In this blog, we will see how to use Joi library for object and arrays validation. Object validation is very important on the front-end side to restrict users from entering valid data and also important on the back-end side to verifying what goes into our REST API won’t break our code.
Joi is the powerful npm library to validate the JavaScript object when we need to perform these checks, like validating response from a backend endpoint. First, let’s see the available libraries for validating the JavaScript object. Below is the list of some popular libraries for object validation features:
1. ajv
4. decoders
Let’s see how to use Joi to validate javascript objects step by step in the Express application.
1. Define package.json file:
First, create a project folder and define package.json file init for that; write the below command.
npm init -y
2. Installations:
First, create the express application and Install the Joi library. Next, you need to write the below line in your terminal.
npm install Joi
3. Creating Schema:
After successful installation, you must import Joi and create the schema for the object we need to validate. In the schema, we set up some rules specific to each value in the object. Let’s see how to create a schema.
const Joi = require('Joi'); //Joi schema to validate the object data const schema = Joi.object().keys({ name: Joi.string().alphanum().min(3).max(30).required(), email: Joi.string().email() }); const dataToValidate = { Name: “John”, email: “john@domain.com” } const result = Joi.validate(dataToValidate, schema); // result.error == null means valid
In the above code, we have created a schema for our API payload where we have two fields. And we are validating both of the fields with the help of Joi.
Here, what we are doing is two things:
First, we are constructing a schema for that we are using Joi. object() method, and then we are validation our data object using Joi. validate() method.
If our data is valid, then Joi. validate(schema, dataToValidate) will return null otherwise, it will return the error object and based on the return value, we can send the status of the API.
4. Constructor Support:
We can validate the data for all the primitives as we as regex. And we can also be nested to any depth. Let’s see some basic constructors that we can use to validate the data with Joi.
I suggest you to have a look into the Joi API where you can find all the methods that we can use for validation.
5. Validating Nested Object:
So we have only shown how to create schema so far that is one level deep. Now let’s see how to create the nested schema.
const personalData = Joi.object().keys({ name: Joi.string().alphanum().min(3).max(30).required(), email: Joi.string().required(), address: Joi.object.keys({ country: Joi.string().required(), state: Joi.string().required(), city: Joi.string().required(), zip_code: Joi.number().required() })) });
Here we have a nested schema. The address schema looks exactly like the outer call we first make. Nesting is as easy as that.
6. Joi As A Middleware:
We can use Joi as middleware and use it every time we need validation. With this approach, we can eliminate extra code in every API for validation. For creating middleware, first, create a middleware folder in the project directory, and in that folder, create validationMiddleWare.js. In this file, add write below code.
exports.validate = (schema) => (req, res, next) => { const { error } = schema.validate(req.body); if (error) { res.status(422) .send(error.details[0].message); } else { next(); } };
It will receive a schema and check our req.body against the schema.
Now, create a file called validation.js. This will hold our schemas. Paste the following code into it.
const Joi = require("joi"); exports.person = Joi.object() .keys({ name: Joi.string() .min(3) .max(40) .required(), age: Joi.number() .integer() .min(16) });
Now create an API like so, after importing both files.
const validation = require('./validation') const { validate } = require('./validationMiddleware') app.post("/", validate(validation.person), (req, res) => { res.send("request processed"); }); const validation = require('./validation') const { validate } = require('./validationMiddleware') app.post("/", validate(validation.person), (req, res) => { res.send("request processed"); });
In this blog, we saw how to validate objects and arrays with the help of Joi and what schema is, constructor support while creating a schema and how to validate the data. Then, at last, we saw the advantages of using Joi. Thank you for reading! In case you have any questions, feel free to comment.
Nadeem is a front-end developer with 1.5+ years of experience. He has experience in web technologies like React.js, Redux, and UI frameworks. His expertise in building interactive and responsive web applications, creating reusable components, and writing efficient, optimized, and DRY code. He enjoys learning about new technologies.
Mindbowser played a crucial role in helping us bring everything together into a unified, cohesive product. Their commitment to industry-standard coding practices made an enormous difference, allowing developers to seamlessly transition in and out of the project without any confusion....
