如何使用 express-validator 验证输入字段中的输入是否有 base64 编码字符串？
在 HTML 表单中，我们经常需要不同类型的验证。验证现有电子邮件、验证密码长度、验证确认密码、验证为仅允许整数输入，这些都是验证的一些示例。如果在某个输入字段中只允许 64 进制编码的字符串，即不允许任何其他形式的不构成 64 进制编码字符串的字符串。我们还可以使用 express-validator 中间件验证这些输入字段，使其只接受 base 64 编码的字符串。
安装快递验证器的命令:
npm install express-validator
使用快递验证器实现逻辑的步骤:
- Install the courier verifier middleware.
- Create a validator.js file to encode all validation logic.
- Validate the input through validateInputField: check (enter the field name) and chain on the validation isBase64 () with "."
- Use the validation name (validateInputField) in the route as the middleware and as a validation array.
- Destruct the' validationresult' function from express-validator and use it to find any errors.
- If an error occurs, redirect to the same page where the error message is sent.
- If the error list is empty, the user is allowed to access subsequent requests.
注意:这里我们使用本地或自定义数据库来实现逻辑，同样的步骤也可以在 MongoDB 或 MySql 这样的常规数据库中实现逻辑。
示例:此示例说明如何验证输入字段，使其仅接受 64 位编码字符串。
文件名–index . js
【JavaScript】
const express = require('express')
const bodyParser = require('body-parser')
const {validationResult} = require('express-validator')
const repo = require('./repository')
const { validateBase64Data } = require('./validator')
const formTemplet = require('./form')
const app = express()
const port = process.env.PORT || 3000
// The body-parser middleware to parse form data
app.use(bodyParser.urlencoded({extended : true}))
// Get route to display HTML form
app.get('/', (req, res) => {
res.send(formTemplet({}))
})
// Post route to handle form submission logic and
app.post(
'/data',
[validateBase64Data],
async (req, res) => {
const errors = validationResult(req)
if(!errors.isEmpty()){
return res.send(formTemplet({errors}))
}
const {name, base64data} = req.body
await repo.create({
name,
base64data
})
res.send('<h2>Base 64 data decoded and '
+ 'Stored successfully in the database</h2>')
})
// Server setup
app.listen(port, () => {
console.log(`Server start on port ${port}`)
})
Filename–repository . js:该文件包含创建本地数据库并与之交互的所有逻辑。
JavaScript
// Importing node.js file system module
const fs = require('fs')
const { base64decode } = require('nodejs-base64');
class Repository {
constructor(filename) {
// The filename where datas are going to store
if(!filename) {
throw new Error(
'Filename is required to create a datastore!')
}
this.filename = filename
try {
fs.accessSync(this.filename)
} catch(err) {
// If file not exist it is created
// with empty array
fs.writeFileSync(this.filename, '[]')
}
}
// Get all existing records
async getAll(){
return JSON.parse(
await fs.promises.readFile(this.filename, {
encoding : 'utf8'
})
)
}
// Create new record
async create(attrs){
// Fetch all existing records
const records = await this.getAll()
// Decode base64 encoded data
const data = base64decode(attrs.base64data)
// New record
const record = {
name:attrs.name,
data
}
// All the existing records with
// new record push back to database
records.push(record)
await fs.promises.writeFile(
this.filename,
JSON.stringify(records, null, 2)
)
return record
}
}
// The 'datastore.json' file created at runtime
// and all the information provided via signup form
// store in this file in JSON format.
module.exports = new Repository('datastore.json')
文件名-表单. js: 该文件包含显示 HTML 表单的逻辑。
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='https://cdnjs.cloudflare.com/ajax/libs/bulma/0.9.0/css/bulma.min.css'>
<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='/data' method='POST'>
<div>
<div>
<label class='label' id='name'>
Name
</label>
</div>
<input class='input' type='text'
name='name'
placeholder='Submitted By'
for='name'>
</div>
<div>
<div>
<label class='label' id='base64data'>
Base 64 data
</label>
</div>
<input class='input' type='text'
name='base64data'
placeholder='Base 64 Encode data'
for='base64data'>
<p class="help is-danger">
${getError(errors, 'base64data')}
</p>
</div>
<div>
<button class='button is-primary'>
Submit
</button>
</div>
</form>
</div>
</div>
</div>
</body>
</html>
`
}
Filename–validator . js:该文件包含所有验证逻辑(验证输入字段只接受基本编码 64 字符串的逻辑)
JavaScript
const {check} = require('express-validator')
const repo = require('./repository')
module.exports = {
validateBase64Data : check('base64data')
// To delete leading and triling space
.trim()
// Validate input field to accept only base32 string
.isBase64()
// Custom message
.withMessage('Must be a Base 64 encoded string')
}
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