const uniqueValidator = require('mongoose-unique-validator'); module.exports = mongoose => { var schema = mongoose.Schema( { message_token: String, site: Number }, { collection: 'message_token', timestamps: true } ); schema.method("toJSON", function() { const { __v, _id, ...object } = this.toObject(); object.id = _id; return object; }); schema.plugin(uniqueValidator); const MessageToken = mongoose.model("message_token", schema); return MessageToken; };