Question

Do you have an idea how to write the following code nicer/shorter 🙂
I need to check if the field form form is not empty and then add
criterion to the query,
thanks 🙂

AbstractCriterion restrictions = null; 

if (model.DateFrom != null) 
  AddRestriction(ref restrictions, 
   Restrictions.Ge(Projections.Property<Invoice>(x => x.DateIn), model.DateForm)); 

if (model.DateTo != null) 
  AddRestriction(ref restrictions, 
    Restrictions.Le(Projections.Property<Invoice>(x => x.DateIn), model.DateTo)); 

if (!string.IsNullOrEmpty(model.Prop1)) 
   AddRestriction(ref restrictions, 
     Restrictions.Eq(Projections.Property<Invoice>(x => x.Prop1), model.Prop1)); 

// ... many more conditions :) 

return m_session.QueryOver<Invoice>().Where(restrictions).List();

Answer 1

You don’t need the ref keyword for starters. I think this is nicer without sacrificing readability:

var query = session.QueryOver<Invoice>();

Action<object, ICriterion> addIfNonNull = (o, c) =>
                                            {
                                                if (o != null)
                                                {
                                                    query.And(c);
                                                }
                                            };

addIfNonNull(model.Prop1, Restrictions.Eq(Projections.Property<Invoice>(x => x.Prop1), model.Prop1));

etc.