Refactor this Lambda Expression

Question

I need to refactor this code so that the data service wont query two workTypes per row item. Thanks in advance.

 _attributeGroups = attributeGroups.Select(attributeGroupRowModel =>
 new AttributeGroupRowModel()
 {
 Name = attributeGroupRowModel.Name, 
 WorkType = workTypes.First(wt => wt.Id == attributeGroupRowModel.WorkTypeId).Description,
 IsExpired = workTypes.First(wt => wt.Id == attributeGroupRowModel.WorkTypeId).IsExpired, //todo: not efficient, to be refactored
 }).ToList();

Answer 1

_attributeGroups = attributeGroups.Select(attributeGroupRowModel => 
{
 var wt = workTypes.First(x => x.Id == attributeGroupRowModel.WorkTypeId);
 return new AttributeGroupRowModel()
 {
 Name = attributeGroupRowModel.Name, 
 WorkType = wt.Description,
 IsExpired = wt.IsExpired,
 };
}).ToList();

or if you prefer LINQ:

_attributeGroups = 
 (from attributeGroupRowModel in attributeGroups
 let wt = workTypes.First(x => x.Id == attributeGroupRowModel.WorkTypeId)
 select new AttributeGroupRowModel()
 {
 Name = attributeGroupRowModel.Name, 
 WorkType = wt.Description,
 IsExpired = wt.IsExpired,
 }).ToList();

• lincx: I actually tried the first one before I posted here, I just realized that my error is the same as yours, the freaking semi colon after return lol :)
• lincx: actually the first one i saw has no semicolon on the return (or it just been delayed because you were too fast), anyway thanks man;)

Answer 2

You can use a statement lambda instead of an expression lambda. A statement lambda allows you, among other things, to define variables:

_attributeGroups = attributeGroups.Select(attributeGroupRowModel => 
{
 var w = workTypes.First(wt => wt.Id == attributeGroupRowModel.WorkTypeId);
 return new AttributeGroupRowModel()
 {
 Name = attributeGroupRowModel.Name, 
 WorkType = w.Description,
 IsExpired = w.IsExpired,
 };
}).ToList();