Sails.JS - Get the count of the number of objects/rows in the database

Question

In Sails.js, a lot of work is done for you by generating the models and controllers. The controllers allow for access to the data through API's. It allows for easy pagination by passing the start/skip/offset and take/limit. But in order for me to determine the maximum page of a collection I need to know how many items are in a collection.

I have tried to extend the blueprint in the generator to expose a new API method count and create the count action. According to the Waterline documentation, count is an action that can be called on the model. When I call User.count(), I get this:

{ _context: 
   { identity: 'user',
     adapter: 
      { syncable: false,
        defaults: [Object],
        registerCollection: [Function],
        create: [Function],
        find: [Function],
        update: [Function],
        destroy: [Function],
        count: [Function],
        identity: 'odata',
        globalId: 'odata',
        config: [Object] },
     attributes: {},
     _cast: { _types: [Object] },
     _schema: { context: [Circular], schema: [Object], hasSchema: true },
     _validator: { validations: {} },
     _callbacks: 
      { beforeValidation: [Object],
        afterValidation: [Object],
        beforeUpdate: [Object],
        afterUpdate: [Object],
        beforeCreate: [Object],
        afterCreate: [Object],
        beforeDestroy: [Object],
        afterDestroy: [Object] },
     _instanceMethods: {},
     autoPK: true,
     autoCreatedAt: true,
     autoUpdatedAt: true,
     hasSchema: true,
     migrate: 'alter',
     _model: { [Function] extend: [Function], inject: [Function], __super__: {} },
     _transformer: { _transformations: {} },
     _tableName: 'user',
     _adapterDefs: [ [Object] ],
     _adapter: 
      { adapter: [Object],
        adapterDefs: [Object],
        query: [Circular],
        collection: 'user' },
     syncable: [Function],
     defaults: [Function],
     registerCollection: [Function],
     config: [Function],
     findOneById: [Function: dynamicMethod],
     findOneByIdIn: [Function: dynamicMethod],
     findOneByIdLike: [Function: dynamicMethod],
     findById: [Function: dynamicMethod],
     findByIdIn: [Function: dynamicMethod],
     findByIdLike: [Function: dynamicMethod],
     countById: [Function: dynamicMethod],
     countByIdIn: [Function: dynamicMethod],
     countByIdLike: [Function: dynamicMethod],
     idStartsWith: [Function: dynamicMethod],
     idContains: [Function: dynamicMethod],
     idEndsWith: [Function: dynamicMethod],
     findOneByCreatedAt: [Function: dynamicMethod],
     findOneByCreatedAtIn: [Function: dynamicMethod],
     findOneByCreatedAtLike: [Function: dynamicMethod],
     findByCreatedAt: [Function: dynamicMethod],
     findByCreatedAtIn: [Function: dynamicMethod],
     findByCreatedAtLike: [Function: dynamicMethod],
     countByCreatedAt: [Function: dynamicMethod],
     countByCreatedAtIn: [Function: dynamicMethod],
     countByCreatedAtLike: [Function: dynamicMethod],
     createdAtStartsWith: [Function: dynamicMethod],
     createdAtContains: [Function: dynamicMethod],
     createdAtEndsWith: [Function: dynamicMethod],
     findOneByUpdatedAt: [Function: dynamicMethod],
     findOneByUpdatedAtIn: [Function: dynamicMethod],
     findOneByUpdatedAtLike: [Function: dynamicMethod],
     findByUpdatedAt: [Function: dynamicMethod],
     findByUpdatedAtIn: [Function: dynamicMethod],
     findByUpdatedAtLike: [Function: dynamicMethod],
     countByUpdatedAt: [Function: dynamicMethod],
     countByUpdatedAtIn: [Function: dynamicMethod],
     countByUpdatedAtLike: [Function: dynamicMethod],
     updatedAtStartsWith: [Function: dynamicMethod],
     updatedAtContains: [Function: dynamicMethod],
     updatedAtEndsWith: [Function: dynamicMethod] },
  _method: [Function],
  _criteria: {},
  _values: null }

Note: I am using a custom adapter, but I have created a count method for the adapter.

Fiorenza

User.count(yourCallbackFunction); – Cameral

Of course its callback based.. I don't know what I was thinking. That also explains what it was returning... the chain-able User object. – Fiorenza

I have not use sails, I think it should be User.count(function (err, num) { console.log(num); }); And if you defined a count method, it should be: count = function(callback) { User.count(callback) }; – Cameral

I got it now with your help. If you put the information in an answer, I will mark it as the correct one. – Fiorenza

I want to see how and where do you expose a count method to sails, can you write the answer? – Cameral

To keep stackoverflow organized, you can post the answer to this question here and then post another question for how to expose the count method to sails. I will answer it there. – Fiorenza

Answer 1

To get the count of the number of objects in user collection:

User.count(function (err, num) {
    if(err) {
       return console.log(err);
    }
    console.log(num);
});

To wrap User.count in another method:

yourMethod = function (callback) {
    User.count(callback);
}

Cameral

Is there any way to pass a query to the count function? The use case is to get the count for a subset of items in a collection that satisfy a certain condition. – Haldes

Answer 2

Now you can use sails installable hook to achieve count functionality through blueprint api methods.

I explained it in this answer: Get total count in Sails JS blueprint API

You can also pass query to the count function to get the count for a subset of items in a collection that satisfy a certain condition.

Boar