Added option to generate a message with a function callback

Author: larsvankleef

README.md

@@ -1,8 +1,8 @@
 # Validate
 
-> **This package is build for node and can not be used into the browser yet**
+> A simple validation util for react or vue. It works in nodejs to.
 
-```js
+```js example
 const { validate, email, length, required } = require('validate')
 
 const rules = {
@@ -11,17 +11,23 @@ const rules = {
       validator: value => {
         return length(value, { max: 75 }) && email(value)
       },
-      message: 'The given email address is invalid',
+      message: ({ value }) => {
+        return `${value} is not valid email address or the length is to high.`
+      },
     },
     password: {
       validator: value => {
         return length(value, { min: 4, max: 18 })
       },
+      message: ({ value, field }) => {
+        return `The length of your password is tho short it must be between 4 and 18 charters long.`
+      },
     },
     subscription: {
       validator: value => {
         return required(value)
       },
+      message: `Please choose a subscription type`,
     },
   },
 }
@@ -30,3 +36,10 @@ const { valid } = validate(fields, {
   rules,
 })
 ```
+
+## Good the now.
+
+No sanitizing has been done on the return value in the message function. It is your job
+to use a library to achieve this.
+
+[dompurify](https://www.npmjs.com/package/dompurify)

jest.config.js

@@ -19,6 +19,7 @@
     "jest": "^26.2.2",
     "prettier": "^2.0.5",
     "rollup": "^2.23.1",
-    "rollup-plugin-filesize": "^9.0.2"
+    "rollup-plugin-filesize": "^9.0.2",
+    "@types/jest": "^26.0.10"
   }
 }

package.json

@@ -1,4 +1,4 @@
-const { validate, email, length, required } = require('../validate')
+const { validate, email, length, required } = require('../index')
 
 const defaultRules = {
   fields: {
@@ -29,7 +29,7 @@ it('initializes', () => {
 
 it('returns invalid when there are no rules', () => {
   const fields = {
-    password: 'homepage'
+    password: 'homepage',
   }
   const rules = {}
 
@@ -115,3 +115,37 @@ it('validates to false when one one of the validation rules returns false', () =
     ]
   `)
 })
+
+it('supports the message object to be a function and then calls it with the field and the value', () => {
+  const email = '[email protected]'
+  const validator = jest.fn(() => false)
+  const message = jest.fn(
+    ({ field, value }) => `The field ${field} is incorrect with value ${value}`,
+  )
+  const passwordMessage = 'it works with a string to'
+
+  const fields = { email, password: 'password', subscription: true }
+  const rules = {
+    fields: {
+      email: { validator, message },
+      password: { validator, message: passwordMessage },
+      subscription: { validator, message: () => undefined },
+    },
+  }
+
+  const { valid, results } = validate(fields, { rules })
+
+  expect(message).toBeCalledTimes(1)
+  expect(message).toBeCalledWith({ field: 'email', value: email })
+  expect(valid).toEqual(false)
+
+  expect(results.find(item => item.field === 'email').message).toEqual(
+    `The field email is incorrect with value ${email}`,
+  )
+  expect(results.find(item => item.field === 'password').message).toEqual(
+    passwordMessage,
+  )
+  expect(results.find(item => item.field === 'subscription').message).toEqual(
+    "Validation failed for field 'subscription'",
+  )
+})

src/__tests__/validate.test.js

@@ -12,13 +12,19 @@ function validate(fields, { rules }) {
     if (rule.validator(value)) {
       checked.push({ field, value: fields[field], valid: true, message: '' })
     } else {
+      const value = fields[field]
+
+      const message = compileTheMessage({
+        message: rules.fields[field].message,
+        value,
+        field,
+      })
+
       checked.push({
         field,
-        value: fields[field],
+        value,
         valid: false,
-        message:
-          rules.fields[field].message ||
-          `Validation failed for field '${field}'`,
+        message,
       })
     }
   })
@@ -29,6 +35,20 @@ function validate(fields, { rules }) {
   }
 }
 
+function compileTheMessage({ message, value, field }) {
+  const defaultOutputString = `Validation failed for field '${field}'`
+
+  if (!message) return defaultOutputString
+  if (typeof message === 'function') {
+    const output = message({ field, value })
+
+    if (!output) return defaultOutputString
+    return output
+  }
+
+  return message
+}
+
 module.exports = {
   validate,
   ...require('./validation/index.js'),