Creating a generic class method update on Cassandra db - linq

Question

Examining the documentation at datastax on the cassandra c# driver (cassandra C# driver documentation), the following code is presented:
// Update
users.Where(u => u.UserId == "john")
.Select(u => new User { LastAccess = TimeUuid.NewId()})
.Update()
.Execute();
I decided to create a repository like this:
public bool Update(Func<T,bool> whereExpression,Func<T,T> selectExpression)
{
try
{
this.AllRecords
.Where(whereExpression)
.Select(selectExpression)
.Update()
.Execute();
}
catch (Exception)
{
throw;
}
}
I received the following error:
Error 1 'System.Collections.Generic.IEnumerable' does not contain a definition for 'Update' and no extension method 'Update' accepting a first argument of type 'System.Collections.Generic.IEnumerable' could be found (are you missing a using directive or an assembly reference?)
I have imported all the necssary namespaces
using System.Linq;
using Cassandra.Data.Linq;

Answer 1

The problem lies with the construction of your method parameters. If you inspect the Cassandra.Data.Linq namespace, the Where extension method is presented as:
public static CqlQuery<TSource> Where<TSource>(this CqlQuery<TSource> source, Expression<Func<TSource, bool>> predicate);
Hence, you should update your code as:
public bool Update(Expression<Func<T,bool>> whereExpression, Expression<Func<T,T>> selectExpression)
{
try
{
this.AllRecords
.Where(whereExpression)
.Select(selectExpression)
.Update()
.Execute();
}
catch (Exception)
{
throw;
}
}
Also, don't forget to import the following namespace for this to work:
using System.Linq;
using System.Linq.Expressions;
using Cassandra.Data.Linq;
That's all that you need to do to get this working...