/ds-validation-3

Validation - Exercise #3 - Custom Error Messages & Outsourcing

In this exercise we are going to make our validation messages a bit more user friendly and self-explanatory. Instead of just telling the user that an input is invalid we want to provide detailed information what exactly is wrong and how to correct it.

Setup custom error messages

Continue working on your previous exercise code OR copy your previous server.js file to here and repeat the installation of express and express-validator.

  • Adapt the field error messages in your check functions
    • Give more explanatory validation error messages to the user
      • either use check("field", "<errMessage>") or check("field").withMessage("<errMessage>")

Setup validation for specific sources only

  • Import additionally the "body" function from the express validator package
  • Replace the check() calls to validate your form body fields by calls to body()
  • Test if your form submit still works

Outsource validators into middleware

  • Bundle the check routes to an array
  • Outsource the array to a variable outside the route
  • Add a middleware for your POST route and attach the array as middleware
    • This will cause that on each call to the POST register route this array / chain of middleware function checks will run FIRST
    • Do not forget to call next() within the middleware function

BONUS TASK

  • Create a new GET route /users/:id

  • Create an array of three users within that route: let users = [ {id: 1, user: "Leandro"}, {id: 2, user: "Leon"}, {id: 3, user: "Rob"}, ]

  • If the user provides the param ID: deliver back the user with that ID as response

  • If no param ID given: deliver back ALL users

  • If a query param "search" was given

    • search for this user an return it back
    • also allow partly searches, e.g. "Le" should deliver "Leandro" AND "Leon"
    • also allow case insensitive search, e.g. "ro" should deliver "Leandro" AND "Rob"

  • Add field validation

    • Check for param ID and assure, if it is given, it is an integer
    • Validate the field "search" in the query string only. Use the query() check function for that
    • We also want that the search term is optional and does not need to be stated
      • use the .optional({checkFalsy: true}) function to make the search term optinal .optional()