Ensure thorough validation of the JSON.parsed data in TypeScript

Question

Ensure thorough validation of the JSON.parsed data in TypeScript

Currently, I am developing a small module for Angular and I have encountered an issue regarding the condition where I verify my JSON.parsed data.

read(): Position|null {
    try {
        ...
        let parsedData  = JSON.parse(data);
        if (parsedData && parsedData.x && parsedData.y)
            return new Position(parsedData.x, parsedData.y);
    } catch (e) {
        ...
    }
    return null;
}

I find this solution to be suboptimal as it would require me to check for each property if there are more properties in the object that I had previously stringified. Additionally, I am unsure about how to handle cases when the parsed data is null. Are there any alternative solutions for validating the stringified data? Thank you

angular typescript if-statement conditional-statements javascript-objects

Answer 1

Answer №1

To transform your json output into a Position instance, all you need to do is cast it in the following manner:

read(): Position|null {
    try {
        return JSON.parse(data) as Position;
    } catch (e) {
        return null;
    }
}

Nevertheless, casting alone does not validate the data structure. It does not verify if the json contains the expected fields of the Position object. To ensure this, manual validation of each field is necessary.

An approach to achieve this could involve maintaining a list of properties within the class and then checking for their existence post-casting:

class Position {
    public x: Number;
    public y: Number;
    public someOtherField: string;
    
    public static PropertyNames: string[] = ["x", "y", "someOtherField"];
    public static isValid(pos: Position): Boolean {
        return Position.PropertyNames.every((i) => pos && pos.hasOwnProperty(i));
    }
}

let obj = new Position();
alert(Position.isValid(obj)); //false

obj.x = null;
obj.y = null;
obj.someOtherField = null;

alert(Position.isValid(obj)); //true

Answer 2

To transform your json output into a Position instance, all you need to do is cast it in the following manner:

read(): Position|null {
    try {
        return JSON.parse(data) as Position;
    } catch (e) {
        return null;
    }
}

Nevertheless, casting alone does not validate the data structure. It does not verify if the json contains the expected fields of the Position object. To ensure this, manual validation of each field is necessary.

An approach to achieve this could involve maintaining a list of properties within the class and then checking for their existence post-casting:

class Position {
    public x: Number;
    public y: Number;
    public someOtherField: string;
    
    public static PropertyNames: string[] = ["x", "y", "someOtherField"];
    public static isValid(pos: Position): Boolean {
        return Position.PropertyNames.every((i) => pos && pos.hasOwnProperty(i));
    }
}

let obj = new Position();
alert(Position.isValid(obj)); //false

obj.x = null;
obj.y = null;
obj.someOtherField = null;

alert(Position.isValid(obj)); //true

Ensure thorough validation of the JSON.parsed data in TypeScript

Answer №1

Similar questions

What is the best way to include an item in a list with a specific identifier using the useState Record data type in a React application built with TypeScript?

Angular is detecting an incorrect value in the mask

Revamping every Angular component

Angular 6 Subscription Service Does Not Trigger Data Sharing Events

Demonstrating the transformation of child elements into parent elements through angular 6 ngFor

The process of retrieving input field values from a table within an Angular reactive form

Angular module cannot be located

Saving the authenticated user's information from Firebase (including first name, last name, gender, and more) directly to our database

Tips for optimizing the performance of an Angular 2 website

An issue with the HTTP GET Request method is that it often sends "?" instead of "/"

Struggling with aligning mat-icon in the center using HTML and CSS?

Ensure the cursor is continually grabbing while moving items within a list using the @angular/cdk/drag-drop functionality

Continuously refreshing the information displayed in the Angular view that is linked to a function in the TypeScript file whenever a modification is identified

Extending Angular 2 functionality from a parent component

The issue with NGX-Bootstrap/Angular Pagination arises when attempting to adjust the maxSize input while the screen view (width) is being altered

Typescript: object containing at least one property with the type T assigned

Tips for displaying bar chart labels effectively with ChartJS

Necessitating derived classes to implement methods without making them publicly accessible

A Guide to Effectively Managing Express API Responses in Angular 2

Is there a way to reduce the version of npm in a nodejs project?