Doctrine: Mapped key being inserted as NULL

Question

I have 2 tables, cart and product_inventory mapped by the column sku. product_inventory has sku as primary key instead of id.

Mapping is as follows:

AppBundle\Entity\Cart:
    type: entity
    table: cart
    repositoryClass: AppBundle\Repository\CartRepository
    manyToOne:
      variant:
        targetEntity: ProductInventory
        inversedBy: cart
        joinColumn:
          name: sku
          referencedColumnName: sku
    id:
        id:
            type: integer
            nullable: false
            options:
                unsigned: true
            id: true
            generator:
                strategy: IDENTITY
    fields:
        userId:
            type: integer
            nullable: false
            options:
                unsigned: false
            column: user_id
        sku:
            type: string
            nullable: false
            length: 10
            options:
                fixed: false
        quantity:
            type: tinyint
            nullable: false
    lifecycleCallbacks: {  }

AppBundle\Entity\ProductInventory:
    type: entity
    table: product_inventory
    repositoryClass: AppBundle\Repository\ProductInventoryRepository
    manyToOne:
        product:
          targetEntity: Product
          inversedBy: inventory
          joinColumn:
              name: product_id
              referencedColumnName: id
    oneToMany:
        attribute_value:
          targetEntity: ProductAttributeValue
          mappedBy: inventory
          cascade: [persist]
        cart:
          targetEntity: Cart
          mappedBy: variant
    id:
        sku:
            type: string
            nullable: false
            length: 10
            options:
                fixed: false
            id: true
            generator:
                strategy: IDENTITY
    fields:
        productId:
            type: integer
            nullable: false
            options:
                unsigned: true
            column: product_id
        quantityAvailable:
            type: tinyint
            nullable: false
            column: quantity_available
        quantitySold:
            type: smallint
            nullable: false
            options:
                unsigned: true
            column: quantity_sold
    lifecycleCallbacks: {  }

I'm trying to insert a record into the cart table but the mapped key sku is inserted as NULL. I've tried changing the primary key to the default value id, but it didn't work. I'm not able to figure out the issue.

Any help is greatly appreciated.

Answer 1

The mapping was not correct. It should have been the other way around. A cart can have many products (oneToMany) and there can be many products in a cart (manyToOne).

AppBundle\Entity\Cart:
    type: entity
    table: cart
    repositoryClass: AppBundle\Repository\CartRepository
    oneToMany:
        inventory:
          targetEntity: ProductInventory
          mappedBy: cart

AppBundle\Entity\ProductInventory:
    type: entity
    table: product_inventory
    repositoryClass: AppBundle\Repository\ProductInventoryRepository
    manyToOne:
      cart:
          targetEntity: Cart
          inversedBy: inventory
          joinColumn:
            name: sku
            referencedColumnName: sku

I thank you all for taking the time to help me out.

Answer 2

Your definition of the sku field is a string and your generator is defined to use IDENTITY generator strategy which depending if using mysql will be translated to AUTO_INCREMENTcolumn attribute for the sku. Check the doctrine reference for the strategies types.