Mysql – Repository Pattern without LINQ or other ORM

.netmonomysqlrepository

Does it makes sense to use the Repository pattern without the use of LINQ or some other ORM? I am writing an application in MONO and using MySQL, was thinking of using the repositoy pattern but not going to be able to deal with IQueryable. I was thinking of just exposing more methods on the repository to make it obvious that filtering was going to happen on the db side with the repository call. Any suggestions if that is a valid use of the design or any other design ideas instead?

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Repository has nothing at all to do with IQueryable. What you are thinking of is the Rob Conory .net 3.5 take on the repository pattern, which is actually more of a data broker pattern.

A repository is responsible for returning objects, and deals with data access so that the rest of your application can remain ignorant of it.

You can see a very high level description on Martin Fowlers site

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.net – Entity Framework vs LINQ to SQL

LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It's a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5.

LINQ to Entities (ADO.Net Entity Framework) is an ORM (Object Relational Mapper) API which allows for a broad definition of object domain models and their relationships to many different ADO.Net data providers. As such, you can mix and match a number of different database vendors, application servers or protocols to design an aggregated mash-up of objects which are constructed from a variety of tables, sources, services, etc. ADO.Net Framework was released with the .Net Framework 3.5 SP1.

This is a good introductory article on MSDN: Introducing LINQ to Relational Data

C# – LINQ query on a DataTable

You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable. Like so:

var results = from myRow in myDataTable.AsEnumerable()
where myRow.Field<int>("RowNo") == 1
select myRow;

And as @Keith says, you'll need to add a reference to System.Data.DataSetExtensions

AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the CopyToDataTable() extension.

Below is query with Lambda Expression,

var result = myDataTable
    .AsEnumerable()
    .Where(myRow => myRow.Field<int>("RowNo") == 1);

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C# – LINQ query on a DataTable

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