CODEWITHSUNDEEP
c#sqlsql-serverasp.net-mvcentity-framework-migrations
T D Nguyen
T D Nguyen

Reputation: 7613

Remove a table column using code first ASP MVC

I have two class A and B. B has a foreign key to A. 

class A {
     byte Id{get; set;}
     string Name{get;set;}
 }

and 

class B {
     byte Id{get; set;}
     string Name{get;set;}
     A A{get;set;}
     byte AId{get;set;}
 }

My problem is:

  1. I created a class A with a property id of type int
  2. I run update-database
  3. I modified data type of id to byte
  4. I run update-database again
  5. I found that in table B that use id of A as the foreign key has two columns, i.e., aId and a_Id.

My question is: how can I remove the column a_Id using code first approach? Or anyway that is feasible.

I tried to run the query: ALTER TABLE DROP COLUMN a_Id - failed because one or more objects access this column.

I also tried to delete the column directly using VS Server explorer, remove the column by using table definition. But it did not work too.

Thanks

Upvotes: 2

Views: 4143

Answers (4)

Marah Eissa
Marah Eissa

Reputation: 1

I faced the same problem while I was learning ASP.net the solution to delete the unwanted prop is the following:

1- you have to delete it as an index so add new migration and write this instruction in the UP method

    DropIndex("dbo.TableName", new[] { "ColumnName" });

2- update-database note: at this phase you can make sure that the index has gone if you open the definition of the table (SQL code)

3- New migration but now write in the Up method

 DropColumn("TableName", "ColumnName");

4- Update-database

and it's gone

Upvotes: 0

Mehran Ahmadifar
Mehran Ahmadifar

Reputation: 1

You Can Comment B class and Update-database! (drop table) again update-database with B class! :) for me this work!

Upvotes: 0

marto
marto

Reputation: 460

Perhaps you forgot to change B's FK type in the model.

[Required]
public byte ClassAId{ get; set; }

public virtual ClassA ClassA{ get; set; }

Also check out what you have in your migration's Up and Down methods.

Attribute [Key] over classA's Id could also be useful.

Upvotes: 0

Ahmad Farhan
Ahmad Farhan

Reputation: 605

Just follow these steps
1: Remove properties from the model.
2: Run 'Enable-Migrations' in package manage console.
3: Next Run 'Add-Migration "MigrationsName"'. if any case it is showing 'The project tesproject failed to build then build project again.
4: Now run 'Update-Database'

Upvotes: 1

Related Questions