D:\nodejs_mongodb_project>npm install --save express-validator

Add the following code in the controller

const { check, validationResult } = require('express-validation')
exports.admin_regi_add = function (req, res) {

    check('fullname').isLength({ min: 3 }),
        check('fullname').isLength({ min: 3 }),
        check('mobile').isLength({ min: 3 }),
        check('pword').isLength({ min: 3 }),
        check('cpword').isLength({ min: 3 }),
        check('birth').isLength({ min: 3 }),
        check('sex').isLength({ min: 3 }),
        check('prefer_con').isLength({ min: 3 }),
        check('profile_pic').isLength({ min: 3 }),
        check('email').isEmail()

    const errors = validationResult(req)
    if (!errors.isEmpty()) {
        return res.status(422).json({ errors: errors.array() })
    }

};

These are validation type

• isLength()
• isEmail()
• isNumeric()
• contains(), check if value contains the specified value
• equals(), check if value equals the specified value
• isAlpha()
• isAlphanumeric()
• isAscii()
• isBase64()
• isBoolean()
• isCurrency()
• isDecimal()
• isEmpty()
• isFQDN(), is a fully qualified domain name?
• isFloat()
• isHash()
• isHexColor()
• isIP()
• isIn(), check if the value is in an array of allowed values
• isInt()
• isJSON()
• isLatLong()
• isLength()
• isLowercase()
• isMobilePhone()
• isNumeric()
• isPostalCode()
• isURL()
• isUppercase()
• isWhitelisted(), checks the input against a whitelist of allowed characters
• isAfter(), check if the entered date is after the one you pass
• isBefore(), check if the entered date is before the one you pass
• isISO8601()
• isRFC3339()