I have a model that has several properties. The properties can be primitive (String) or complex (Object). The user can make a query on each primitive property. I would like to know if there is an easy way to build dynamically the query. I use Java and Hibernate.
The model
public class Model {
String prop1;
Point prop2;
List<Shape> prop3;
}
Point and Shape are object that can contains primitives or objects. An example of a query would be all instances where prop1 = "A" and the coordinates are x = 3 and y = 8 and one of the shape is a circle.
prop1 = "A" and prop2.x = 3 and prop2.y and prop3.get(i).type = "Circle"; we would have to iterate on all instances of prop3.
My first idea was unmaintainable and inefficient. It consists in doing queries on all the primitive properties and then merge the results.
Get all instances where prop1 = "A"
Get all instances where prop2.x = 3
and prop3 = y;
Get all instances where one of the
Shape.type = "Circle";
Get the intersection of all 3 sets
Is there any existing library or algorithm that can solve this problem in a better (smarter) way?
Thanks
Have you looked at Criteria queries? It's a Hibernate feature for constructing queries and parameters programmatically.
If your intent is to query for entities that match all of these conditions:
prop1 = "A" and prop2.x = 3 and prop2.y and prop3.get(i).type = "Circle"
with support for association queries, then you could do something like
Criteria criteria = session.createCriteria(Model.class);
criteria.add(Restrictions.eq("prop1", "A"));
criteria.createCriteria("prop2")
.add(Restrictions.eq("x", 3));
.add(Restrictions.eq("y", 2));
criteria.createCriteria("prop3").add(Restrictions.in("type", "Circle"));
List results = criteria.list();
The real strength in Criteria queries is building the query in code rather than in a HQL string - allows you to dynamically add/set properties, etc.
Related
I am working in a Hibernate-search, Java application with an entity which has a numeric field indexed:
#Field
#NumericField
private Long orgId;
I want to get the list of entities which match with a list of Long values for this property. I used the "simpleQueryString" because it allows to use "OR" logic with char | for several objective values. I have something like this:
queryBuilder.simpleQueryString().onField("orgId").matching("1|3|8").createQuery()
After run mi application I get:
The specified query '+(orgId:1 orgId:3 orgId:8)' contains a string based sub query which targets the numeric encoded field(s) 'orgId'. Check your query or try limiting the targeted entities.
So, Can some body tell me what is wrong with this code?, Is there other way to do what I need?.
=================================
UPDATE 1:
yrodiere' answer solves the issue, but I have another doubt, I want validate whether entities match other fields, I know I can use BooleanJuntion, but then I need mix "must" and "should" usages right?. i.e.:
BooleanJunction<?> bool = queryBuilder.bool();
for (Integer orgId: orgIds) {
bool.should( queryBuilder.keyword().onField("orgId").matching(orgId).createQuery() );
}
bool.must(queryBuilder.keyword().onField("name").matching("anyName").createQuery() );
Then, I am validating that the entities must match a "name" and also they match one of the given orgIds, Am I right?
As the error message says:
The specified query [...] contains a string based sub query which targets the numeric encoded field(s) 'orgId'.
simpleQueryString can only be used to target text fields. Numeric fields are not supported.
If your string was generated programmatically, and you have a list of integers, this is what you'll need to do:
List<Integer> orgIds = Arrays.asList(1, 3, 8);
BooleanJunction<?> bool = queryBuilder.bool();
for (Integer orgId: orgIds) {
bool.should( queryBuilder.keyword().onField("orgId").matching(orgId).createQuery() );
}
LuceneQuery query = bool.createQuery();
query will match documents whose orgId field contains 1, 3 OR 8.
See https://docs.jboss.org/hibernate/search/5.11/reference/en-US/html_single/#_combining_queries
EDIT: If you need additional clauses, I'd recommend not mixing must and should in the same boolean junction, but nesting boolean junctions instead.