CEO, MarketsAI
I'm thrilled to be partnering with Mindbowser on our journey with TravelRite. The collaboration has been exceptional, and I’m truly grateful for the dedication and expertise the team has brought to the development process. Their commitment to our mission is...
Founder & CEO, TravelRite
The Mindbowser team's professionalism consistently impressed me. Their commitment to quality shone through in every aspect of the project. They truly went the extra mile, ensuring they understood our needs perfectly and were always willing to invest the time to...
CTO, New Day Therapeutics
I collaborated with Mindbowser for several years on a complex SaaS platform project. They took over a partially completed project and successfully transformed it into a fully functional and robust platform. Throughout the entire process, the quality of their work...
President, E.B. Carlson
Mindbowser and team are professional, talented and very responsive. They got us through a challenging situation with our IOT product successfully. They will be our go to dev team going forward.
Founder, Cascada
Amazing team to work with. Very responsive and very skilled in both front and backend engineering. Looking forward to our next project together.
Co-Founder, Emerge
The team is great to work with. Very professional, on task, and efficient.
Founder, PeriopMD
I can not express enough how pleased we are with the whole team. From the first call and meeting, they took our vision and ran with it. Communication was easy and everyone was flexible to our schedule. I’m excited to...
Founder, Seeke
Mindbowser has truly been foundational in my journey from concept to design and onto that final launch phase.
CEO, KickSnap
We had very close go live timeline and Mindbowser team got us live a month before.
CEO, BuyNow WorldWide
If you want a team of great developers, I recommend them for the next project.
Founder, Teach Reach
Mindbowser built both iOS and Android apps for Mindworks, that have stood the test of time. 5 years later they still function quite beautifully. Their team always met their objectives and I'm very happy with the end result. Thank you!
Founder, Mindworks
Mindbowser has delivered a much better quality product than our previous tech vendors. Our product is stable and passed Well Architected Framework Review from AWS.
CEO, PurpleAnt
I am happy to share that we got USD 10k in cloud credits courtesy of our friends at Mindbowser. Thank you Pravin and Ayush, this means a lot to us.
CTO, Shortlist
Mindbowser is one of the reasons that our app is successful. These guys have been a great team.
Founder & CEO, MangoMirror
Kudos for all your hard work and diligence on the Telehealth platform project. You made it possible.
CEO, ThriveHealth
Mindbowser helped us build an awesome iOS app to bring balance to people’s lives.
CEO, SMILINGMIND
They were a very responsive team! Extremely easy to communicate and work with!
Founder & CEO, TotTech
We’ve had very little-to-no hiccups at all—it’s been a really pleasurable experience.
Co-Founder, TEAM8s
Mindbowser was very helpful with explaining the development process and started quickly on the project.
Executive Director of Product Development, Innovation Lab
The greatest benefit we got from Mindbowser is the expertise. Their team has developed apps in all different industries with all types of social proofs.
Co-Founder, Vesica
Mindbowser is professional, efficient and thorough.
Consultant, XPRIZE
Very committed, they create beautiful apps and are very benevolent. They have brilliant Ideas.
Founder, S.T.A.R.S of Wellness
Mindbowser was great; they listened to us a lot and helped us hone in on the actual idea of the app. They had put together fantastic wireframes for us.
Co-Founder, Flat Earth
Ayush was responsive and paired me with the best team member possible, to complete my complex vision and project. Could not be happier.
Founder, Child Life On Call
The team from Mindbowser stayed on task, asked the right questions, and completed the required tasks in a timely fashion! Strong work team!
CEO, SDOH2Health LLC
Mindbowser was easy to work with and hit the ground running, immediately feeling like part of our team.
CEO, Stealth Startup
Mindbowser was an excellent partner in developing my fitness app. They were patient, attentive, & understood my business needs. The end product exceeded my expectations. Thrilled to share it globally.
Owner, Phalanx
Mindbowser's expertise in tech, process & mobile development made them our choice for our app. The team was dedicated to the process & delivered high-quality features on time. They also gave valuable industry advice. Highly recommend them for app development...
Co-Founder, Fox&Fork