Nhibernate C# - Return only objects where string property is not null or empty

Question

I'm writing a query using ICriteria that should return only the objects where property "Message" has value (i.e. is not null or empty). Below is the format I'm using.

ICriteria.Add(Restrictions.Not(Restrictions.Eq("Message", " "));
ICriteria.Add(Restrictions.Not(Restrictions.Eq("Message", String.Empty));

Can somebody help me with this? Thank you!

taylonr · Accepted Answer · 2010-01-21 01:02:51Z

4

You might want something like:

ICriteria a = session.CreateCriteria(typeof(A));
a.add(Restrictions.Not(Restrictions.Eq("Message", " "));
a.add(Restrictions.Not(Restrictions.Eq("Message", string.Empty));

Although, your first one isn't really checking null, it's checking a single space.

answered Jan 21, 2010 at 1:02

taylonr

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o.k.w · Accepted Answer · 2010-01-21 01:33:16Z

3

I've not tried this, but it thnk the following should work:

ICriteria crit = session.CreateCriteria(typeof(theType))
                   .Add(Restrictions.IsNotNull("Message"))
                   .Add(Restrictions.IsNotEmpty("Message"));

edited Jan 21, 2010 at 1:33

answered Jan 21, 2010 at 1:05

o.k.w

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3 Comments

Amith George Over a year ago

Tried it out. It works. I guess its obvious, but the .Add() needs to be called on the ICriteria object as shown in taylonr's answer.

o.k.w Over a year ago

Oh yes, I blindly copied the original one. Haha. Ok fixed it.

jim Over a year ago

isn't IsNotEmpty meant only for collections?

alan · Accepted Answer · 2010-02-10 23:02:30Z

1

Finally, I discovered the combination I was looking for!

lvCriteria.Add(Restrictions.Not(Expression.Eq("Msg", string.Empty)));

This combination of Restrictions and Expression works as expected; narrowing out all empty strings. I do not know why I could not achieve these results earlier even with:

lvCriteria.Add(Restrictions.Not(Restrictions.Eq("Msg", string.Empty)));

Thank you to all who tried.

edited Feb 10, 2010 at 23:02

answered Jan 21, 2010 at 14:37

alan

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3 Comments

alan Over a year ago

By the way, this response is from alan. The original poster.

taylonr Over a year ago

I believe that IsNotEmpty is for collections, but I think IsNotNull is for any object (at least IsNull can be used for any object). In that case, for the empty string, you could check the length of the string.

alan Over a year ago

Any suggestions as to how to check the length of the property?

Dyadenka · Accepted Answer · 2010-04-13 15:22:03Z

1

What you really need is:

ICriteria crit = session.CreateCriteria(typeof(theType))
.Add(Restrictions.Not(Restrictions.Eq("Msg", string.Empty)))
.Add(Restrictions.IsNotNull("Msg"))

This is working fine for me and profiler shows correct SQL i.e. something like:

msg<>'' and msg is not null.

First answer did not work for me as Restrictions.IsNotEmpty/Empty applies only to collections (in NH 2.0.1 at least).

answered Apr 13, 2010 at 15:22

Dyadenka

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