I have some entities which uses a slowly changing versioning by version-number without a current-version-flag. My entity looks like:
#Entity
public class MyEntity {
#Id
private long id;
private long functionalKey;
private String name;
private int version;
}
There are entries like:
{ id = 1, functionalKey = 1, name = "Test1", version = 1 }
{ id = 2, functionalKey = 18, name = "Test2", version = 1 }
{ id = 32, functionalKey = 18, name = "New Test 2", version = 2 }
How can I use Spring data to find all entries (by functionalKey) with the highest version number?
To find a single entry I can use something like MyEntity findFirstByFunctionalKeyOrderByVersionDesc(long functionalKey) or write a suitable expression statement. But I want all entities not only one! I search for something like List<MyEntity> findAllWithHighestVersionGroupedByFunctionalKey.
How is this possible?
Thanks for your support!
You cannot do that. Here is the list of things you can achieve with query methods https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.query-methods.query-creation . You should use JPQL.
Related
As stated in official documentation, it's preferable to use the Multimap return type for the Android Room database.
With the next very simple example, it's not working correctly!
#Entity
data class User(#PrimaryKey(autoGenerate = true) val _id: Long = 0, val name: String)
#Entity
data class Book(#PrimaryKey(autoGenerate = true) val _id: Long = 0, val bookName: String, val userId: Long)
(I believe a loooot of the developers have the _id primary key in their tables)
Now, in the Dao class:
#Query(
"SELECT * FROM user " +
"JOIN book ON user._id = book.userId"
)
fun allUserBooks(): Flow<Map<User, List<Book>>>
The database tables:
Finally, when I run the above query, here is what I get:
While it should have 2 entries, as there are 2 users in the corresponding table.
PS. I'm using the latest Room version at this point, Version 2.4.0-beta02.
PPS. The issue is in how UserDao_Impl.java is being generated:
all the _id columns have the same index there.
Is there a chance to do something here? (instead of switching to the intermediate data classes).
all the _id columns have the same index there.
Is there a chance to do something here?
Yes, use unique column names e.g.
#Entity
data class User(#PrimaryKey(autoGenerate = true) val userid: Long = 0, val name: String)
#Entity
data class Book(#PrimaryKey(autoGenerate = true) valbookid: Long = 0, val bookName: String, val useridmap: Long)
as used in the example below.
or
#Entity
data class User(#PrimaryKey(autoGenerate = true) #ColumnInfo(name="userid")val _id: Long = 0, val name: String)
#Entity
data class Book(#PrimaryKey(autoGenerate = true) #ColumnInfo(name="bookid")val _id: Long = 0, val bookName: String, val #ColumnInfo(name="userid_map")userId: Long)
Otherwise, as you may have noticed, Room uses the value of the last found column with the duplicated name and the User's _id is the value of the Book's _id column.
Using the above and replicating your data using :-
db = TheDatabase.getInstance(this)
dao = db.getAllDao()
var currentUserId = dao.insert(User(name = "Eugene"))
dao.insert(Book(bookName = "Eugene's book #1", useridmap = currentUserId))
dao.insert(Book(bookName = "Eugene's book #2", useridmap = currentUserId))
dao.insert(Book(bookName = "Eugene's book #3", useridmap = currentUserId))
currentUserId = dao.insert(User(name = "notEugene"))
dao.insert(Book(bookName = "not Eugene's book #4", useridmap = currentUserId))
dao.insert(Book(bookName = "not Eugene's book #5", useridmap = currentUserId))
var mapping = dao.allUserBooks() //<<<<<<<<<< BREAKPOINT HERE
for(m: Map.Entry<User,List<Book>> in mapping) {
}
for convenience and brevity a Flow hasn't been used and the above was run on the main thread.
Then the result is what I believe you are expecting :-
Additional
What if we already have the database structure with a lot of "_id" fields?
Then you have some decisions to make.
