Entity Framework - Code First - Foreign Key Constraint

Question

I am developing a database using a code-first approach with entity framework.

I want to use foreign keys between a few tables, for instance:

 public class Producer
    {

        [Key]
        public int Id { get; set; }

        [Required]
        [StringLength(254)]
        public string Name { get; set; }
    }

then another files model is simplified as

 public class Product
    {

        [Key]
        public int Id { get; set; }

        [Required]
        [StringLength(254)]
        public string Name { get; set; }
    }

What i want is to define a ProducerId field on the Product and have it link to the Producers ID field, but i cant tell how to tell it what model/table its linking to.

Can anyone clarify? I think based on what ive read it may seem like i need to make the ID fields more descriptive and EF will find the field, is ProductId for the Products Id field - but im still not positive it will work across the tables.

Is that correct or have i missed something?

Edit:

I tried the first answer below, but using more tables than just the two, and got this error:

fail: Microsoft.EntityFrameworkCore.Database.Command[20102]
      Failed executing DbCommand (46ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      CREATE TABLE `Product` (
          `ProductId` int NOT NULL AUTO_INCREMENT,
          `ProducerId` int NOT NULL,
          `ProductCategoryId` int NOT NULL,
          `ProductStyleId` int NOT NULL,
          `Name` varchar(254) NULL,
          `Year` datetime NOT NULL,
          `CreatedAt` datetime NOT NULL,
          `CategoryId` int NOT NULL,
          `StyleId` int NOT NULL,
          `Image` varbinary(4000) NULL,
          `TastingNotes` text NULL,
          `Description` text NULL,
          PRIMARY KEY (`ProductId`),
          CONSTRAINT `FK_Product_Producers_ProducerId` FOREIGN KEY (`ProducerId`) REFERENCES `Producers` (`ProducerId`) ON DELETE CASCADE,
          CONSTRAINT `FK_Product_ProductCategory_ProductCategoryId` FOREIGN KEY (`ProductCategoryId`) REFERENCES `ProductCategory` (`ProductCategoryId`) ON DELETE CASCADE,
          CONSTRAINT `FK_Product_ProductStyle_ProductStyleId` FOREIGN KEY (`ProductStyleId`) REFERENCES `ProductStyle` (`ProductStyleId`) ON DELETE CASCADE
      );
Failed executing DbCommand (46ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
CREATE TABLE `Product` (
    `ProductId` int NOT NULL AUTO_INCREMENT,
    `ProducerId` int NOT NULL,
    `ProductCategoryId` int NOT NULL,
    `ProductStyleId` int NOT NULL,
    `Name` varchar(254) NULL,
    `Year` datetime NOT NULL,
    `CreatedAt` datetime NOT NULL,
    `CategoryId` int NOT NULL,
    `StyleId` int NOT NULL,
    `Image` varbinary(4000) NULL,
    `TastingNotes` text NULL,
    `Description` text NULL,
    PRIMARY KEY (`ProductId`),
    CONSTRAINT `FK_Product_Producers_ProducerId` FOREIGN KEY (`ProducerId`) REFERENCES `Producers` (`ProducerId`) ON DELETE CASCADE,
    CONSTRAINT `FK_Product_ProductCategory_ProductCategoryId` FOREIGN KEY (`ProductCategoryId`) REFERENCES `ProductCategory` (`ProductCategoryId`) ON DELETE CASCADE,
    CONSTRAINT `FK_Product_ProductStyle_ProductStyleId` FOREIGN KEY (`ProductStyleId`) REFERENCES `ProductStyle` (`ProductStyleId`) ON DELETE CASCADE
);
MySql.Data.MySqlClient.MySqlException (0x80004005): Cannot add foreign key constraint
   at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
   at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int64& insertedId)
   at MySql.Data.MySqlClient.Driver.GetResult(Int32 statementId, Int32& affectedRows, Int64& insertedId)
   at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
   at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader()
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1 migrationCommands, IRelationalConnection connection)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
C

Answer 1

To add a foreign key just add this on the Product class add:

public int ProducerId { get; set; }

[ForeignKey("ProducerId")]  //This attribute is optional bc EF should recognize Product obj specifi

public virtual Producer Producer { get; set; }

By adding public virtual Producer Producer EF Core should recognize the ProducerId property as a foreign key. virtual is used to enable Lazy Loading if you like.

The [ForeignKey()] is an optional attribute to explicitly point to the foreign and navigation keys. This post should further explain the optional use of [ForeignKey()]. How Should I Declare Foreign Key Relationships Using Code First Entity Framework (4.1) in MVC3?

To be clear, to simply add a foreign key, all that is required is adding this to class:

public int ProducerId { get; set; }
public virtual Producer Producer { get; set; }