odata - disable paging in custom provider

Question

I have created an OData wrapper layer to my existing data engine. All operations including: sorting filtering and paging are passed directly to my existing engine and retrieve the needed data.

problem is with the paging: second page results are retrieved from my existing engine, but later odata skips the amount of "skip=" and sends empty collection to the client. for example: I am paging "Products", there are 100 in the DB. First page gets 10 to the server, skips 0 and sends the 10 to the client. second page gets 10 to the server, skips 10 and sends nothing to the customer.

Is there a way around this?

p.s. Page size my vary according to client request. I cannot write it hardcoded on the server.

Could you please post the URL queries for the first and second page? Also the expression tree executed against your provider for these queries would help as well. — Vitek Karas MSFT
first page query:/Products?&$orderby=product_id asc&$top=10 second page query: /Products?&$orderby=product_id asc&$top=10&$skip=10 — user355289
That looks correct (From the client perspective). So you're saying that even if the query has $skip=10, WCF DS actually skips over 100 rows? Could you please check what is the query (LINQ expression tree) executed against your custom provider for the second query? — Vitek Karas MSFT
No, It skips 10. but after I retrieved records 11-20 all I have to in my server is 10 records, and they are skipped... I will try to get a string out of the expression when debugging. — user355289
I am trying to get something out of System.Linq.Expressions.Expression that I can post here, but not sure where to look as it seems very complex . so my real question here is - how do I read System.Linq.Expressions.Expression and how do I change it to remove the "skip" part — user355289

user355289 user355289 · Accepted Answer · 2013-05-26T14:18:54

I found this method call in my code and added the first 2 lines:

public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
    {
        if (expression.ToString().Contains(".Skip("))
            expression = (expression as MethodCallExpression).Arguments[0];

        return new DSPLinqQuery<TElement>(this, expression);
    }

this way the larger expression being built will not contain skip(10)

odata - disable paging in custom provider

1 Answers