You could
do a migration to rename columns to avoid the ambiguous/duplicate column names.
use alternative POJO's in conjunction with changing the extract output column names accordingly
e.g. have :-
data class Alt_User(val userId: Long, val name: String)
and
data class Alt_Book (val bookId: Long, val bookName: String, val user_id: Long)
along with :-
#Query("SELECT user._id AS userId, user.name, book._id AS bookId, bookName, user_id " +
"FROM user JOIN book ON user._id = book.user_id")
fun allUserBooksAlt(): Map<Alt_User, List<Alt_Book>>
so user._id is output with the name as per the Alt_User POJO
other columns output specifically (although you could use * as per allUserBookAlt2)
:-
#Query("SELECT *, user._id AS userId, book._id AS bookId " +
"FROM user JOIN book ON user._id = book.user_id")
fun allUserBooksAlt2(): Map<Alt_User, List<Alt_Book>>
same as allUserBooksAlt but also has the extra columns
you would get a warning warning: The query returns some columns [_id, _id] which are not used by any of [a.a.so70190116kotlinroomambiguouscolumnsfromdocs.Alt_User, a.a.so70190116kotlinroomambiguouscolumnsfromdocs.Alt_Book]. You can use #ColumnInfo annotation on the fields to specify the mapping. You can annotate the method with #RewriteQueriesToDropUnusedColumns to direct Room to rewrite your query to avoid fetching unused columns. You can suppress this warning by annotating the method with #SuppressWarnings(RoomWarnings.CURSOR_MISMATCH). Columns returned by the query: _id, name, _id, bookName, user_id, userId, bookId. public abstract java.util.Map<a.a.so70190116kotlinroomambiguouscolumnsfromdocs.Alt_User, java.util.List<a.a.so70190116kotlinroomambiguouscolumnsfromdocs.Alt_Book>> allUserBooksAlt2();
Due to Note that Room will not rewrite the query if it has multiple columns that have the same name as it does not yet have a way to distinguish which one is necessary. the #RewriteQueriesToDropUnusedColumns doesn't do away with the warning.
if using :-
var mapping = dao.allUserBooksAlt() //<<<<<<<<<< BREAKPOINT HERE
for(m: Map.Entry<Alt_User,List<Alt_Book>> in mapping) {
}
Would result in :-
possibly other options.
However, I'd suggest fixing the issue once and for all by using a migration to rename columns to all have unique names. e.g.
I want to get one Embedded Document with a specific field (version) from an array with mongodb and spring boot.
This is the data structure:
{
"_id": 5f25882d28e40663719d0b52,
"versions": [
{
"versionNr": 1
"content": "This is the first Version of some Text"
},
{
"versionNr": 2
"content": "This is the second Version of some Text"
},
...
]
...
}
Here are my entities:
#Data
#Document(collection = "letters")
public class Letter {
#Id
#Field("_id")
private ObjectId _id;
#Field("versions")
private List<Version> versions;
}
//There is no id for embedded documents
#Data
#Document(collection = "Version")
public class Version{
#Field("content")
private String content;
#Field("version")
private Long version;
}
And this is the query that doesn't work. I think the "join" isn't correct. But can't figure out the right way.
