Multiple collections to store same entity

[ssharma]

Hi,

We have decided to separate our collections using namespaces. i.e. Separate collection per customer. The document structure is the same for all collections and hence we have one entity annotated as @Document in mid-tier. We use SimpleMongoRepository provided by Spring Data and hence there is no control to manipulate the collection name as it is picked up from MongoEntityInformation.getCollectionName().

I am struggling to find the code by which I can deduce which collection to pick given the same entity?

Ex.

@Document
class Foo {

@Id
String id;
String name;
String customer;

}

If customer = "A" - collection should be a.foo
If customer = "B" - collection should be b.foo etc

I have tried
Any pointers will be appreciated?

Thx,
Sid

[Oliver Gierke]

The collection name is basically determined in BasicMongoPersistentEntity.getCollectionName(). This method is called whenever we have to decide which collection to interact with. The implementation uses a SpEL expression parser to evaluate the configured String as it might contain an EL expression. So here's how you can achieve what you want:

1. Create a Spring Bean do implement the logic to determine the customer specific part

@Component("customer")
class CollectionNameStrategy {

  String part() {
    // implement here
  }
}

3. Configure a SpEL expression inside the @Document annotation

@Document("#{@customer.part() + '.accounts'}"
class Accounts {

}

@customer refers to the Spring bean named "customer" above and will call the part() method for each evaluation.

[ssharma]

Wow! As simple as it can get.

Will try and update the thread.

Thanks,
Sid

[ratishsp]

Maybe my query is more related to SPEL,
but how can I access my Accounts instance inside part() method?

@Component("customer")
class CollectionNameStrategy {

String part(Accounts accounts) {
accounts.getDetails(); //for eg
}
}

Basically, my use case is the same as mentioned by ssharma above.
In addition, I want to access instance of entity being annotated with Document inside the part() method.

Thanks,
Ratish