How to expand multiple properties on OData

Question

Consider I have this OData expression:

http://services.odata.org/northwind/northwind.svc/Categories?
    $expand=Products/Category

It will correctly expand the Products.Category.

Now I want to expand another property too. For example 'Products.Supplier`.

I've tried duplicating the $expand usage:

http://services.odata.org/northwind/northwind.svc/Categories?
    $expand=Products/Category
    &$expand=Products/Supplier

but it failed returning this error:

Query parameter '$expand' is specified, but it should be specified exactly once.

Answer 1

According to OData ABNF, expand syntax should be:

expand = '$expand' EQ expandItem *( COMMA expandItem )

Which amounts to:

$expand=expandItem1,expandItem2,expandItem3,...

So please try:

http://services.odata.org/northwind/northwind.svc/Categories?$expand=Products/Category,Products/Supplier

---

For more information, see:

http://www.odata.org/documentation/odata-version-2-0/uri-conventions/#ExpandSystemQueryOption

Answer 2

You can also try this syntax for expanding multiple levels:

$expand=Products($expand=Category),...

This works well with MS OData implementation in WebAPI.