Enhance your Sails.js model by incorporating a custom instance method as a new property

Question

Enhance your Sails.js model by incorporating a custom instance method as a new property

As a JavaScript programmer still learning the ropes, I encountered a challenge while working with Sails.js and creating a model. Here is what I have so far:

module.exports = {

    tableName: 'FOO_TABLE',

    attributes: {
        FOO: 'string',
        BAR: 'number',
        BAR2: function() {
            return this.BAR + 1;
        }
    },

};

In my controller, I retrieve all instances like this:

FOO_MODEL.find().exec(function(err, FOOS) {
    return res.view({data: JSON.stringify(FOOS)});
});

The issue lies in the fact that the BAR2 method is missing within the FOOS data. To address this, I used Underscore.js as follows:

FOOS = _.map(FOOS, function(FOO){ FOO.BAR2 = FOO.BAR2(); return FOO; });

However, I am not satisfied with this solution and fear encountering similar problems in the future. How would you handle this scenario more efficiently? Thank you.

javascript node.js sails.js

Answer 1

Answer №1

If you simply want to assign a calculated value to each new instance, consider defining BAR2 as a type number in the model (instead of a function), and implement a beforeCreate class method like this:

beforeCreate: function(values, cb) {
  values.BAR2 = values.BAR + 1;
  return cb();
}

If you prefer to maintain BAR2 as an instance method and include it in the object serialization process, you can customize the default toJSON instance method like so:

toJSON: function() {
   var obj = this.toObject();
   obj.BAR2 = obj.BAR2();
   return obj;
}

Whenever an instance is converted into a string representation, its toJSON method will be invoked.

Answer 2

If you simply want to assign a calculated value to each new instance, consider defining BAR2 as a type number in the model (instead of a function), and implement a beforeCreate class method like this:

beforeCreate: function(values, cb) {
  values.BAR2 = values.BAR + 1;
  return cb();
}

If you prefer to maintain BAR2 as an instance method and include it in the object serialization process, you can customize the default toJSON instance method like so:

toJSON: function() {
   var obj = this.toObject();
   obj.BAR2 = obj.BAR2();
   return obj;
}

Whenever an instance is converted into a string representation, its toJSON method will be invoked.

Answer 3

Answer №2

Ensure Accuracy of Query Results

If you are executing your instance-method within a query-callback while handling a request, it is crucial to verify the result you are receiving.

In my personal experience, I mistakenly used the Sails/Waterline ORM Model method find instead of findOne, resulting in returning a collection (an array). This led me to attempt something like:

[ {...} ].hasItem(id)

... when I should have been using:

myQueryResults[0].hasItem(id)

Alternatively, making sure to use findOne for the query would have prevented this confusion. Mistakes happen, but learning from them is key.

I hope this information proves useful!

Answer 4

Ensure Accuracy of Query Results

If you are executing your instance-method within a query-callback while handling a request, it is crucial to verify the result you are receiving.

In my personal experience, I mistakenly used the Sails/Waterline ORM Model method find instead of findOne, resulting in returning a collection (an array). This led me to attempt something like:

[ {...} ].hasItem(id)

... when I should have been using:

myQueryResults[0].hasItem(id)

Alternatively, making sure to use findOne for the query would have prevented this confusion. Mistakes happen, but learning from them is key.

I hope this information proves useful!

Enhance your Sails.js model by incorporating a custom instance method as a new property

Answer №1

Answer №2

Ensure Accuracy of Query Results

Similar questions

Extracting elements using Node.js and Selenium

Retrieving data from an HTML input tag and storing it in a variable

"Although disabled, input elements can still be focused on in Firefox browser

I attempted to host my MERN stack application on a shared hosting platform, but encountered the error message stating "Unable to obtain lock for the application."

Adding content to a text field and then moving to the next line

Having trouble with loading images from the assets folder, keep encountering a 304 error

Encountering a "Cannot GET /PATH" error while developing a NUXT application due to a DOT present in

Guide on accessing the text content within a div element in HTML by triggering a button click

Encountering a React clash while integrating Material UI

The issue I am facing is that the map function is not functioning correctly when I click

Node.js user attempting to upload and handle files without any external libraries, solely relying on traditional JavaScript and HTML techniques

When the page is refreshed, reorienting axes in three.js encounters difficulties

Are you unsure whether to use Ajax or jQuery? If you need assistance in adding parameters to

I am encountering an issue when trying to containerize a Node.js application with MongoDB using Docker

Waiting to run a function until a specified function has finished its execution

Swapping out the default JavaScript random number generator for my custom JSON-based solution

What is the best approach for retrieving specific data from MongoDB in a Node.js application using the GET method?

The jQuery toggleClass() function is not being applied successfully to content that is dynamically generated from

Sending arguments from JavaScript to PHP via ajax

What is the process for incorporating Material-UI into a JSFiddle project?