How to write an OData call to get all entities with a specific property equal to an empty array

Question

I have an api that uses REST/OData. All of the products have an expandable property that is an array of objects. But some of the products are missing these objects. I need to find which ones by filtering out all the ones that have content in the arrays, and returning all of the ones that have an empty array.

Here's the structure of a normal object:

{
    "odata.metadata": "https://myapi.com/$metadata#Products",
    "value": [
        {
            "Name": "myName"
            "StatusId": 1,
            "Id": 88,
            "DateCreated": "2015-01-22T14:30:00.6611598",
            "DateModified": "2015-01-22T23:48:41.4590534",
            "ProductPropertyArray": [
                {
                    "Property1": 1,
                    "Property2": 3
                },
                {
                    "Property1": 4,
                    "Property2": 2
                }
            ]
        }
    [
}

I've tried:

myapi.com/Products?$filter=length(ProductPropertyArray) eq 0

But this doesn't work because it wants a string.

I've also tried

myapi.com/Products?$filter=ProductPropertyArray eq null

But that doesn't work either.

Answer 1

像这样调用api时，请在头脑中使用Prefer = Prefer ='odata.include-annotations =“ *”，return = representation'