What is the point of the additional_data property?

[AlexAntonides]

Hi everyone,

For quite a while now, I've been using the additional_data property to extend products and variants and to attach custom logic onto it using the API. This has been a positive experience. However, recently, I've been trying to attach additional_data using the create/update workflows and noticed that these workflows are quite limited in how they handle this data. Even simple tasks become frustrating. After digging into these workflows, I'm questioning whether I'm using additional_data correctly, and ultimately, what its intended purpose even is.

According to Medusa's documentation, additional_data should be used to link custom modules to commerce modules, for example, when creating a product,

"additional_data": {
    "brand": "Acme"
}

This works as expected through the API. However, I need to create seeds, which necessitates using workflows, and this is where the problem lies.
Examining the source code for the CreateProducts Workflow, I noticed that the additional_data is applied to all provided products, rather than allowing per-product additional_data.

When creating seeds for my new models, I found that the create/update workflows apply additional_data to all entities in the request:

"products": [
    {
        "title": "product 1",
    },
    {
        "title": "product 2",
    }
],
"additional_data": {
     "brand": "Acme",      // This brand will be linked to both product 1 and product 2
}

Therefore, to apply different branding when creating products through a seed, I have to call the createProductsWorkflow for each product,

for (const productData of products) {
    const { result: product } = await createProductsWorkflow(container).run({
        input: {
            products: [productData.data],
            additional_data: productData.additional_data
        },
    })
}

This becomes even more cumbersome when needing to pass additional_data to variants during product creation, as this is not supported in the workflow or the API route. Consequently, for each product, I must also call the CreateVariants workflow,

for (const productData of products) {
    const { variants, ...product } = productData
    const { result: productResult } = await createProductsWorkflow(container).run({
        input: {
            products: [product],
            additional_data: productData.additional_data
        },
    })  
    for (const variantData of variants) {
        const { result: variantResult } = await createVariantsWorkflow(container).run({
            input: {
                product_variants: [variantData.variant],
                additional_data: variantData.additional_data
            },
        })  
    }
}

Why can't we simply define the additional_data per product and variant directly within the createProductsWorkflow input, like this,

const { result: products } = await createProductsWorkflow(container).run({
    input: {
        products: [ 
              {
                  title: "product 1",
                  variants: {
                        title: "variant 1",
                        additional_data: {
                              data: "example",
                        },
                  },
                  additional_data: {
                      brand: "Acme",
                  }
              },
              {
                  title: "product 2",
                  variants: {
                        title: "variant 2",
                        additional_data: {
                              data: "another example",
                        },
                  },
                  additional_data: {
                      brand: "different brand",
                  }
              }
        ] 
    },
})