get last in LINQ list

Question

``` Context db = new Context(); List invoice = (from LocalInvoice in db.Invoices where LocalInvoice.Site_Id == this.SiteIdentifier select LocalInvoice).ToList(); ``` Returns a list of records. I want to select the last in the list. I've tried `.ToList().LastOrDefault();` but the error im getting is cannot convert type 'invoice' to 'System.Collections.Generic.List. Why is it saying this have I not declared invoice as a list `List invoice` Any help much appreciated. Ta EDIT Thanks for the reply everyone i've tried what you all have advised and each time im getting the error: The query operator 'LastOrDefault' is not supported. Also I havent actually explained what I am trying to do overall which may be causing a problem. I have a table containing all the invoices, each with a seperate 'id'. However each record will have a SiteIdentifier column which is used multiple times for different invoices. So each Site may have multiple invoices. Trying to get the most recent Inv…

Accepted Answer

LastOrDefault will return a single element. You shouldn't call ToList without applying a filter first, it would retrieve all the rows from the database while you just need one.

```
var invoice = db.Invoices.LastOrDefault(s => s.Site_Id == this.SiteIdentifier);
```

Also you have to apply ordering if you are querying a relational table. LastOrDefault is only meaningful with in-memory collections. Looks like it is not supported in EF and will throw an exception.

Best solution is to inverse the ordering and use FirstOrDefault method:

```
var invoice = db.Invoices.OrderByDescending(s => s.Id) 
                         .FirstOrDefault(s => s.Site_Id == this.SiteIdentifier);
```

get last in LINQ list

Solution

Problem