There are two entities A and B relate one to many.
I want to extract "B_2" with there parent("A_1") and children("B_1", "B_2", "B_3") of there parent. So I try my code below.
from(QB.b).join(QB.b.a, QA.a).fetch().join(QA.a.bList).fetch().where(QB.b.name.eq("B_2"));
But result B.a.bList are just proxy object. And it occur to N+1 problem.
Anyone help?
For the purposes of this example, let's called the Querydsl query types for entity A a and for entity B b.
.from(a)
.innerJoin(b)
.on(a.a_id).eq(b.a_id)
.where(b.name.eq("B_2"))
.fetch();
Related
I have a type ORM query that returns five columns. I just want the company column returned but I need to select all five columns to generate the correct response.
Is there a way to wrap my query in another select statement or transform the results to just get the company column I want?
See my code below:
This is what the query returns currently:
https://i.stack.imgur.com/MghEJ.png
I want it to return:
https://i.stack.imgur.com/qkXJK.png
const qb = createQueryBuilder(Entity, 'stats_table');
qb.select('stats_table.company', 'company');
qb.addSelect('stats_table.title', 'title');
qb.addSelect('city_code');
qb.addSelect('country_code');
qb.addSelect('SUM(count)', 'sum');
qb.where('city_code IS NOT NULL OR country_code IS NOT NULL');
qb.addGroupBy('company');
qb.addGroupBy('stats_table.title');
qb.addGroupBy('country_code');
qb.addGroupBy('city_code');
qb.addOrderBy('sum', 'DESC');
qb.addOrderBy('company');
qb.addOrderBy('title');
qb.limit(3);
qb.cache(true);
return qb.getRawMany();
};```
[1]: https://i.stack.imgur.com/MghEJ.png
[2]: https://i.stack.imgur.com/qkXJK.png
TypeORM didn't meet my criteria, so I'm not experienced with it, but as long as it doesn't cause problems with TypeORM, I see an easy SQL solution and an almost as easy TypeScript solution.
The SQL solution is to simply not select the undesired columns. SQL will allow you to use fields you did not select in WHERE, GROUP BY, and/or ORDER BY clauses, though obviously you'll need to use 'SUM(count)' instead of 'sum' for the order. I have encountered some ORMs that are not happy with this though.
The TS solution is to map the return from qb.getRawMany() so that you only have the field you're interested in. Assuming getRawMany() is returning an array of objects, that would look something like this:
getRawMany().map(companyRecord => {return {company: companyRecord.company}});
That may not be exactly correct, I've taken the day off precisely because I'm sick and my brain is fuzzy enough I was making too many stupid mistakes, but the concept should work even if the code itself doesn't.
EDIT: Also note that map returns a new array, it does not modify the existing array, so you would use this in place of the getRawMany() when assigning, not after the assignment.
In case we had the model:
class Publication(models.Model):
title = models.CharField(max_length=30)
class Article(models.Model):
publications = models.ManyToManyField(Publication)
According to: https://docs.djangoproject.com/en/4.0/topics/db/examples/many_to_many/, to create an object we must have both objects saved before we can create the relation:
p1 = Publication(title='The Python Journal')
p1.save()
a1 = Article(headline='Django lets you build web apps easily')
a1.save()
a1.publications.add(p1)
Now, if we called delete in either of those objects the object would be removed from the DB along with the relation between both objects. Up until this point I understand.
But is there any way of doing that, if an Article is removed, then, all the Publications that are not related to any Article will be deleted from the DB too? Or the only way to achieve that is to query first all the Articles and then iterate through them like:
to_delete = []
qset = a1.publications.all()
for publication in qset:
if publication.article_set.count() == 1:
to_delete(publication.id)
a1.delete()
Publications.filter(id__in=to_delete).delete()
But this has lots of problems, specially a concurrency one, since it might be that a publication gets used by another article between the call to .count() and publication.delete().
Is there any way of doing this automatically, like doing a "conditional" on_delete=models.CASCADE when creating the model or something?
Thanks!
I tried with #Ersain answer:
a1.publications.annotate(article_count=Count('article_set')).filter(article_count=1).delete()
Couldn't make it work. First of all, I couldn't find the article_set variable in the relationship.
django.core.exceptions.FieldError: Cannot resolve keyword 'article_set' into field. Choices are: article, id, title
And then, running the count filter on the QuerySet after filtering by article returned ALL the tags from the article, instead of just the ones with article_count=1. So finally this is the code that I managed to make it work with:
Publication.objects.annotate(article_count=Count('article')).filter(article_count=1).filter(article=a1).delete()
Definetly I'm not an expert, not sure if this is the best approach nor if it is really time expensive, so I'm open to suggestions. But as of now it's the only solution I found to perform this operation atomically.
