How to specify a composite primary key using EFCore Code First Migrations

Question

I'm using Asp.Net Core 2.1, Mvc, c#, EF Core with Code First and Migrations.

I'm trying to build a table that has a composite primary key in the Migration.Up() method:

migrationBuilder.CreateTable( name: "TagValueAttributes", columns: table => new { TagValueID = table.Column<Int64>(nullable: false), Identifier = table.Column<string>(nullable: false, unicode: true, maxLength: 256), Value = table.Column<string>(nullable: true, unicode: true, maxLength: 2048) }, constraints: table => { table.PrimaryKey( name: "PK_TagValueAttributes", columns: // what goes here??? ) } );

I don't know what to specify for the columns parameter of the constraints table.PrimaryKey() call. I would like columns TagValueID, and Identifier to form the composite key.

What do I need to specify for the columns parameter?

LordDraagon · Accepted Answer · 2020-11-11 09:11:27Z

32

Why do you want to put this in the Migration.Up() method ?

You can do this via the Fluent API in your DbContext by overriding OnModelCreating() method :

protected override void OnModelCreating(ModelBuilder builder) { builder.Entity<TagValueAttributes>().HasKey(t => new { t.TagValueID, t.Identifier }); }

If you want tho keep this in Migration.Up() then do:

table.PrimaryKey( name: "PK_TagValueAttributes", columns: t => new { t.Identifier, t.TagValueID } );

edited Nov 11, 2020 at 9:11

LordDraagon

60114 silver badges34 bronze badges

answered Aug 23, 2018 at 20:45

Selmir

1,2261 gold badge12 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Sam Axe Over a year ago

Thanks for your comments. However, there does not appear to be a property of table called TagValueID not one called Identifier.

Sam Axe Over a year ago

I want this in Migration.Up() because I'm using migrations. If I put it in DbContext.OnModelCreating() then I don't get to use Migrations.

Selmir Over a year ago

Mmmmh okay I removed this part of the answer, I'll be back to you in minutes with a solution I hope.

Sam Axe Over a year ago

You were very close. I'm going to fix your answer and accept it.

Selmir Over a year ago

Found the solution on my side a few seconds ago. Glad your problem was solved have a nice day.

Mark Davich · Accepted Answer · 2023-03-31 17:33:15Z

13

Using EF Core 7.0 you can use data annotations
https://learn.microsoft.com/en-us/ef/core/modeling/keys?tabs=data-annotations

using Microsoft.EntityFrameworkCore; [PrimaryKey(nameof(Identifier), nameof(TagValueID))] internal class table { public Int64 Identifier { get; set; } public string TagValueID { get; set; } public string Value { get; set; } }

edited Mar 31, 2023 at 17:33

answered Dec 28, 2022 at 21:59

Mark Davich

6381 gold badge6 silver badges23 bronze badges

3 Comments

Zin Min Over a year ago

PrimaryKey is under which name space? PrimaryKeyAttribute could not be found error is throwing even using System.ComponentModel.DataAnnotations and System.ComponentModel.DataAnnotations.Schema

Mark Davich Over a year ago

@ZinMin, the only namespace I am using is Microsoft.EntityFrameworkCore. Again, Microsoft introduced the PrimaryKey attribute in EF Core 7.0 (learn.microsoft.com/en-us/ef/core/modeling/…)

Byte Over a year ago

@ZinMin Took me a moment time to find it, but you have to install the Microsoft.EntityFrameworkCore.Abstractions package to use it.

Collectives™ on Stack Overflow

How to specify a composite primary key using EFCore Code First Migrations

2 Answers 2

5 Comments

3 Comments

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

3 Comments

Related