CODEWITHSUNDEEP
structinterfacego
bodokaiser
bodokaiser

Reputation: 15752

How to work around "type interface has no field or method" error?

I want to write an abstraction to the mgo API:

package manager

import "labix.org/v2/mgo"

type Manager struct {
    collection *mgo.Collection
}

func (m *Manager) Update(model interface{}) error {
    return m.collection.UpdateId(model.Id, model)
}

When compiling I get "model.Id undefined (interface{} has no field or method Id)" which itself is obvious.

Is this a totally wrong approach from my side or is there an easy workaround how to let the compiler "trust" that there will be an Id property on runtime on passed structs.

Upvotes: 4

Views: 5486

Answers (1)

VonC
VonC

Reputation: 1328522

You could defined an interface which declares an Id function

type Ider interface {
    Id() interface{}
}

If your model is an Ider, then your function will work.

func (m *Manager) Update(model Ider) error {

Considering the mgo#Collection.UpdateId() function takes interface{}, it will accept an Ider.

Upvotes: 4

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