猫鼬（mongodb）返回boolean query.exec吗？

Question

I try to make a library for use in node.js with mongoose (mongoDB). In my library, I want simply check if a user is_admin (group admin) or not.

Here is my model :

var mongoose = require('mongoose');

module.exports = mongoose.model('UsersGroups',{
    user_id: String,
    group_id: String
});

Here is my library :

var UsersGroups = require('../models/users_groups');

is_admin = function(userid)
{
    console.log('USERID : '+userid);
    var query = UsersGroups.find({'user_id': userid});
    query.select('user_id');
    query.where('group_id').equals('54d2264ed9b0eb887b7d7638');
    return query.exec();
}

module.exports = is_admin;

I want to the query return true or false .

I call the library like this :

var is_admin = require('../library/mylib.js');

...

if (is_admin(group.user_id))
{
  console.log('IS_ADMIN');
}
else
{
 console.log('NOT_ADMIN');
}

Someone can coach me for this?

Answer 1

query.exec() return Promise not Boolean Using mongoose Schema and Model will give more nice feature;

Example User Model

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
    name: { type: String, required: true, trim: true }
    // set user types as enumeration
    type: { type: String, enum: ["admin", "user", "guest"], required: ture, default: 'user' }
});

var User = mongoose.model('User', UserSchema);

User.prototype.isAdmin = function(){
    return this.type === "admin";
}

module.exports = User;

On controller

var user = require('model/user');

user.findById("54d2264ed9b0eb887b7d7638", function(err, user){
    if(err) 
        return console.error(err.stack);

    if(!user) 
        return console.error("User not found!");

    if(!user.isAdmin())
        console.log("User is not admin");
    else
        console.log("User is admin");
});

If you want to check with user group, you can change isAdmin function as you want

Answer 2

You can just run this query

UsersGroups.find({'user_id': userid, 'group_id': '54d2264ed9b0eb887b7d7638'}).count().exec();

it will find the matching pair - return 1 if it exists which is truthy in javascript. If it does not exist it will return 0 which is falsy so you will be able to use it inside if statements