Getting Dapper to return an empty string instead of a null string

Question

I know it\'s kind of the wrong thing to do, but I\'m dealing with a legacy codebase that has NULLS when it means empty strings and vice versa.

I can\'t immediately

Answer 1

Dapper doesn't call any setter when it sees a null, so options might include:

• set the default value to "" in the constructor
• check for null in the accessor

So:

public class SomeDto
{
    public SomeDto()
    {
        Name = "";
    }
    public string Name {get;set;}
}

or:

public class SomeDto
{
    private string name;
    public string Name { get {return name ?? "";} set {name = value;} }
}

However, this only applies to reading values; I can't think of a nice way to get dapper to turn "" into null when passing the dto in as the parameter object; options include:

• creating an anon-type, substituting "" to null (perhaps write a string NullIfBlank(this string s) extension method)
• having a shim property on the type that returns null in place of "", and have your database query bind to @NameOrNull rather than @Name