public Optional<Version> findByIdAndVersion(ObjectId id, Long version) {
Query query = new Query(Criteria.where("_id").is(id).and("versions.version").is(version));
return Optional.ofNullable(mongoTemplate.findOne(query,Version.class,"letters"));
}
}
EDIT: This is a working Aggregation, I'm sure it isn't a pretty solution but it works
#Override
public Optional<Version> findByIdAndVersion(ObjectId id, Long version) {
MatchOperation match = new MatchOperation(Criteria.where("_id").is(id).and("versions.version").is(version));
Aggregation aggregate = Aggregation.newAggregation(
match,
Aggregation.unwind("versions"),
match,
Aggregation.project()
.andInclude("versions.content")
.andInclude("versions.version")
);
AggregationResults<Version> aggregateResult = mongoTemplate.aggregate(aggregate, "letters", Version.class);
Version version = aggregateResult.getUniqueMappedResult();
return Optional.ofNullable(mongoRawPage);
}
Query query = new Query(Criteria.where("_id").is(id).and("versions.version").is(version));
return Optional.ofNullable(mongoTemplate.findOne(query,Version.class,"letters"));
You are querying the Letter document but your entity class is specified as Version.class, since findOne from MongoDB doesn't return the subdocument by itself but rather the whole document, you need to have Letter.class as return type and filter (project) what fields to get back. So you can either project the single version subdocument that you want to receive, like so:
Query query = new Query()
.addCriteria(Criteria.where("_id").is(id).and("versions.version").is(version))
.fields().position("versions", 1);
Optional.ofNullable(mongoTemplate.findOne(query, Letter.class))
.map(Letter::getVersions)
.findFirst()
.orElse(null);
or use aggregation pipeline:
newAggregation(
Letter.class,
match(Criteria.where("_id").is(id)),
unwind("versions"),
replaceRoot("versions"),
match(Criteria.where("version").is(version))),
Version.class)
Note -- I typed this on a fly.
Is there any way that I can generate ID field as 4 digit number i.e from 1000 to 9999 in my Spring boot application. Current Id field looks like this:
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
#Column(name = "EMP_ID", nullable = false)
public short getEmp_id() {
return emp_id;
}
As of now id is getting generated from 1. But I wanted to get it generated starting from 1000 and incremented by 1 until 9999.
As suggest by Ishikawa in comments and by referring Sequence Generation from Sequence Generation did below changes:
#Id
#GenericGenerator(
name = "empid-sequence-generator",
strategy = "org.hibernate.id.enhanced.SequenceStyleGenerator",
parameters = {
#Parameter(name = "sequence_name", value = "user_sequence"),
#Parameter(name = "initial_value", value = "1000"),
#Parameter(name = "increment_size", value = "1")
}
)
#GeneratedValue(generator = "empid-sequence-generator")
#Column(name = "EMP_ID", nullable = false)
public short getEmp_id() {
return emp_id;
}
but even after that when trying to save the emp getting the below exception:
com.microsoft.sqlserver.jdbc.SQLServerException: Invalid object name 'user_sequence'.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:262)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(SQLServerStatement.java:1624)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(SQLServerPreparedStatement.java:594)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecCmd.doExecute(SQLServerPreparedStatement.java:524)
at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:7194)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:2979)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(SQLServerStatement.java:248)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(SQLServerStatement.java:223)
NOTE: It's third party database so I can't do any schema/constraint changes.I need to handle this through java code only.
My bad. Forgot to uncomment below line in application.properties.
spring.jpa.hibernate.ddl-auto = update
After uncommenting when I reboot my application it created the "user_sequence".
I've ran into a problem while developing a Spring Boot application with Criteria API.
I'm having a simple Employer entity, which contains a set of Job.ID (not entities, they're pulled out using repository when needed). Employer and Job are in many to many relationship. This mapping is only used on a purpose of finding Employee with no jobs.
public class Employer {
#ElementCollection
#CollectionTable(
name = "EMPLOYEE_JOBS"
joinColumns = #JoinColumn(name = "EMP_ID")
#Column(name = "JOB_ID")
private final Set<String> jobs = new HashSet<>(); //list of ids of jobs for an employee
}
Then I have a generic function, which returns a predicate (Specification) by a given attributePath and command for any IEntity implementation.
public <E extends IEntity> Specification<E> createPredicate(String attributePath, String command) {
return (r, q, b) -> {
Path<?> currentPath = r;
for(String attr : attributePath.split("\\.")) {
currentPath = currentPath.get(attr);
}
if(Collection.class.isAssignableFrom(currentPath.getJavaType())) {
//currentPath points to PluralAttribute
if(command.equalsIgnoreCase("empty")) {
return b.isEmpty((Expression<Collection<?>>)currentPath);
}
}
}
}
If want to get list of all employee, who currently have no job, I wish I could create the predicate as follows:
Specification<Employer> spec = createPredicate("jobs", "empty");
//or if I want only `Work`s whose were done by employer with no job at this moment
Specification<Work> spec = createPredicate("employerFinished.jobs", "empty");
This unfortunately does not works and throws following exception:
org.hibernate.hql.internal.ast.QuerySyntaxException:
unexpected end of subtree
[select generatedAlias0 from Employer as generatedAlias0
where generatedAlias0.jobs is empty]
Is there a workaround how to make this work?
