How to validate if input date (start date) in input field must be before a given date (end date) using express-validator ?
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 before some given date (Ex: ‘start date’ must come before ‘end 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 end date as the 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 { validateStartDate } = 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' ,
[validateStartDate],
async (req, res) => {
const errors = validationResult(req)
if (!errors.isEmpty()) {
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' href=
<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' >
<p class="help is-danger">
${getError(errors, 'sdate' )}
</p>
</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' >
</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 before a given date).
javascript
const { check } = require( 'express-validator' )
const repo = require( './repository' )
module.exports = {
validateStartDate: check( 'sdate' )
.trim()
.custom((sdate, { req }) => {
const [sd, sm, sy] = sdate.split( '/' )
const [ed, em, ey] = req.body.edate.split( '/' )
const startDate = new Date(sy, sm, sd)
const endDate = new Date(ey, em, ed)
if (startDate >= endDate) {
throw new Error(
'Start date of project must be before End date' )
}
return true
})
}
|
Filename – package.json
Package.json file
Database:
Database
Output:
Attempt to submit form when start date comes after end date
Response when attempt to submit the form where start date comes after end date
Attempt to submit form when start date comes before end date
Response when attempt to submit the form where end date comes after start date
Database after successful form submission:
Note: We have used some Bulma classes(CSS framework) in the signup.js file to design the content.
Last Updated :
08 Apr, 2022
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