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c#entity-frameworklinq
Nayan Soni
Nayan Soni

Reputation: 1041

Convert table name (in string) to use it in the LINQ query : C#, Entity Framework

I have a list of table names in form of strings. I want to loop through the list and use the table name in the LINQ query:

var db = new SomeContext();

// for a single table I can use the LINQ query as
var res = from q in db.Table
          where ......
          select q;

and it works just fine.

The above approach is hard coding. I need a generic solution for this to loop through multiple tables whose names are stored in a list.

// list of string containing table names
List<stringtableNames = [Get the table list from some source]
// not a problem here

loop through the table names and for each name execute a LINQ query as shown below

foreach(string table in tableNames)
{ 
    var queryRes = from t in table
                   where <some_condition>
                   select t; 
}

In the above statements "from t in table" above is not valid as "table" is a string. I need actual table object reference to use.

Need help on how do I go about doing that.

Upvotes: 0

Views: 2756

Answers (3)

mnieto
mnieto

Reputation: 3874

You can use the DbContext.Set method:

Set(System.Type.GetType("TableName"))

Above sentence will return a non generic DbSet. So, you will not be able to query with linq as usual. But you can use dynamic linq. ScottGu will explain it better than me. Please, check this thread for other solutions.

Upvotes: 1

blogprogramisty.net
blogprogramisty.net

Reputation: 1782

select, where, from is one way to define LINQ but You can use it if you have a list of elements (IEnumerable<T> for example), but You have only name of Your table

I think You have to create a regular SQL query 

foreach(string table in tableNames)
{ 
  var query =$"select * from  {table} where <some_condition>"; 
  var list = db.ExecuteStoreQuery<Obj>(query);
}

In EF You can execute regular query

Upvotes: 0

rdn87
rdn87

Reputation: 724

In EF you can execute SQL Code.

In this example i use EF with SQL (String)

var db = new SomeContext();
var list = db.ExecuteStoreQuery<Obj>(Obj.sql);



class Obj
{
   public const string sql = @"select [tbl].[field] from [tbl]";
}

Upvotes: 0

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