jmnuf / js-modeler

Project inspired by pydantic

Js Modeler

Inspired by pydantic, this is an object class modeler. This library holds 2 main things:

• The createModel function which takes 2 arguments (listed below) and returns a Model class with a structure based on the passed structure
• The Structs object with functions that create property structures for creating the desired type and handling of the property

createModel Arguments

• model_name: string which is just the class name per say, errors will show this name
• request_structure: ModelRequestStructure the structure of the generated Model

ModelRequestStructure

The ModelRequestStructure is based on the values from the functions in Structs and functions you declare there. This is essentially the shape of the class you want to make and what methods it should have. All functions passed are attached to the generated class's prototype so all class instances will have these functions as "methods"

Property Structures Structs

You can pass an object with the following keys to change behavior of the property strcture to the struct functions:

• default_value:T set the default value for the property
• required:boolean declare if the property is required to exist among the passed keys when creating a new Model instance Properties, defaults to true
• nullable:boolean declare if this property is allowed to be null, defaults to true

The following are the functions for creating property structures

• string: create a string property, defaults to non-null empty string
• int: create a number property that also checks if the number is an integer with Number.isInteger, defaults to 0
• number: create a number property, defaults to non-null 0.0
• bool: create a boolean property, defaults to non-null false
• bigint: create a BigInt property, defaults to non-null BigInt(0)
• map: create a Map<string, T> property, defaults to non-null Map<string, any>
• model: create a Model property, defaults to nullable null

Random Example

Just a minor example of what you could do with it though for validating post requests there's better stuff out there if you want a proper robust system

// Model declaration
const PostRequest = createModel('FormResult', {
  name: Structs.string(),
  // When setting data if in TS pass as the generic whether the property is required or not for proper intellisense, don't know how to handle this properly with typing :(
  email: Structs.string<false>({ required: false }),
  age: Structs.int(),
  type: Structs.string(),
  // For adding methods to the class, just add create the function as if here was the class declaration
  getIntroduction():string {
    return `Hello, my name is ${this.name} and I'm ${this.age} years old.`
  }
});

// Theoretical post request
app.post('/post', (req, res) => {
  let posted:PostRequest;
  try {
    posted = new PostRequest(req.body);
  } catch (e) {
    // Response sents how the sent body differs from the required params
    res.send(e.message);
    return;
  }
  /*
    Use posted data for something
  */
  res.send(posted.getIntroduction());
});