runtime-models

runtime-models is a NPM package, inspired by mongoose schemas, to create models at runtime with JS.

You can think of a model as a class. The difference being that classes create objects whereas models check objects to see if they are in conformity. This can be useful when you are validating an objects structure that wasn't made from a specific class, such as accepting POST requests.

Installation

NPM: npm install runtime-models

Usage

Creating a model

Models are made by creating an object with key-value pairs. These pairs reflect the key required and the type that the key must be.

VITAL ->If you want to use "type" or "required" as keys in your model, see "The Underscore Option"

const Model=require("runtime-models");
let bookModel=new Model({
  author: String,
  title: String,
  year: Number
})

Models can have multiple layers of depth, just like any javascript object

const Model=require("runtime-models");
let bookModel=new Model({
  author: String,
  title: String,
  year: Number
  cover: { //multiple layers
    artist: String
  }
});

To declare array types, you simply put the type ALONE inside an array:

const Model=require("runtime-models");
let bookModel=new Model({
  author: {
    name: String,
    otherBooks: [String] //otherbooks is now a String array
  },
  title: String,
  year: Number
  cover: {
    artist: String
  }
});

You can also use the objects of models as types, for example:

const Model=require("runtime-models");
const pageObj={
  number: Number,
  chapter: Number,
  text: String
}
let pageModel=new Model(pageObj);

let bookModel=new Model({
  author: {
    name: String,
    otherBooks: [String]
  },
  title: String,
  year: Number
  cover: {
    artist: String
  },
  pages: [pageObj] //pages now requires us to have an array of pages
});

Checking an object against a model

Checking objects is extremely simple-take the following code:

const Model=require("runtime-models");
let myModel=new Model({
  data: {
    word: String,
    num: Number
  }
});

let objOne={
  data:{
    word: "I am a word!",
    num: 5
  }
}

let objTwo={
  data:{

  }
}

let objThree={
  word: "I am also a word!",
  num: 4
}

myModel.check(objOne) //returns true
myModel.check(objTwo)//returns false
myModel.check(objThree) //returns false

The required option

You can make a field in the model optional. To do so is simple. Say we had this model

let model=new Model({
  num: Number,
  str: String
});

So, let's leave "num" as required, but make "str" optional.

let model=new Model({
  num: Number,
  str: {
    type: String,
    required: false
  }
})

Now, an object such as the following one passes our model check.

let myObj={num: 5};

The underscore option

Sometimes, you may want to use "type" or "required" as fields in your object. Normally this would be an issue, as those are keywords (as shown above). To get around this, the Model constructor takes an optional first boolean argument, which defaults to false. If true, "type" and "required" are both able to be used as fields. You simply use "_type" and "_required" instead. For example, all three of the following models function identically:

const model=new Model({
  name: {
    type: String,
    required: true
  }
});
const model2=new Model(false, {
  name: {
    type: String,
    required: true
  }
});
const model3=new Model(true, {
  name: {
    _type: String,
    _required: true
  }//Now we can use type and required as fields
});

checkStrict

In addition to check, models also have the checkStrict function. The only difference between check and checkStrict is that checkStrict will fail if the provided object has fields that are not in the model. For example:

let model=new Model({
  num: Number,
  str: String
});

let obj={
  num:5,
  str: "Hey",
  imposter: "oooo"
};

check would work here, as obj has all the fields of model. checkStrict would fail it as it has the extra "imposter" field.

Additional checks

In some cases, type checks wont be enough. To add more checks is simple. Let's say we had this model:

let model=new Model({
  id: String,
  num: 5
});

Let's say we want id to not only be a String, but a SPECIFIC String. To add that is simple. the model.alsoRequire function takes a function that, when passed the object being checked, returns true or false based on some criteria. For example:

let model=new Model({
  id: String,
  num: Number
});
model.alsoRequire(obj=>obj.id=="Some ID");

let objOne={
  id: "Some ID",
  num: 4
};
let objTwo={
  id: "Some other ID",
  num: 3
};
model.check(objOne) //true
model.check(objTwo)// false

Workflow

When checking an object, there are three possible stages of checking:

1. Check if object has keys (check)
2. Check if object has extra keys (checkStrict)
3. Check additional requirements for the object (made with alsoRequire)

Obviously, if you use check without any additional requirements, then only one stage will trigger-the first. However, if all these exist in your project, the order that these stages are listed in is the order that they will be triggered in. And that's it! Enjoy!