Handle resource links of resources inlined using @Projection [DATAREST-302]

[spring-projects-issues]

Szymon Stasik opened DATAREST-302 and commented

Having inlined resource it would be usefull to have access to its resources. eg. for

{
  "_links" : {
    "self" : {
      "href" : "http://127.0.0.1:8080/api/orders/200"
    },
    "shippingType" : {
      "href" : "http://127.0.0.1:8080/api/orders/200/shippingType"
    },
    "customer" : {
      "href" : "http://127.0.0.1:8080/api/orders/200/customer"
    }
  }
}

and

{
  "firstName" : "John",
  "lastName" : "Doe",
  "_links" : {
    "self" : {
      "href" : "http://127.0.0.1:8080/api/customers/213"
    },
    "address" : {
      "href" : "http://127.0.0.1:8080/api/customers/213/address"
    }
  }
}

after using projection to inline customer the reference to customer.address is being lost:

{
  "customer" : {
    "firstName" : "John",
    "lastName" : "Doe",
  }
  "_links" : {
    "self" : {
      "href" : "http://127.0.0.1:8080/api/orders/200{?projection}",
      "templated" : true
    },
    "shippingType" : {
      "href" : "http://127.0.0.1:8080/api/orders/200/shippingType"
    },
    "customer" : {
      "href" : "http://127.0.0.1:8080/api/orders/200/customer"
    }
  }
}

---

Affects: 2.1 RC1 (Dijkstra)

Issue Links:

• DATAREST-464 Links don't get inserted for inlined embedded associations
  ("is duplicated by"_)

Referenced from: commits 2697c6a, 5895b5e, b4bfee3

Backported to: 2.3.1 (Fowler SR1), 2.2.3 (Evans SR3)

1 votes, 6 watchers

[spring-projects-issues]

Szymon Stasik commented

I guess natural solution would be to include _links within inlined "customer" property. Also another thing is coming to my mind - using eg. propertyName.projection parameter it might be possible to define nested inlining

[spring-projects-issues]

Ruslan Stelmachenko commented

I think Szymon Stasik is right. But we lose not only the reference to customer.address but also the reference to self. It's actually sometimes very important to know which customer it is.

For example we want to show the html table in which everty row is customer name and every cell is order.

1. We load all customers GET /api/customers/.
2. We load all orders GET /api/orders/

Now how we can understand from JavaScript what order whose?
From first request we get real id of every customer as customer._links.self.href: "/api/customers/CUSTOMER_ID".
From second request we get links to customers like this order._links.customer.href: "/api/orders/ORDER_ID/customer".

We can't connect loaded orders with their customers somehow.
With projections we can load orders with customers inlined but again with no links so we cannot know hyper-id of a customer.

It is real showstopper in my use case and makes me use DB ID's instead of hyper-id's to identify resources from JS.

P.S. Of course even if this proposition would be implemented we should have some parameter to explicitly specify that we need or don't need _links in inlined resources. Including them always can greatly increase the payload if we GET the collection with inlined collection for example

[spring-projects-issues]

Johannes Hiemer commented

Inlined projection entities do not contain any hrefs, which makes it nearly impossible to follow the entity with hal. This should be added in my opinion

[spring-projects-issues]

Oliver Drotbohm commented

This should be fixed guys. We now add both self links for projected entities and also keep the link pointing to the association.

I back-ported the change as far as id applied cleanly. As an example see this gist to document the before and after stage

[spring-projects-issues]

Johannes Hiemer commented

Just tested it with 2.3.1.BUILD-SNAPSHOT and no links inside projected entities. :-(

[spring-projects-issues]

Johannes Schmidt commented

I tried several version of spring data rest, but not links for inline objects in projections are shown.

Spring Boot: 1.3.2 / 1.2.7
releasetrain: Gosling SR2A, SR1

Is it possible to display the links at the moment?

[spring-projects-issues]

George T commented

Tested also on 2.4.2. No links are returned.

[spring-projects-issues]

Johannes Schmidt commented

Is it possible to reopen this issue?

[spring-projects-issues]

Oliver Drotbohm commented

It unfortunately is not as it appears in change logs of already released versions. Feel free to open a new ticket if you like to see things improved