For example:
BooleanJunction<?> boolForOrgIds = queryBuilder.bool();
for (Integer orgId: orgIds) {
boolForOrgIds.should(queryBuilder.keyword().onField("orgId").matching(orgId).createQuery());
}
BooleanJunction<?> boolForWholeQuery = queryBuilder.bool();
boolForWholeQuery.must(boolForOrgIds.createQuery());
boolForWholeQuery.must(queryBuilder.keyword().onField("name").matching("anyName").createQuery());
// and add as many "must" as you need
LuceneQuery query = boolForWholeQuery.createQuery();
Technically you can mix 'must' and 'should', but the effect won't be what you expect: 'should' clauses will become optional and will only raise the score of documents when they match. So, not what you need here.
I am using spring-sata-mongodb 1.8.2 with MongoRepository and I am trying to use the mongo $slice option to limit a list size when query, but I can't find this option in the mongorepository.
my classes look like this:
public class InnerField{
public String a;
public String b;
public int n;
}
#Document(collection="Record")
punlic class Record{
public ObjectId id;
public List<InnerField> fields;
public int numer;
}
As you can see I have one collection name "Record" and the document contains the InnerField. the InnerField list is growing all the time so i want to limit the number of the selected fields when I am querying.
I saw that: https://docs.mongodb.org/v3.0/tutorial/project-fields-from-query-results/
which is exactly what I need but I couldn't find the relevant reference in mongorepository.
Any ideas?
Providing an abstraction for the $slice operator in Query is still an open issue. Please vote for DATAMONGO-1230 and help us prioritize.
For now you still can fall back to using BasicQuery.
String qry = "{ \"_id\" : \"record-id\"}";
String fields = "{\"fields\": { \"$slice\": 2} }";
BasicQuery query = new BasicQuery(qry, fields);
Use slice functionality as provided in Java Mongo driver using projection as in below code.
For Example:
List<Entity> list = new ArrayList<Entity>();
// Return the last 10 weeks data only
FindIterable<Document> list = db.getDBCollection("COLLECTION").find()
.projection(Projections.fields(Projections.slice("count", -10)));
MongoCursor<Document> doc = list.iterator();
while(doc.hasNext()){
list.add(new Gson().fromJson(doc.next().toJson(), Entity.class));
}
The above query will fetch all documents of type Entity class and the "field" list of each Entity class document will have only last 10 records.
I found in unit test file (DATAMONGO-1457) way to use slice. Some thing like this.
newAggregation(
UserWithLikes.class,
match(new Criteria()),
project().and("likes").slice(2)
);
I have seen that JOOQ can automatically return a POJO when we use .selectFrom(TABLE) or .fetchInto(POJO.class);
But is it possible to convert the result of a complex query into multiple POJO ?
Example :
This query will return an array of all columns into tables Support and Box. It is possible to convert them into a Support and Box Pojo ?
Result<Record> results = query.select()
.from(BOX)
.join(SUPPORT)
.on(SUPPORT.ID.equal(BOX.SUPPORT_ID))
.where(SUPPORT.ID.equal("XXXX"))
.orderBy(BOX.ID)
.fetch();
I have tested the method .intoGroups(SUPPORT.ID, Box.class) , it works fine. But I doesn't have the support object.
Instantiate to SelectSeekStep1
With aliases it's more convenient:
Box b = BOX.as("b");
Support s = SUPPORT.as("s");
SelectSeekStep1<Integer, Integer> sql = query.select(b.ID, s.ID /* other columns */)
.from(b)
.join(s)
.on(s.ID.eq(b.SUPPORT_ID))
.where(s.ID.eq("XXXX"))
.orderBy(b.ID)
;
Then just fetch what/as you need:
List<BoxRecord> boxes = sql.fetchInto(BOX);
SupportRecord support = sql.limit(1).fetchOneInto(SUPPORT);
For future readers, if you want to achieve the same behaviour with insert methods you should use:
insertInto(BOX)
.set(BOX.COLUMN1, UInteger.valueOf(1))
.set(BOX.COLUMN2, "test")
.returning()
.fetchOne()
.into(<POJO_class>.class);
i am building a shopping cart using jsp and hibernate.
