Dynamic query using LINQ to SQL

Question

I need to figure out if it is possible to dynamically build a query with LINQ, dynamically selecting the table in which to perform the query.

This is an example of w

Answer 1

I've found a way to do it, but I'm not sure if I'd use this code. If you have a DataContext that contains two tables:

PrimaryTable 
    ID,
    FirstValue,
    SecondValue

SecondaryTable
    ID,
    FirstSecondaryValue

You could use the following DataHelper class:

class DataHelper
{
    public MyDatabaseDataContext db = new MyDatabaseDataContext();

    List GetDynamicList() where T : class
    {
        System.Data.Linq.Table table = db.GetTable();

        var result = from a in table select a;

        return result.ToList();
    }

    public List GetWhatIWant(string tableName)
    {
        Type myClass = Type.GetType("DynamicLinqToSql." + tableName);
        MethodInfo method = typeof(DataHelper).GetMethod("GetDynamicList", BindingFlags.NonPublic | BindingFlags.Instance);
        method = method.MakeGenericMethod(myClass);
        return (List)method.Invoke(this, null);
    }
}

Then you can create an instance of your DataHelper and call the GetWhatIWant method, passing in the table name.

var dataHelper = new DataHelper();

List myFirstList = dataHelper.GetWhatIWant("PrimaryTable");

for (int i = 0; i < 5 && i < myFirstList.Count; i++)
{
    System.Console.WriteLine(String.Format("{0} - {1}", myFirstList[i].FirstValue.ToString(),  myFirstList[i].SecondValue.ToString()));
}

List mySecondList = dataHelper.GetWhatIWant("SecondaryTable");

for (int i = 0; i < 5 && i < mySecondList.Count; i++)
{
    System.Console.WriteLine(mySecondList[i].FirstSecondaryValue.ToString());
}

System.Console.ReadKey();