This bug in Hibernate is known since September 2011, but sadly hasn't been fixed yet. (Update: this bug is fixed as of 5.4.11)
https://hibernate.atlassian.net/browse/HHH-6686
Luckily there is a very easy workaround, instead of:
"where generatedAlias0.jobs is empty"
you can use
"where size(generatedAlias0.jobs) = 0"
This way the query will work as expected.
I have a case statement in my Native query where I am attempting to override a field in my entity.
SELECT i.id, i.ONE_TO_ONE_ID, i.ANOTHER, CASE(WHEN condition THEN 'YES' WHEN another_condition THEN 'NO' ELSE 'MAYBE' END) as word ....
I am using this with JpaRepository as a native query, with pagination.
When I run the native query against my db directly, the result set looks as though I expect.
| id_value | MAPPED_ENTITY_ID_value | another value | word_value (YES) |
When I run the native query from my JpaRepository, everything works there, except word is always null. I cant' seem to figure out how to map the additional String word result to a field in my Entity.
Is there a way to get this to map? Or will I have to create an entire #SqlResultSetMapping() for all of my fields coupled with a native query? (hoping not)
UPDATE: 1
I was generalizing above. Here is my Query.
#Query(
name = "listPagedMapping",
value = "SELECT DISTINCT i.ID, i.INSTANCE_ID, i.REGION, i.CNAME_STACK_ID, i.INSTANCE_STATE, i.IP_ADDRESS, i.EC2_ROLE_NAME, i.INSTANCE_OWNER, i.IS_MASTER, i.EC2_MASTER_ID, i.CNAME, i.EC2_START_TIMESTAMP, i.PRIVATE_DNS, i.INSTANCE_NAME, i.AUTO_TERMINATE, i.AUTO_TERMINATE_DATE, i.TERMINATION_ZONE, i.ADMIN_GROUP_AD_LDAP_ID, i.USER_GROUP_AD_LDAP_ID, (CASE WHEN i.INSTANCE_OWNER=:username THEN 'OWNER' WHEN i.ADMIN_GROUP_AD_LDAP_ID IN (g.AD_LDAP_ID) THEN 'ADMIN' WHEN i.USER_GROUP_AD_LDAP_ID IN (g.AD_LDAP_ID) THEN 'USER' END) as PERMISSION FROM USER u, USER_ACCESS_GROUPS g, EC2_PROVISIONING i WHERE i.INSTANCE_OWNER=:username and i.INSTANCE_STATE in (:instanceStates) or u.username=:username and i.INSTANCE_STATE in (:instanceStates) and g.USER_ID=u.USER_ID and (i.ADMIN_GROUP_AD_LDAP_ID IN (g.AD_LDAP_ID) or i.USER_GROUP_AD_LDAP_ID IN (g.AD_LDAP_ID))",
countQuery = "SELECT count(*) FROM (SELECT DISTINCT i.* FROM USER u, USER_ACCESS_GROUPS g, EC2_PROVISIONING i WHERE i.INSTANCE_OWNER=:username and i.INSTANCE_STATE in (:instanceStates) or u.username=:username and i.INSTANCE_STATE in (:instanceStates) and g.USER_ID=u.USER_ID and (i.ADMIN_GROUP_AD_LDAP_ID IN (g.AD_LDAP_ID) or i.USER_GROUP_AD_LDAP_ID IN (g.AD_LDAP_ID))) as ug",
nativeQuery = true)
Page<Ec2Instance> findAllByPermissionUserAdminOrOwnerAndInstanceStateIn(
#Param("username")final String username,
#Param("instanceStates") final Set<String> instanceStates,
final Pageable pageable);
}
Obviously a bit more complex.
