使用输出参数调用Entity Framework过程时出错

Question

I am attempting to Salt my Passwords.

Here is my sproc which returns my pw as an nvarchar(512):

alter proc [dbo].g_GetPWFromEmail
@emailAddress nvarchar(50),
@EncrPass nvarchar(512) OUTPUT

as
if ((Select count(*) from users  where emailAddress = @emailAddress) > 0)
begin
    select @EncrPass =  password 
    from users 
    where emailAddress = @emailAddress
end
else
begin
    select @EncrPass =  ''
end

Here is what was scaffolded in the emdx file:

public virtual ObjectResult<string> g_GetPWFromEmail(string emailAddress, ObjectParameter encrPass)
{
    var emailAddressParameter = emailAddress != null ?
        new ObjectParameter("emailAddress", emailAddress) :
        new ObjectParameter("emailAddress", typeof(string));

    return ((IObjectContextAdapter)this).ObjectContext.ExecuteFunction<string>("g_GetPWFromEmail", emailAddressParameter, encrPass);
}

And when I call it it errors out... not sure how to call this - here is what I have so far:

//Pull Current Encrypted Password from DB
string DbPw = "";
ObjectParameter DBPW1 = null;
var DbPassWord =  databaseManager.g_GetPWFromEmail(model.Username, DBPW1).ToList();
if (DbPassWord != null && DbPassWord.Count() > 0)
{
     DbPw = Convert.ToString(DBPW1);
}

How do I call this to return my hashed pw from the DB? I know there is a better way, but have tried several ways and can't get the syntax quite right.

Answer 1

If your use case is really this simple, then regular LINQ-to-Entities will work, assuming you've set up your tables as entities:

using (var context = new MyContext()) {
    string encryptedPassword = context.Users
        .Where(u => u.emailAddress == emailAddress)
        .Select(u => u.password)
        .SingleOrDefault();
}

Answer 2

You pass in a null reference ( DPBW1 ) into the method. Therefore, the method cannot update that reference with the output value.

ObjectParameter DBPW1 = null;
var DbPassWord =  databaseManager.g_GetPWFromEmail(model.Username, DBPW1).ToList();

I haven't done this in EF, but in SQL ADO.NET, you still create the parameter and just mark the parameter direction as Output, then after the proc runs, the parameter value is populated.

You should be able to do the same thing here.

EDIT Looks like ObjectParameter doesn't define the parameter direction. Maybe it's done automatically - I'd have to try it to see if it works.

var DPBW1 = new ObjectParameter("EncrPass", typeof(string));

EDIT It does work without setting the parameter direction