How to validate if input date (end date) in input field must be after a given date (start date) using express-validator ?
Last Updated :
06 Feb, 2023
In HTML forms, we often required validation of different types. Validate existing email, validate password length, validate confirm password, validate to allow only integer inputs, these are some examples of validation. In certain cases, we want the user to type a date that must come after some given date(Ex. ‘end date’ must be after ‘start date’) and based on that we give the user access to the request or deny the request access. We can also validate these input fields using express-validator middleware.
Command to install express-validator:
npm install express-validator
Steps to use express-validator to implement the logic:
- Install express-validator middleware.
- Create a validator.js file to code all the validation logic.
- Use custom validator to validate and fetch the start date as request body.
- Convert the date strings to a valid date and compare them according to requirement.
- Use the validation name(validateInputField) in the routes as a middleware as an array of validations.
- Destructure ‘validationResult’ function from express-validator to use it to find any errors.
- If error occurs redirect to the same page passing the error information.
- If error list is empty, give access to the user for the subsequent request.
Note: Here we use local or custom database to implement the logic, the same steps can be followed to implement the logic in a regular database like MongoDB or MySql.
Example: This example illustrates how to validate a input field to only allow a date after a given date.
Filename – index.js
Javascript
const express = require( 'express' )
const bodyParser = require( 'body-parser' )
const {validationResult} = require( 'express-validator' )
const repo = require( './repository' )
const { validateEndDate } = require( './validator' )
const formTemplet = require( './form' )
const app = express()
const port = process.env.PORT || 3000
app.use(bodyParser.urlencoded({extended : true }))
app.get( '/' , (req, res) => {
res.send(formTemplet({}))
})
app.post(
'/project' ,
[validateEndDate],
async (req, res) => {
const errors = validationResult(req)
if (!errors.isEmpty()) {
console.log(errors)
return res.send(formTemplet({errors}))
}
const {name, domain, sdate, edate, } = req.body
const [sd, sm, sy] = sdate.split( '/' )
const [ed, em, ey] = edate.split( '/' )
await repo.create({
'Project Name' : name,
'Project Domain' : domain,
'Start Date' : new Date(sy, sm-1, sd).toDateString(),
'End Date' : new Date(ey, em-1, ed).toDateString()
})
res.send( '<strong>Project details stored '
+ 'successfully in the database</strong>' )
})
app.listen(port, () => {
console.log(`Server start on port ${port}`)
})
|
Filename – repository.js: This file contains all the logic to create a local database and interact with it.
Javascript
const fs = require( 'fs' )
class Repository {
constructor(filename) {
if (!filename) {
throw new Error(
'Filename is required to create a datastore!' )
}
this .filename = filename
try {
fs.accessSync( this .filename)
} catch (err) {
fs.writeFileSync( this .filename, '[]' )
}
}
async getAll(){
return JSON.parse(
await fs.promises.readFile( this .filename, {
encoding : 'utf8'
})
)
}
async create(attrs){
const records = await this .getAll()
records.push(attrs)
await fs.promises.writeFile(
this .filename,
JSON.stringify(records, null , 2)
)
return attrs
}
}
module.exports = new Repository( 'datastore.json' )
|
Filename – form.js: This file contains logic to show the form to submit project data with start and end date.
Javascript
const getError = (errors, prop) => {
try {
return errors.mapped()[prop].msg
} catch (error) {
return ''
}
}
module.exports = ({errors}) => {
return `
<!DOCTYPE html>
<html>
<head>
<link rel= 'stylesheet'
<style>
div.columns{
margin-top: 100px;
}
.button{
margin-top : 10px
}
</style>
</head>
<body>
<div class= 'container' >
<div class= 'columns is-centered' >
<div class= 'column is-5' >
<form action= '/project' method= 'POST' >
<div>
<div>
<label class= 'label' id= 'name' >Project Name</label>
</div>
<input class= 'input' type= 'text' name= 'name'
placeholder= 'Project Name' for = 'name' >
</div>
<div>
<div>
<label class= 'label' id= 'domain' >Project Domain</label>
</div>
<input class= 'input' type= 'text' name= 'domain'
placeholder= 'Project Domain' for = 'base64data' >
</div>
<div>
<div>
<label class= 'label' id= 'sdate' >Start Date</label>
</div>
<input class= 'input' type= 'text' name= 'sdate'
placeholder= 'dd/mm/yyyy' for = 'sdate' >
</div>
<div>
<div>
<label class= 'label' id= 'edate' >End Date</label>
</div>
<input class= 'input' type= 'text' name= 'edate'
placeholder= 'dd/mm/yyyy' for = 'edate' >
<p class= "help is-danger" >${getError(errors, 'edate' )}</p>
</div>
<div>
<button class= 'button is-primary' >Submit</button>
</div>
</form>
</div>
</div>
</div>
</body>
</html>
`
}
|
Filename – validator.js: This file contain all the validation logic(Logic to validate a input field to accept only a date after a given date).
Javascript
const {check} = require( 'express-validator' )
const repo = require( './repository' )
module.exports = {
validateEndDate : check( 'edate' )
.trim()
.custom((edate, {req}) => {
const [sd, sm, sy] = req.body.sdate.split( '/' )
const [ed, em, ey] = edate.split( '/' )
const startDate = new Date(sy, sm, sd)
const endDate = new Date(ey, em, ed)
if (endDate <= startDate) {
throw new Error(
'End date of project must be after start date' )
}
return true
})
}
|
Filename – package.json
package.json file
Database:
Database
Output:
Attempt to submit form when end date comes before start date
Response when an attempt to submit the form where end date comes before start date
Attempt to submit form when end date comes after start date
Response when attempt to submit the form where end date comes after start date
Database after successful form submission:
Database after successful submission of form
Note: We have used some Bulma classes(CSS framework) in the signup.js file to design the content.
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