Dynamically Instantiate Model object in Entity Framework DB first by passing type as parameter

asp.net c# entity-framework entity-framework-6 linq

Question

Have a requirement to create instance of Entity Framework generated Model class dynamically by passing table name as parameter (Model generated in DB first approach and using EF 6.0)

like,

// Input Param
string tableName 

// Context always same
DBContext dbContext= new DBContext(); 

//Need to create object query dynamically by passing 
//table name from front end as below  

 IQueryable<"tableName"> query = dbContext."tableName ";

Need to pass 100+ tables as input param and structure of all table is same.

Please help.

1
4
5/24/2017 1:00:44 PM

Accepted Answer

You can use a Dictionary. Maybe you want something like this:

// Input Param
string tableName = "TblStudents";
Dictionary<string, Type> myDictionary = new Dictionary<string, Type>()
{
    { "TblStudents", typeof(TblStudent) },
    { "TblTeachers", typeof(TblTeacher) }
};

// Context always same
DBContext dbContext = new DBContext();
DbSet dbSet = dbContext.Set(myDictionary[tableName]);

But you can not use none of the LINQ extension methods because they are defined on the generic type IQueryable<T> but the non-generic overload of DbContext.Set, returns a non-generic DbSet. Also this class implements non generic IQueryable. You have two option to use LINQ methods here:

  1. Add System.Linq.Dynamic to your project (to install System.Linq.Dynamic, run the following command in the Package Manager Console ):

    Install-Package System.Linq.Dynamic

    And then you can:

    var dbSet = dbContext.Set(myDictionary[tableName]).Where("Id = @a", 12);
    
  2. Use the Find method:

    //But this returns a single instance of your type
    var dbSet = dbContext.Set(myDictionary[tableName]).Find(12);
    
7
9/29/2017 2:28:17 PM


Related Questions





Related

Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow