How to handle multiple inputs in React

#react #webdev #codenewbie

I recently had to refactor a React Form when working with multiple inputs and I thought I'd share how I did it.

This is how my form looks like:

The Problem

Look at the starter code below
This Form component has 5 input fields in total; 5 different states and 5 different onChange inline functions
This is not exactly DRY code 🙀

import React, { useState } from "react";

export default function Form() {
  const [newCompany, setCompany] = useState("");
  const [newPosition, setPosition] = useState("");
  const [newLink, setNewLink] = useState("");
  const [newDate, setNewDate] = useState("");
  const [newNote, setNewNote] = useState("");

  return (
        <form>
          <input
            value={newCompany}
            onChange={(e) => setCompany(e.target.value)}
            label="Company"
          />
          <input
            value={newPosition}
            onChange={(e) => setPosition(e.target.value)}
            label="Job Title"
          />
          <input
            value={newLink}
            onChange={(e) => setNewLink(e.target.value)}
            label="Job Link"
          />
          <input
            type="date"
            value={newDate}
            onChange={(e) => setNewDate(e.target.value)}
          />
          <input
            value={newNote}
            onChange={(e) => setNewNote(e.target.value)}
            label="Note"
          />
          <button type="submit"> Submit </button>
        </form>
  );
}

Also, if I want to add a reset function later, my code will look like this: 🙅🏽‍♀️

  const reset = () => {
    setCompany("");
    setPosition("");
    setNewLink("");
    setNewDate("");
    setNewNote("");
  };

The Solution: Refactoring ✨

Step 1: Add input default values and initialize state

First, let's add default values to ALL input fields
How do we do that? We create an object literal with those values and set to empty string
Then, with the useState() React Hook we initialize our values state with the initialValues object
Important: Remember to add the value attribute to every input field with its corresponding value (e.g. values={values.company})

const initialValues = {
  company: "",
  position: "",
  link: "",
  date: "",
  note: "",
};

export default function Form() {
  const [values, setValues] = useState(initialValues);

  return (
        <form>
          <input
            value={values.company}
            onChange={(e) => setCompany(e.target.value)}
            label="Company"
          />
 //...

Step 2: Handle multiple input change

The goal here is to handle ALL inputs with a single onChange handler
In order to update and keep track of our input fields every time they change, we need to create a handleInputChange function (see below)
What's happening here? (quick recap)
- First, we're using object destructuring to get or extract the name and the value attributes from our inputs (look at the the comments below - they're equivalent)
- Then, we're updating our values state object with the existing values by using the setValues() function and the spread operator
- And finally, we're updating the value of the event that was triggered by that onChange with this ES6 syntax: [name]: value
- This is a very important step! We need to add a name attribute to our inputs and [name]: value here means that we're setting a dynamic name property key (taken from our inputs - e.g. company: e.target.value) which will be equal to the value of our current input state.

Reference: React Docs

 //... 

  const handleInputChange = (e) => {
    //const name = e.target.name 
    //const value = e.target.value 
    const { name, value } = e.target;

    setValues({
      ...values,
      [name]: value,
    });
  };

  return (
        <form>
          <input
            value={values.company}
            onChange={handleInputChange}
            name="company" //IMPORTANT 
            label="Company"
          />
   // ...

Step 3: Add `handleInputChange` to input fields

Add the handleInputChange function to the onChange prop of every input field
Look at the final code; this is a much cleaner and manageable form 👌🏽

import React, { useState } from "react";

const initialValues = {
  company: "",
  position: "",
  link: "",
  date: "",
  note: "",
};

export default function Form() {
  const [values, setValues] = useState(initialValues);

  const handleInputChange = (e) => {
    const { name, value } = e.target;
    setValues({
      ...values,
      [name]: value,
    });
  };

  return (
        <form>
          <input
            value={values.company}
            onChange={handleInputChange}
            name="company"
            label="Company"
          />
          <input
            value={values.position}
            onChange={handleInputChange}
            name="position"
            label="Job Title"
          />
           // ... Rest of the input fields
          <button type="submit"> Submit </button>
        </form>
  );
}

I hope it was useful. All comments and feedback are welcome! 🎊

Top comments (22)

Musawer Shah • Dec 2 '21

Hi this method works fine for multiple input but just with normal input fields. What if their are some booleans and arrays??? E.g In vue.js I have the following data model which change at some point in time, which in that case two way data binding make it way easier for us.

data() {
        return {
            valid: false,
            showDialog: true,
            showFullLoading: false,
            isImage: false,
            product: {
                name_en: "",
                name_ar: "",
                category: "",
                subcategory: "",
                description_en: "",
                description_ar: "",
                meta_title: "",
                meta_description: "",
                meta_keywords: "",
                price: 0.0,
                showSale: false,
                sale: 0.0,
                image: "",
                saleAfterStock: false,
                stock: 10
            },
            images: [
                { image: null, isImage: false, id: shortid.generate() },
                { image: null, isImage: false, id: shortid.generate() },
                { image: null, isImage: false, id: shortid.generate() },
                { image: null, isImage: false, id: shortid.generate() }
            ],
            attributes: [],
            defaultVariants: [],
            dataWeightClass: ["Gram", "Kilo Gram", "Pound"],
            dataDimensionClass: ["Centimeter", "Inch"],
            showAttributeDialog: false,
            sizeGuide: false,
            sizeGuides: [],
            attribute: {
                title_en: "",
                title_ar: "",
                description_en: "",
                description_ar: "",
                image: null,
                isImage: false
            },
            subcategories: [],
            options: [],
            variantsHeaders: [
                { text: "Variant", value: "name" },
                { text: "Price", value: "price" },
                { text: "Stock", value: "quantity" },
                { text: "Visibility", value: "visibility" }
            ],
            defaultVariantId: "",
            defaultPreviewId: ""
        };
    },

jgifford82 • Sep 14 '22

Thank you so much!! I'm learning about controlled forms, and this has been incredibly helpful!

donchocska • Dec 14 '20

Amazing perofrmance. Very thanks!

tombohub • Dec 7 '22 • Edited

very good , but I don't like it. Now you have to maintain the names of the inputs, which is a string. It's a bug waiting to happen.

I suggest using this solution: stackoverflow.com/a/47707719/1079002

btw, do you have solution for nested objects? I need that, thanks!

Sparsh Gupta • May 1 '22

Hi, just wanted to ask ,
since we are changing the state in handleInputChange
therefore, every time we will type in something the whole component will re-render since the state is changing
so isn't it an expensive approach in respect to performance?