Multi-tenancy logic related to repository, usecase or handler layer?

@eminetto thanks for your amazing work! Go is just a hobby for me and I'm having fun. I'm learning a lot from your project.

I'm trying to understand if multi-tenancy column/table based is something to be "included", if it is "related to" the repository, service or handler level.

Example

Adding tenant.go model like this:

package entity

type Tenant struct {
    ID   int64  `json:"id"`
    Name string `json:"name"`
}

to other models like this:

package entity

import "time"

type Bookmark struct {
    ID          ID        `json:"id"`
    TenantID    int64     `json:"tenant_id"` // <--- here
    Tenant      *Tenant   // <--- here
    Name        string    `json:"name"`
    Description string    `json:"description"`
    Link        string    `json:"link"`
    Tags        []string  `json:"tags"`
    Favorite    bool      `json:"favorite"`
    CreatedAt   time.Time `json:"created_at"`
}

Let's talk for example of the Store() method:

from the delivery (handler/bookmark.go) I call service.Store()
in Bookmark Service Store() I call repo.Store()
in Bookmark Repository (Mongo or InMemory) Store() I save the bookmark object.

Question

Let's say my tenant_id is a field of a User struct in context on every request (authenticated by a third party middleware).

Where do you think I should do something like below? In handler, service or repository?

tenantID := GetTenantIDFromUserInContext()
article.TenantID = tenantID

Doubts about fetch queries

Today, before I discover the amazing "clean architecture", I'm using a where clause in my SQL queries (https://github.com/go-pg/pg/issues/1179), like this:

// Used as: "q.Apply(FilterByTenant(ctx))"
func FilterByTenant(ctx context.Context) func(q *orm.Query) (*orm.Query, error) {
    user := ctx.Value(auth.CTXKeyUser).(*models.User)
    return func(q *orm.Query) (*orm.Query, error) {
        q = q.Where("tenant_id = ?", user.TenantID)
        return q, nil
    }
}

I think maybe the concept of FilterByTenant in the service layer is an unnecessary repetition and should belong to lower levels like repositories?

But I also think that the main multi-tenancy logic does not change with the change of possible repository types (Postgres, Mysql, Mongo, microservices).

What do you think about it?

eminetto / clean-architecture-go