You can remove the related objects using this query:
a1.publications.annotate(article_count=Count('article_set')).filter(article_count=1).delete()
annotate creates a temporary field for the queryset (alias field) which aggregates a number of related Article objects for each instance in the queryset of Publication objects, using Count function. Count is a built-in aggregation function in any SQL, which returns the number of rows from a query (a number of related instances in this case). Then, we filter out those results where article_count equals 1 and remove them.
Neptune 1.0.2.1 + Gremlin + nodejs.
I have a vertext and property, e.g. Vertex - Device, property - Test, the Test property could store different type of data, e.g. number and string
Vertex 1 - Test = ['ABCD','xyz']
Vertex 2 - Test = [123,'XYZ']
I want to do a 'containing' search, e.g. Test=A, or Test=123 regardless the datatype.
I was trying
queryText = 'BC' //this throw error
or queryText = 123 //this actually works
//I expect both case should hit the result.
g.V().hasLabel('Device').or(__.has('Test', parseFloat(queryText)), __.has('Test', textP.containing(queryText)));
but get 'InternalFailureException\' error
Is it possible I can write a single query regardless the datatype?
if not possible, or at least make textP.containing work with multiple query assuming I know the datatype? right now the containing search throw error if the property contains number
It looks like you have the closing bracket in the wrong place inside the or() step. You need to close the first has step before the comma.
In your example
g.V().hasLabel('Device').or(__.has('Test', parseFloat(queryText), __.has('Test', textP.containing(queryText))));
Which should be
g.V().hasLabel('Device').or(__.has('Test', parseFloat(queryText)), __.has('Test', textP.containing(queryText)));
EDITED and UPDATED
With the corrected query and additional clarification about the data model containing different types for the same property key, I was able to reproduce what you are seeing. However, the same behavior can be seen using TinkerGraph as well as Neptune. The error message generated is is a little different but the meaning is the same. Given the fact that TinkerGraph behaves the same way I am of the opinion that Neptune is behaving consistently with the "reference" implementation. That said, this raises a question as to whether the TextP predicates should be smarter and check the type of the property before attempting the test.
gremlin> graph = TinkerGraph.open()
==>tinkergraph[vertices:0 edges:0]
gremlin> g = graph.traversal()
==>graphtraversalsource[tinkergraph[vertices:0 edges:0], standard]
gremlin> g.addV('test').property('x',12.5)
==>v[0]
gremlin> g.addV('test').property('x','ABCDEF')
==>v[2]
gremlin> g.V().hasLabel('test').or(has('x',12.3),has('x',TextP.containing('CDE')))
java.math.BigDecimal cannot be cast to java.lang.String
Type ':help' or ':h' for help.
Display stack trace? [yN]
ADDITIONAL UPDATE
I created a Jira issue so the Apache TinkerPop community can consider making a change to the TextP predicates.
https://issues.apache.org/jira/browse/TINKERPOP-2375
I need to create a query where the params are like:
queryParams.put("path", "/content/myFolder");
queryParams.put("1_property", "myProperty");
queryParams.put("1_property.operation", "exists");
queryParams.put("p.limit", "-1");
But, I need to exclude a certain path inside this blanket folder , say: "/content/myFolder/wrongFolder" and search in all other folders (whose number keeps on varying)
Is there a way to do so ? I didn't find it exactly online.
I also tried the unequals operation as the parent path is being saved in a JCR property, but still no luck. I actually need unlike to avoid all occurrences of the path. But there is no such thing:
path=/main/path/to/search/in
group.1_property=cq:parentPath
group.1_property.operation=unequals
group.1_property.value=/path/to/be/avoided
group.2_property=myProperty
group.2_property.operation=exists
group.p.or=true
p.limit=-1
This is an old question but the reason you got more results later lies in the way in which you have constructed your query. The correct way to write a query like this would be something like:
path=/main/path/where
property=myProperty
property.operation=exists
property.value=true
group.p.or=true
group.p.not=true
group.1_path=/main/path/where/first/you/donot/want/to/search
group.2_path=/main/path/where/second/you/donot/want/to/search
p.limit=-1
A couple of notes: your group.p.or in your last comment would have applied to all of your groups because they weren't delineated by a group number. If you want an OR to be applied to a specific group (but not all groups), you would use:
path=/main/path/where
group.1_property=myProperty
group.1_property.operation=exists
group.1_property.value=true
2_group.p.or=true
2_group.p.not=true
2_group.3_path=/main/path/where/first/you/donot/want/to/search
2_group.4_path=/main/path/where/second/you/donot/want/to/search
Also, the numbers themselves don't matter - they don't have to be sequential, as long as property predicate numbers aren't reused, which will cause an exception to be thrown when the QB tries to parse it. But for readability and general convention, they're usually presented that way.
