mongoose-external-ref v1.0.0

Mongoose External Ref

Installation

npm install mongoose-external-ref

Usage

Plugin is applied to any field of a model that is a ref and which has been provided with the field strictForeignRef.

const bandSchema = new Schema({
  lead: {type: Schema.Types.ObjectId, ref: 'User', strictForeignRef: true},
  members: [{type: Schema.Types.ObjectId, ref: 'User', strictForeignRef: true}]
});

Option 1: ref as String

The plugin should have visibility over all mongoose models loaded. So its setup must be something like:

mongoose.plugin((schema) => { 
  mongooseExternalRef.call(this, schema, mongoose.models) }
);

Of course the previous is the general case where plugin is GLOBALLY applie, check here, similarly it can be applied at model-level.

Option 2: ref as Model

The minimal reference would work ONLY IF reference in Schema is by Model (and not by String):

mongoose.plugin(mongooseExternalRef)

and Schema is like:

const User = mongoose.model('User', new Schema({
  role: String
}) );

const bandSchema = new Schema({
  lead: {type: Schema.Types.ObjectId, ref: User, strictForeignRef: true},
  ...
});

If ref property in lead property would be expressed as String ('User'), the previous would not have worked and Option 2 would be the only possibility.

Reasons behind

Unlikely it may appear, the idea behind this plugin is not to reproduce SQL "Foreign Keys" concept of RDBMSs, which is a nosense in NoSql environments. However mongoose allows to introduce soft references by using ObjectIds properties related to other models. The plugin is aiming to make these references less soft by informing the application that a broken reference will be left behind. Whether this information is unwanted or not useful at all, it is enough not adding the property strictForeignRef to the field containing a ref. On the other hand where strictForeignRef is applied, the error can be catched by application and reported as a warning.