is null entity framework 5

Question

I have this sentence in sql server:

SELECT * FROM Documentos WHERE ( @param IS NULL OR strNOMPRO = @param )

and I do this with entity

DocumentsList = db.DOCUMENTOS
                .Where(d => d.strNOMPRO == nombre && d.strNOMPRO == null)
                .OrderByDescending(d => d.datFECCER).ToList();

if param is null this return all the registers in sql but in linq return 0 registers

How i can do this well?

Answer 1

This is an equivalent of your SQL WHERE statement:

DocumentsList = db.DOCUMENTOS
                .Where(d => nomber == null || d.strNOMPRO == nombre)
                .OrderByDescending(d => d.datFECCER)
                .ToList();

It checks parameter for null OR ( || Operator ) it checks that strNOMPRO property should be equal to parameter.

BTW thus your parameter cannot change in the middle of query, it's more efficient to add filtering condition dynamically:

var query = db.DOCUMENTOS;

if (!String.IsNullOrEmpty(nombre))
    query = query.Where(d => d.strNOMPRO == nombre);

DocumentsList = query.OrderByDescending(d => d.datFECCER).ToList();

Further readings: && Operator and || Operator