I presume that your example was just thrown together for this question, but obviously your "do not search" paths would have to be children of the main path you want to search or including them in the query would be superfluous, the query would not be searching them anyway otherwise.
AEM Query Builder Documentation for 6.3
Hope this helps someone in the future.
Using QueryBuilder you can execute:
map.put("group.p.not",true)
map.put("group.1_path","/first/path/where/you/donot/want/to/search")
map.put("group.2_path","/second/path/where/you/donot/want/to/search")
Also I've checked PredicateGroup's class API and they provide a setNegated method. I've never used it myself, but I think you can negate a group and combine it into a common predicate with the path you are searching on like:
final PredicateGroup doNotSearchGroup = new PredicateGroup();
doNotSearchGroup.setNegated(true);
doNotSearchGroup.add(new Predicate("path").set("path", "/path/where/you/donot/want/to/search"));
final PredicateGroup combinedPredicate = new PredicateGroup();
combinedPredicate.add(new Predicate("path").set("path", "/path/where/you/want/to/search"));
combinedPredicate.add(doNotSearchGroup);
final Query query = queryBuilder.createQuery(combinedPredicate);
Here is the query to specify operator on given specific group id.
path=/content/course/
type=cq:Page
p.limit=-1
1_property=jcr:content/event
group.1_group.1_group.daterange.lowerBound=2019-12-26T13:39:19.358Z
group.1_group.1_group.daterange.property=jcr:content/xyz
group.1_group.2_group.daterange.upperBound=2019-12-26T13:39:19.358Z
group.1_group.2_group.daterange.property=jcr:content/abc
group.1_group.3_group.relativedaterange.property=jcr:content/courseStartDate
group.1_group.3_group.relativedaterange.lowerBound=0
group.1_group.2_group.p.not=true
group.1_group.1_group.p.not=true
I have an audited entity A. Entity A holds field 'name' and a collection of entities B (annotated as Many-to-many relationship). I created an instance of A, defined name, collection of entities B and save all it into DB. This is revision #1. Then I changed name of A and update it in DB. This is revision #2.
I use the following method to get all entities of class A at revision #2
List<A> list = getAuditReader().createQuery().forEntitiesAtRevision(A.class, 2)
.add(AuditEntity.revisionNumber().eq((int) revisionId)).getResultList();
I get entity A at revision #2, but Envers also fetches collection of entities B related to this A from revision #1. Here an example of query used by Envers:
SELECT a_b_aud.a_id, a_b_aud.b_id
FROM a_b_aud CROSS JOIN b_aud
WHERE a_b_aud.b_id=b_aud.id
AND b_aud.rev=(SELECT max(b_aud2.rev)) FROM b_aud AS b_aud2 WHERE b_aud2.rev<=2 AND b_aud.id=b_aud2.id)
AND a_b_aud.rev=(SELECT max(a_b_aud2.rev)) FROM a_b_aud AS a_b_aud2 WHERE a_b_aud2.rev<=2 AND a_b_aud.a_id=a_b_aud2.a_id AND a_b_aud.b_id=a_b_aud2.b_id)
But actually I need NULL as a collection of entities B in case of there were no changes for it at revision #2 (because of performance issue).
There are two subselects in this query. And if we have more then one collection of entities related to A (C, D, E, F) and for about 100 thousands rows for each b_aud and a_b_aud the query above takes a lot of time.
I defined entity B as not audited (i.e. did not add #Audited annotation into B) and defined A B relation by the following:
#ManyToMany
#Cascade({org.hibernate.annotations.CascadeType.SAVE_UPDATE})
#JoinTable(name = "a_b", joinColumns = #JoinColumn(name = a_id))
#Audited(targetAuditMode = RelationTargetAuditMode.NOT_AUDITED)
public Set<B> getBs();
It fixes first SUBSELECT.
But I can not find standard solution to not query B's if it do not exist for requested revision (in my case #2). So the query should look like:
SELECT a_b_aud.a_id, a_b_aud.b_id
FROM a_b_aud CROSS JOIN b_aud
WHERE a_b_aud.b_id=b_aud.id b_aud.rev=2 AND a_b_aud.rev=2
The only solution I found is using native sql query and to execute it using hibernate template. Then convert result values into entity A using ResultTransformer.
Could anybody help with this issue? Is there a standard configuration/annotation I need to add to avoid second SUBSELECT?
There's no option in Envers not to load related entities when requested. Not however, that the B entities are always loaded lazily (regardless of the annotations on the relation), so if you don't want to execute the query which loads them, simply do not access that field.
If you want better read performance, you may also want to look at the validity audit strategy, see http://docs.jboss.org/hibernate/core/4.1/devguide/en-US/html/ch15.html#d5e4085. It has faster reads, but slower writes.