i am filtering the content by brand size and price using checkboxes
the checked checkboxes are returned to the class where hql query exists.
so i want i single hql query that can handle this.
as like if one of the parameter like size is empty (means user doesnt uses it to filter the content ) than an empty string is passed to the hql query which returns any value...
so is there anything possible that all values can be retrived in where clause for empty string or some other alternative except coding different methods for different parameter...
I typically use the Criteria api for things like this... if the user does not specify a size, do not add it to the criteria query.
Criteria criteria = session.createCriteria(MyClass.class);
if(size != null && !size.isEmpty()){
criteria.add(Restrictions.eq("size", size);
}
To have multiple restrictions via an OR statement, you use Disjunction. For an AND, you use Conjunction.
Criteria criteria = session.createCriteria(MyClass.class);
Disjunction sizeDisjunction = Restrictions.disjunction();
String[] sizes = { "small", "medium", "large" };
for(int i = 0; i < sizes.length; i++){
sizeDisjunction.add(Restrictions.eq("size", sizes[i]);
}
criteria.add(sizeDisjunction );
First, good practices say that instead of passing and empty String to the query, you should pass null instead. That said, this hql should help you:
from Product p
where p.brand = coalesce(:brand, p.brand)
and p.size = coalesce(:size, p.size)
and p.price = coalesce (:price, p.price)
I have a Hibernate managed Java entity called X and a native SQL function (myfunc) that I call from a Hibernate SQL query along these lines:
SQLQuery q = hibernateSession.createSQLQuery(
"SELECT *, myfunc(:param) as result from X_table_name"
);
What I want to do is to map the everything returned from this query to a class (not necessarily managed by Hibernate) called Y. Y should contain all properties/fields from X plus the result returned by myfunc, e.g. Y could extend class X and add a "result" field.
What I've tried:
I've tried using q.addEntity(Y.class) but this fails with:
org.hibernate.MappingException: Unknown entity com.mycompany.Y
q.setResultTransformer(Transformers.aliasToBean(Y.class)); but this fails with: org.hibernate.PropertyNotFoundException: Could not find setter for some_property. X has a field called someProperty with the appropriate getter and setter but in this case it doesn't seem like Hibernate maps the column name (some_property) to the correct field name.
q.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP); returns a Map but the values are not always of the type expected by the corresponding field in X. For example fields in X of type enum and Date cannot be mapped directly from the Map returned by the SQL query (where they are Strings).
What's the appropriate way to deal with this situation?
See the chapter of the documentation about SQL queries.
You can use the addScalar() method to specify which type Hibernat should use for a given column.
And you can use aliases to map the results with the bean properties:
select t.some_property as someProperty, ..., myfunc(:param) as result from X_table_name t
Or, (and although it require some lines of code, it's my preferred solution), you can simply do the mapping yourself:
List<Object[]> rows = query.list();
for (Object[] row : rows) {
Foo foo = new Foo((Long) row[0], (String) row[1], ...);
}
This avoids reflection, and lets you control everything.
Easy. Cast the rows to Map<String, Object>:
final org.hibernate.Query q = session.createSQLQuery(sql);
q.setParameter("geo", geo);
q.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
final List<Map<String, Object>> src = q.list();
final List<VideoEntry> results = new ArrayList<VideoEntry>(src.size());
for (final Map<String, Object> map:src) {
final VideoEntry entry = new VideoEntry();
BeanUtils.populate(entry, map);
results.add(entry);
}
First of all you need to declare the entity in the hibernate configuration xml file something like this: .....
class="path to your entity"
Or you can do the same thing programatically before you make the query.