Panic while retrieving inner associations via pointer based outer association

arrowak commented 4 years ago

Description

The application panics when trying to eager load multi-level associations.

Steps to Reproduce the Problem

I have below model structure in my application.

organisation.go

type Organisation struct {
    ID            uuid.UUID `json:"id" db:"id"`
    Name          string    `json:"name" db:"name"`
    CreatedAt     time.Time `json:"created_at" db:"created_at"`
    UpdatedAt     time.Time `json:"updated_at" db:"updated_at"`

    Applications *Applications `json:"applications" has_many:"applications" db:"-"`
}

application.go

type Application struct {
    ID                uuid.UUID `json:"id" db:"id"`
    Name              string    `json:"name" db:"name"`
    ApplicationtypeID uuid.UUID `json:"applicationtype_id" db:"applicationtype_id"`
    OrganisationID    uuid.UUID `json:"organisation_id" db:"organisation_id"`
    CreatedAt         time.Time `json:"created_at" db:"created_at"`
    UpdatedAt         time.Time `json:"updated_at" db:"updated_at"`

    Organisation    *Organisation   `json:"organisation" belongs_to:"organisation" db:"-" `
    Applicationtype *Applicationtype `json:"applicationtype" belongs_to:"applicationtype" db:"-"`
}

applicationtype.go

type Applicationtype struct {
    ID        uuid.UUID `json:"id" db:"id"`
    Name      string    `json:"name" db:"name"`
    CreatedAt time.Time `json:"created_at" db:"created_at"`
    UpdatedAt time.Time `json:"updated_at" db:"updated_at"`
}

In the Show action of organisations.go, I am doing trying to eager load all the Applications for the current Organisation and also go another level deeper by eager loading Applicationtype for every Application found.

if err := tx.Eager("Applications.Applicationtype").Find(organisation, c.Param("organisation_id")); err != nil {
    return c.Error(http.StatusNotFound, err)
}

Expected Behavior

The statement should return -

All the details of the Organisation
All the details of all the Applications that belong to this Organisation
Applicationtype of each Application that was found in above step

Actual Behavior

It succeeds in getting the details of the Organisation
It succeeds in getting the details of all the Applications belonging to this Organisation
But fails to get Applicationtype for the above Applications, with following error -
```
could not retrieve associations: could not get struct associations: not a struct
```

The statement succeeds when I convert

Applications *Applications `json:"applications" has_many:"applications" db:"-"`

to

Applications Applications `json:"applications" has_many:"applications" db:"-"`

Info

OS: macOS Catalina v10.15.5 pop Version: 5.2.3 via Buffalo v0.16.10

monfresh commented 4 years ago

I'm seeing the same error in an application I'm working on. It's the exact same situation. We are trying to eager load "OriginDutyStation.Address" where OriginDutyStation is a pointer in the model.

arrowak commented 4 years ago

Anything here people? For a large struct, It is not making sense to work on a copy rather than a pointer.

It would really help if you take a look into this.

gobuffalo / pop