra contains pure SQL, so you need to make sure that the clause is valid for your database.
Hope this works for you.
Bit of a mouthful but you can do this by annotating your search value and then filtering against it. All happens pretty quickly in-database.
from django.db.models import Value as V, F, CharField
Address.objects.exclude(
postcode_prefix=''
).annotate(
postcode=Value('12345', output_field=CharField())
).filter(
postcode__startswith=F('postcode_prefix')
)
The exclude is only necessary if postcode_prefix can be empty. This would result in an SQL like '%', which would match every postcode.
I'm sure you could do this via a nice templated function these days too... But this is clean enough for me.
A possible alternative. (Have no idea how it compares to the accepted solution with a column as the second param to like, in execution time)
q=reduce(lambda a,b:a|b, [Q(postcode__startswith=postcode[:i+1]) for i in range(len(postcode))])
Thus, you generate all prefixes, and or them together...
The raw SQL query that would do that you need looks something like this:
select * from postal_code_table where '1234567' like postal_code||'%'
This query will select any postal_code from your table that is a substring of '1234567' and also must start from begining, ie: '123', '1234', etc.
Now to implement this in Django, the preferred method is using a custom look up:
from django.db.models.fields import Field
from django.db.models import Lookup
#Field.register_lookup
class LowerStartswithContainedBy(Lookup):
'''Postgres LIKE query statement'''
lookup_name = 'istartswithcontainedby'
def as_sql(self, compiler, connection):
lhs, lhs_params = self.process_lhs(compiler, connection)
rhs, rhs_params = self.process_rhs(compiler, connection)
params = lhs_params + rhs_params
return f"LOWER({rhs}) LIKE LOWER({lhs}) || '%%'", params
Now you can write a django query such as the following:
PostCode.objects.filter(code__istartswithcontainedby='1234567')
Similarly, if you are just looking for substring and do not require the startswith condition, simply modify the return line of as_sql method to the following:
return f"LOWER({rhs}) LIKE '%%' || LOWER({lhs}) || '%%'", params
For more detailed explanation, see my git gist Django custom lookup
A. If not the issue https://code.djangoproject.com/ticket/13363,
you could do this:
queryset.extra(select={'myconst': "'this superstring is myconst value'"}).filter(myconst__contains=F('myfield'))
Maybe, they will fix an issue and it can work.
B. If not the issue 16731 (sorry not providing full url, not enough rep, see another ticket above) you could filter by fields that added with '.annotate', with creation of custom aggreation function, like here:
http://coder.cl/2011/09/custom-aggregates-on-django/
C. Last and successful. I have managed to do this using monkeypatching of the following:
django.db.models.sql.Query.query_terms
django.db.models.fields.Field.get_prep_lookup
django.db.models.fields.Field.get_db_prep_lookup
django.db.models.sql.where.WhereNode.make_atom
Just defined custom lookup '_starts', which has reverse logic of '_startswith'
again I would like to search for duplicates in my models, but now slightly different case.
Here are my models:
class Concept(models.Model):
main_name = models.ForeignKey(Literal)
...
class Literal(models.Model):
name = models.Charfield(...)
concept = models.ForeignKey(Concept)
...
And now the task I'm trying to achieve:
Select all literals that are NOT main_names, that have the same name for the same concept.
For example if I have literals:
[{id:1, name:'test', concept:1}, {id:2, name:'test', concept:1}]
and concepts:
[{id:1, main_name:1}]
Then in result I should get literal with the ID=2.
It sounds to me as though you want to execute a SQL query something like this:
SELECT l1.* FROM myapp_literal AS l1,
myapp_literal AS l2
WHERE l1.id <> l2.id
AND l1.name = l2.name
AND l1.concept = l2.concept
AND l1.id NOT IN (SELECT main_name FROM myapp_concept)
GROUP BY l1.id
Well, in cases where the query is too complex to easily express in Django's query language, you can always ask Django to do a raw SQL query—and this may be one of those cases.
If I understand your question you want:
All Literal objects that are not ForeignKey'd to Concept.
From that set, select those where the name and the concept is the same.
If so, I think this should work:
For the first part:
q = Literal.objects.exclude(pk__in=Concept.objects.values_list('id', flat=True))
EDIT:
Based on excellent feedback from Jan, I think for #2 you would need to use raw SQL.
As per the title, how would one match on a regular expression with the Doctrine 2 query builder? Basically I'm trying to generate unique slugs.
Here is my current implementation. I generate the slug. I then check to see if there are any slugs in use like this slug. If there are, I will append a -{number} to the end of the slug where {number} is the lowest number not already in use.
$qb->select(array('partial o.{id, slug}'))
->from('Foo\Bar\Entity\Object', 'o')
->where($qb->expr()->like('o.slug', ':slug'));
$slug = new SlugNormalizer($text);
$qb->setParameter('slug', $slug->__toString().'-%');
The problem here is LIKE slug% could match foo-bar-1, foo-bar-2, AND foo-bar-not-the-same-slug. What would be cleaner is a regex looking for REGEX slug-(\d+) or something similar.
Any way to do this with the Doctrine 2 query builder?
install the DoctrineExtensionsBundle:
composer require beberlei/doctrineextensions
add the REGEXP configuration - update your app/config.yml
doctrine:
orm:
dql:
string_functions:
regexp: DoctrineExtensions\Query\Mysql\Regexp
where ever your QueryBuilder is do this:
$qb = $this->createQueryBuilder('x');
return $qb->andWhere('REGEXP(x.your_property, :regexp) = true')
->setParameter('regexp', '[[:digit:]]{3}') // insert your own regex here
->getQuery()->getResult();
and don't forget to use SQL compatible regexes
REGEXP is a vendor specific function so Doctrine itself doesn't support it. Plus it's not a function so much as a comparison operator (see this answer). But you can use the function on the field to compare with another value. DoctrineExtensions (written by a contributor to doctrine) has code to enable regular expression in MySQL.
Example from the File:
$query = $this->getEntityManager()->createQuery('SELECT A FROM Entity A WHERE REGEXP(A.stringField, :regexp) = 1');
$query->setParameter('regexp', '^[ABC]');
$results = $query->getArrayResult();
If you don't want to use DoctrineExtensions, you can write your own by following this blog post, or you can look at the code for this Doctrine extension and write your own custom DQL function.
I have confirmed that REGEXP using DoctrineExtensions works great for my needs!
Not tested (for MySQL):
$qb->where(new Doctrine\ORM\Query\Expr\Comparison(
'o.slug', 'REGEXP', ':slug')
);
$qb->setParameter('slug', '^'.$slug->__toString().'-[[:digit:]]+$');
I did like this
$query->andWhere('REGEXP(r.status, :text) = 1')
->orWhere('REGEXP(r.comment, :text) = 1')
->setParameter('text',MY REGULAR EXP);
I'm implementing a simple LIKE search on my Django website and what I currently use is the following code:
from django.db.models import Q
posts = Post.objects.filter(Q(title__icontains=query)|Q(content__icontains=query))
Where query is a string. This results in a LIKE SQL statement and works quite okay. Now I'd also like to split my search query into terms or words:
words = query.split(' ')
So words now contains a list of words, and I'd like to achieve an SQL statement similar to:
SELECT ... FROM foo WHERE `title` ILIKE '%word1%' OR `title` ILIKE '%word2%'
OR `content` ILIKE '%word1%' OR `content` ILIKE '%word2%'
And in case there are more than two words I'd like the statement to grow listing all entries by every word.
Any ideas? Thanks!
reduce(operator.or_, sequence_of_Q_objects)