I have a simple schema "Posts have messages that have users" and I want get messages with User data.
#Entity
class User {
#Id
var id: Int = 0
var name: String = ""
var usenrame: String = ""
}
#Entity
class Messages {
#Id
var id: Int = 0
var text: String = ""
#ManyToOne()
var user = User()
}
class Post {
var id: Int = 0
#OneToMany()
#JoinColum()
var messsages: List<Messages> = ArrayList()
}
This works, but, Spring Data / Hibernate, instead of create a single query with join to get message and user, use two queries
I can use a custom repository method to get directly a message and it works fine
#Query("SELECT m FROM Message m LEFT JOIN FECTH m.user WHERE id =:id")
fun findMessageById(id: Int)
But... I don't get any way to get a Post with all messages and users...
I understand that each Post need a query to get all messages, but, I want that query get too user and not get another query for each message to get the user...
Any ideas?
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 wanted to update a nested list but I experience a strange behavior where I have to call method twice to get it done...
Here is my POJO:
#Document(collection = "company")
data class Company (
val id: ObjectId,
#Indexed(unique=true)
val name: String,
val customers: MutableList<Customer> = mutableListOf()
//other fields
)
Below is my function from custom repository to do the job which I based on this tutorial
override fun addCustomer(customer: Customer): Mono<Company> {
val query = Query(Criteria.where("employees.keycloakId").`is`(customer.createdBy))
val update = Update().addToSet("customers", customer)
val upsertOption = FindAndModifyOptions.options().upsert(true)
//if I uncomment below this will work...
//mongoTemplate.findAndModify(query, update, upsertOption, Company::class.java).block()
return mongoTemplate.findAndModify(query, update, upsertOption, Company::class.java)
}
In order to actually add this customer I have to either uncomment the block call above or call the method two times in the debugger while running integration tests which is quite confusing to me
Here is the failing test
#Test
fun addCustomer() {
//given
val company = fixture.company
val initialCustomerSize = company.customers.size
companyRepository.save(company).block()
val customerToAdd = CustomerReference(id = ObjectId.get(),
keycloakId = "dummy",
username = "customerName",
email = "email",
createdBy = company.employees[0].keycloakId)
//when, then
StepVerifier.create(companyCustomRepositoryImpl.addCustomer(customerToAdd))
.assertNext { updatedCompany -> assertThat(updatedCompany.customers).hasSize(initialCustomerSize + 1) }
.verifyComplete()
}
java.lang.AssertionError:
Expected size:<3> but was:<2> in:
I found out the issue.
By default mongo returns entity with state of before update. To override it I had to add:
val upsertOption = FindAndModifyOptions.options()
.returnNew(true)
.upsert(true)
I have a table form_header with 3 records
There are more fields in the table decided not to add it here in the post since most are irrelevant. I created a class/entity to get the count with distinct for each status in sql.
#Entity()
#Table(name = "Form_Header")
#SqlResultSetMapping(name = "myMapping",
entities = {#EntityResult(
entityClass = FormSummary.class,
fields = {#FieldResult(name = "status", column = "status"),
#FieldResult(name = "id", column = "header_id")})})
public class FormSummary {
#Id()
private Long id;
private String status;
<getter and setter>
with entity manager
List<FormSummary> results = entityManager.createNativeQuery("select DISTINCT(status), COUNT(header_id) as header_id from Form_Header where is_deleted = 0 group by status order by status", "myMapping").getResultList();
for (FormSummary x : results) {
System.out.println("ABC " + x.getId());
System.out.println("ABC " + x.getStatus());
}
Issue is the sysout is showing this
instead of this
status header_id
APPROVE 1
DRAFT 1
SUBMITTED 1
Whats even weird is if I add an extra record in the table with the same status
I will get the correct data in my jpa
Am I missing something in my code or a possible bug with SqlResultSetMapping?
I'm importing historical football (or soccer, if you're from the US) data into a Neo4j database using a spring boot application (2.1.6.RELEASE) with the spring-boot-starter-data-neo4j dependency and a standalone, locally running 3.5.6 Neo4j database server.
But for some reason searching for an entity by a simple property and an attached, referenced entity, does not work, althought the relation is present in the database.
This is the part of the model, that is currently giving me a headache:
#NodeEntity(label = "Season")
open class Season(
#Id
#GeneratedValue
var id: Long? = null,
#Index(unique = true)
var name: String,
var seasonNumber: Long,
#Relationship(type = "IN_LEAGUE", direction = Relationship.OUTGOING)
var league: League?,
var start: LocalDate,
var end: LocalDate
)
#NodeEntity(label = "League")
open class League(
#Id
#GeneratedValue
var id: Long? = null,
#Index(unique = true)
var name: String,
#Relationship(type = "BELONGS_TO", direction = Relationship.OUTGOING)
var country: Country?
)
(I left out the Country class, as I'm pretty sure that it is not part of the problem)
To allow running the import more than once, I want to check if the corresponding entity is already present in the database and only import newer ones. So I added the following method SeasonRepository:
open class SeasonRepository : CrudRepository<Season, Long> {
fun findBySeasonNumberAndLeague(number: Long, league: League): Season?
}
But it is giving me a null result instead of the existing entity on consecutive runs, hence I get duplicates in my database.
I would have expected spring-data-neo4j to reduce the passed League to its Id and then have a generated query that looks somewhat like this:
MATCH (s:Season)-[:IN_LEAGUE]->(l:League) WHERE id(l) = {leagueId} AND s.seasonNumber = {seasonNumber} WITH s MATCH (s)-[r]->(o) RETURN s,r,o
but when I turn on finer logging on the neo4j package I see this output in the log file:
MATCH (n:`Season`) WHERE n.`seasonNumber` = { `seasonNumber_0` } AND n.`league` = { `league_1` } WITH n RETURN n,[ [ (n)-[r_i1:`IN_LEAGUE`]->(l1:`League`) | [ r_i1, l1 ] ] ], ID(n) with params {league_1={id=30228, name=1. Bundesliga, country={id=29773, name=Deutschland}}, seasonNumber_0=1}
So for some reason, spring-data seems to think, that the league property is a simple / primitive property and not a full releation, that needs to be resolved by the id (n.league= {league_1}).
I only got it to work, by passing the id of the league, and providing a custom query using the #Query annotation but I actually thought, that it would work with spring-data-neo4j out of the box.
Any help appreciated. Let me know if you need more details.
Spring Data Neo4j does not support objects as parameters at the moment. It is possible to query for properties on related entities/nodes e.g. findBySeasonNumberAndLeagueName if this is a suitable solution.
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