从客户端删除一个请求中的所有相关OData实体

Question

To use the Northwind database as an example, each Customer has a collection of Orders. I would like to remove all of the references between a particular Customer and all their Orders in just one request.

It looks like I can do this (based on the spec ) with DELETE http://services.odata.org/V4/Northwind/Northwind.svc/Customers('ANTON')/Orders but I'm wondering if client libraries support this.

I'm using Microsoft.OData.Client for a C# client library, Apache Olingo (v4) for Java, and BreezeJS for JavaScript. An example in any of these would be much appreciated.

EDIT: Clarified that I am just removing references , not actually deleting the entities themselves.

Answer 1

Just as swl10 said, you need to delete each reference in turn. But OData supports $batch. You can put all the delete methods in one request. Code as following:

DemoService dsc = new DemoService(new Uri("http://services.odata.org/V4/OData/(S(ut2byeiaglm424a0pbovpo33))/OData.svc/"));
var product = dsc.Products.Expand("Categories").Where(p => p.ID == 1).Single();

foreach (var c in product.Categories)
{
    dsc.DeleteLink(product, "Categories", c);
}
dsc.SaveChanges(SaveChangesOptions.BatchWithSingleChangeset);

You will find that this SaveChanges will send only one request $batch. In the payload, there are two internal DELETE request.

Answer 2

Given the previous clarifications to this question that you wish to remove the references and not the entities themselves, the answer appears to be no, you cannot do what you want to do.

In OData 4 (the specification you link to), references are obtained using $ref rather than addressing the entity directly. As a result the link you are interested in is this one:

http://services.odata.org/V4/Northwind/Northwind.svc/Customers('ANTON')/Orders/$ref

Unfortunately you can't do what you want, as the protocol says (improved for grammar):

Resource paths addressing a single entity reference can be used in DELETE requests to unrelate two entities. Resource paths addressing a collection of references can be used in DELETE requests if they are followed by the system query option $id identifying one of the entity references in the collection.

The specification writers have gone to some trouble to remove the operation you wish to perform from the protocol. You must DELETE each reference in turn, you can't delete a whole collection of references in one protocol request.

Answer 3

Do you want to just remove the reference between Customers('ANTON') and Orders, or remove Orders entities under Customers('ANTON')?

If you want later, the service should not provide this kind of Delete according to the protocol.

If you just want to remove the reference, you can try "PATCH" the "Customers('ANTON')" from the client.

Answer 4

If I understand correctly, you want to delete parent entity and all of its children? You can follow these:

1/ Deleting Entities and its Navigation Properties which is "simplest approach" suggested by Jay Traband.

2/ Another way, you can setDeleted for each entities:

var deletedEntities = Array();
Customers.entityAspect.setDeleted();
deletedEntities.push(Customers);
for( var i=0; i<Customers().Orders().length; i++){
    Customers().Orders()[i].entityAspect.setDeleted();
    deletedEntities.push(Customers().Orders()[i]);
}

manager.saveChanges(deletedEntities).then(saveSucceed).fail(saveFailed);

Above are two ways that I used. If you find any better solutions, please let me know.