I am new to hibernate and still learning the basics. I'd appreciate if someone can point me in the right direction.
I have a class:
Destination
id
name
longitude
latitude
I can read destinations based on id with something like this:
List result = session.createQuery("from Destination as d where d.id=2").list();
However, I want to read destinations from database using name. I can perhaps write something like this as a query:
String name; // name set somewhere else, say a function argument
List result = session.createQuery("from Destination as d where d.name LIKE %"+name).list();
I believe this will yield all destinations with names similar to (variable) name.
Is there something inbuilt in hibernate for such use cases or is there a better way to handle this ?
EDIT:
One thing that follows from my thought process is: name column on destination db table will have an index setup. Can I map this index in some way to the Destination class using hibernate ?
You could build your query by concatenating strings. A more elegant solution would be to use the Hibernate Criteria API.
You query would then look something like:
List result = session.createCriteria(Destination.class)
.add(Restrictions.like("name", "%" + name)
.list();
Related
As the tittle says I want to create some transactions to make queries. In my case I have Wallet and Customer classes and each of them has a type attribute for knowing what type they are. I want, for example to make a query to get all the wallets so I guess I would have to create a query like TYPE=WALLET. The code I use to query is the following.
String queryStr = "{\"selector\": {\"type\": \"wallet\"}}";
QueryResultsIterator<KeyValue> rows = stub.getQueryResult(queryStr);
The things that I don’t know who to structure the string for querying, of if there is a better way of doing this type of queries. Thanks for your help.
I'm trying to create a query using CriteriaBuilder where I need to have a predicate where the value of the predicate is like the value in the database.
Basically, I need to be able to do the following:
WHERE myTestValue LIKE columnValue
In native queries, it is an option to do that, but using the CriteriaBuilder or NamedQueries, it does not seem to work.
String myValue = "foo#bar.com";
cb.where(cb.like(myValue, root.get(Entity_.email));
Is there an option in JPA to do it like this? Or should I fall back to native queries?
EDIT
I need to be able to check if a given value matches a wildcard entry in database. So the database has a record %#bar.com%, and I need to check if my given value foo#bar.com matches to that record.
I think your params should be other way round:
cb.where(cb.like(root.get(Entity_.email),myValue);
Aditionally you may need to use add this to the second param:
cb.where(cb.like(root.get(Entity_.email),"%"+myValue+"%");
Chris found the answer. First I need to "generate" a parameter.
ParameterExpression<String> senderEmailParameter = cb.parameter(String.class, "senderEmailParameter");
Path<String> senderEmailPath = root.get(Entity_.senderEmail);
Predicate predEmail = cb.like(senderEmailParameter, senderEmailPath);
And then I need to fill the parameter in the query.
q.where(predEmail);
return em.createQuery(q).setParameter("senderEmailParameter", senderEmail).getSingleResult();
This works! Thanks Chris!
I need to optimize a query that iterates over several objects and I wanted Spring Data to let the database handle it. I want to end up with a HashMap<String,String> that looks like
2134_9877, 9877
2134_2344, 2344
3298_9437, 9437
The SQL would be select convert(varchar,b.id)+'_'+convert(varchar,a.id)',a.id from t1 a join t2 b on a.jc = b.jc
So far, I've got Whatever-QL in the repository that looks like:
#Query("SELECT new map (a.bkey, a.akey) FROM mergeTable a WHERE a.discr= ?1")
The problem is, bkey is not unique, it is only unique when paired with akey and the monstrosity that I have to feed it to wants them combined with an underscore: 2345_2177.
I have tried a.bkey.toString and ''+a.bkey and new String(a.bkey) and just string(a.bkey) (that last gives a new exception but still doesn't work) but Spring doesn't like any of these. I can find no questions asking this and it seems I cannot use SQLServer's convert() function as this ain't SQL.
How can I concatenate the Integers as Strings with an underscore in this #Query?
PS: Using the native query that's been debugged in SQLServer throws some weird alias exception in Hibernate so I think 'going native' is predetermined to be a dead end.
If I have understood it right, the 'Whatever-QL' is called JPQL, and the operator CONCAT can be used. Only the use of it, as it accepts two or more parameters depends on the JPA version you are running.
Here is the answer.
JPA concat operator
You could add a getter to your entity like this:
public String getCombinedKey(){
return a.akey + "_" + a.bkey;
}
The advantage is you could handle here null's and other things if you want and it's more reusable in case you need this in another place. If you do it just in the repository you will have to copy it everytime.
Your query would then be:
#Query("SELECT new map (a.combinedKey, a.akey) FROM mergeTable a WHERE a.discr= ?1")
Quick question... so in Hybris, I have a query similar to this:
"SELECT {CPR:pk} FROM {CategoryProductRelation as CPR}, ...."
Basically, I need to extract the Product Code and Category Code from Java which I think are available as source / target respectively but my question is, just like there's ProductModel, CategoryModel, etc. is there anything like that for CategoryProductRelation?, probably something like a generic RelationModel to simply extract source / target and go from there?
You'll need to JOIN in the entities like this
SELECT {CPR:pk}, {c.code} FROM {CategoryProductRelation as CPR
JOIN Category AS c on {CPR.source} = {c.PK} } WHERE ...
Also, you can do that in the Service Layer by simply calling your query and accessing the properties right from the relation type:
..
CategoryProductRelationModel model = result.get(0)
String categoryCode = ((CategoryModel)model.getSource()).getCode()
Depending on your amount of data, this could be pretty ineffecient.
I am using Google App Engine for a project and I need to do some queries on the database. I use the JDOQL to ask the database. In my case I want to obtain the university that contains the substring "array". I think my query has a mistake because it returns the name of universities in the alphabetical order and not the ones containing the substring.
Query query = pm.newQuery("SELECT FROM " + University.class.getName() + " WHERE name.contains("+array+") ORDER BY name RANGE 0, 5");
Could someone tell me what's wrong in my query?
Thank you for your help!
EDIT
I have a list of universities store and I have a suggestbox where we can request a university by his name. And I want to autocomplete the requested name.
App engine does not support full-text searches, you should star issue 217. However, A partial workaround is possible. And in your case I think it is a good fit.
First thing, adjust your model such that there is a lower (or upper case) version of the name as well -- I will assume it is called lname. Unless you want your queries to be case-sensitive.
Then you query like this:
Query query = pm.newQuery(University.class);
query.setFilter("lname >= startNameParam");
query.setFilter("lname < stopNameParam");
query.setOrdering("lname asc");
query.declareParameters("String startNameParam");
query.declareParameters("String stopNameParam");
query.setRange(0, 5);
List<University> results = (List<University>) query.execute(search_value, search_value + "z");
The correct way to do this is like this -
Query query = pm.newQuery(University.class,":p.contains(name)");
query.setOrdering("name asc");
query.setRange(0, 5);
List univs = q.execute(Arrays.asList(array));
(note- In this case the :p is an implicit param name you can replace with any name)