Remove a table column using code first ASP MVC

Question

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:

I created a class A with a property id of type int
I run update-database
I modified data type of id to byte
I run update-database again
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

Should you provide A, B class source code? "text" question will get back text answer — Dan Nguyen
– Dan Nguyen, Commented Apr 29, 2017 at 9:20

Ahmad Farhan · Accepted Answer · 2017-04-29 09:10:33Z

1

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'

answered Apr 29, 2017 at 9:10

Ahmad Farhan

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2 Comments

T D Nguyen Over a year ago

What do you mean by remove properties from the model? Remove A related properties from B, e.g., id??

Ahmad Farhan Over a year ago

The property that you are trying to remove from database table

marto · Accepted Answer · 2017-04-29 09:25:59Z

0

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.

answered Apr 29, 2017 at 9:25

marto

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Comments

Mehran Ahmadifar · Accepted Answer · 2017-04-29 09:31:22Z

0

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

answered Apr 29, 2017 at 9:31

Mehran Ahmadifar

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Comments

Marah Eissa · Accepted Answer · 2019-04-19 15:37:31Z

0

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

answered Apr 19, 2019 at 15:37

Marah Eissa

1

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