I can get it to map to the entity field with using a named query, but then I loose all the default mappings:
#JsonInclude(JsonInclude.Include.NON_NULL)
#SuppressWarnings("unused")
#Data
#AllArgsConstructor
#NoArgsConstructor
#EqualsAndHashCode(exclude={"masterNode", "workers", "associatedBuckets"})
#Entity
#Table(name = "EC2_PROVISIONING")
#SqlResultSetMapping(
name="listPagedMapping",
columns = {
#ColumnResult(name = "permission", type = String.class)
}
)
#NamedNativeQuery(
name = "listAccessibleInstances",
query = ACCESSIBLE_QUERY,
resultSetMapping = "listPagedMapping"
)
public class Ec2Instance {
....
private String permission;
#column(name = "INSTANCE_ID")
private String instanceId;
#ManyToOne
#JoinColumn(name = "EC2_MASTER_ID")
private Ec2Instance masterNode;
#Setter(AccessLevel.NONE)
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "WORKER_EC2_NODES", joinColumns = { #JoinColumn(name = "EC2_MASTER_ID") }, inverseJoinColumns = {
#JoinColumn(name = "ID") })
private Set<Ec2Instance> workers = new HashSet<>();
... More fields ..
}
I guess, I am hoping there is a way to provide a single mapping on-top of the default mapping that is done by ORM. The above code results in only a pageable of Content PERMISSION, rather than the whole entity + permission.
UPDATE: 2
Ok, so I am getting closer... Seems by removing the #ColumnResult I do get the default mapping, plus the PERMISSION field mapped over! Looks like this:
#SqlResultSetMapping(
name="listPagedMapping"
)
The last issue is it does not accept my CountQuery, and causes my tests to fail whenever a Pagination Query results with multiple pages. Looks like Spring try's to come up with its own CountQuery, which is not correct.
UPDATE: 3
To finish this off, looks like I can provide the Count Query as described here: Spring Data - Why it's not possible to have paging with native query
I will give this a go and update back.
I never got this to work quite how I wanted. I am sure I could by mapping my entire entity, but, that would have been painstaking. I ended up solving this by using NamedNativeQueries, with mapping for the additional Column as a result of my Case statement. My entity class is now annotated like:
#JsonInclude(JsonInclude.Include.NON_NULL)
#SuppressWarnings("unused")
#Data
#AllArgsConstructor
#NoArgsConstructor
#EqualsAndHashCode(callSuper = false)
#Entity
#Table(name = "EC2_PROVISIONING")
#SqlResultSetMappings({
#SqlResultSetMapping(
name = "listPagedMapping",
entities = {
#EntityResult(
entityClass = Ec2Instance.class
)
},
columns = {#ColumnResult(name = "permission", type = String.class)}
),
#SqlResultSetMapping(name = "listPagedMapping.count", columns = #ColumnResult(name = "cnt"))
})
#NamedNativeQueries({
#NamedNativeQuery(
name = "Ec2Instance.listAccessibleInstances",
query = ACCESSIBLE_QUERY,
resultClass = Ec2Instance.class,
resultSetMapping = "listPagedMapping"
),
#NamedNativeQuery(
name = "Ec2Instance.listAccessibleInstances.count",
resultSetMapping = "listPagedMapping.count",
query = ACCESSIBLE_QUERY_COUNT
)
})
We also dont need the permission field in this entity anymore. I removed that.
Then in my Repository:
Page<Object[]> listAccessibleInstances(
#Param("username")final String username,
#Param("instanceStates") final Set<String> instanceStates,
final Pageable pageable);
Thats it! Now the result of my case statement is returned with each entity.
Object[0] = original, default mapped entity.
Object[1] = permission