LINQ to Entities does not recognize the method 'Int32 Min(Int32, Int32)'? - linq

Question

Im getting this error when I execute the following code, any Ideas how to fix it?
LINQ to Entities does not recognize the method 'Int32 Min(Int32, Int32)' method, and this method cannot be translated into a store expression.
result = items.ToList()
.Select(b => new BatchToWorkOnModel()
{
BatchID = b.Batch.ID,
SummaryNotes = b.Batch.Notes,
RowVersion = b.Batch.RowVersion,
Items = items
.Select(i => new ItemToWorkOnModel()
{
SupplierTitle = i.Title,
ItemID = i.ID,
BatchID = i.BatchID ?? 0,
ItemDate = i.PubDate,
// KB - Issue 276 - Return the correct Outlet name for each item
Outlet = i.Items_SupplierFields != null ? i.Items_SupplierFields.SupplierMediaChannel != null ? i.Items_SupplierFields.SupplierMediaChannel.Name : null : null,
Status = ((short)ItemStatus.Complete == i.StatusID ? "Done" : "Not done"),
NumberInBatch = i.NumInBatch,
Text = string.IsNullOrEmpty(i.Body) ? "" : i.Body.Substring(0, Math.Min(i.Body.Length, 50)) + (i.Body.Length < 50 ? "" : "..."),
IsRelevant = i.IsRelevant == 1,
PreviouslyCompleted = i.PreviouslyCompleted > 0 ? true : false
}).ToList()
})
.FirstOrDefault();

Answer 1

It seems Math.Min is not implemented by the EF query provider. You should be able to fix it by simply applying AsEnumerable on your items collection to do the expression using Linq to Objects instead;
Items = items.AsEnumerable().Select(i => new ItemToWorkOnModel()...
If you add a where condition to the item selection (seems a little strange to take all items in the whole table), you'll want to add it before AsEnumerable() to allow EF to do the filtering in the database.
Also, you only want the first result from the query, but you're fetching all of them using ToList() before cutting the list down to a single item. You may want to remove the ToList() so that EF/the underlying database can return only a single result;
result = items.Select(b => new BatchToWorkOnModel()...

Answer 2

You do not need Math.Min.
The line in question is:
Text = string.IsNullOrEmpty(i.Body)
? "" : i.Body.Substring(0, Math.Min(i.Body.Length, 50)) + (i.Body.Length < 50 ? "" : "...")
So what does this line return?
If i.Body is null or empty it returns an empty string. If it is 50 or more characters long it returns a substring of 50 characters and appends "...".
If the length is less than 50 it takes a substring with the length of the string and appends an empty string. But that's just the original string.
Text = string.IsNullOrEmpty(i.Body)
? "" : (i.Body.Length < 50 ? i.Body : i.Body.Substring(0, 50) + "...")