Struct level validations

Validations can also be registered at the struct level when field level validations
don’t make much sense. This can also be used to solve cross-field validation elegantly.
Additionally, it can be combined with tag validations. Struct Level validations run after
the structs tag validations.

Example requests

  1. # Validation errors are generated for struct tags as well as at the struct level
  2. $ curl -s -X POST http://localhost:8085/user \
  3.     -H 'content-type: application/json' \
  4.     -d '{}' | jq
  5. {
  6.   "error": "Key: 'User.Email' Error:Field validation for 'Email' failed on the 'required' tag\nKey: 'User.FirstName' Error:Field validation for 'FirstName' failed on the 'fnameorlname' tag\nKey: 'User.LastName' Error:Field validation for 'LastName' failed on the 'fnameorlname' tag",
  7.   "message": "User validation failed!"
  8. }
  10. # Validation fails at the struct level because neither first name nor last name are present
  11. $ curl -s -X POST http://localhost:8085/user \
  12.     -H 'content-type: application/json' \
  13.     -d '{"email": "george@vandaley.com"}' | jq
  14. {
  15.   "error": "Key: 'User.FirstName' Error:Field validation for 'FirstName' failed on the 'fnameorlname' tag\nKey: 'User.LastName' Error:Field validation for 'LastName' failed on the 'fnameorlname' tag",
  16.   "message": "User validation failed!"
  17. }
  19. # No validation errors when either first name or last name is present
  20. $ curl -X POST http://localhost:8085/user \
  21.     -H 'content-type: application/json' \
  22.     -d '{"fname": "George", "email": "george@vandaley.com"}'
  23. {"message":"User validation successful."}
  25. $ curl -X POST http://localhost:8085/user \
  26.     -H 'content-type: application/json' \
  27.     -d '{"lname": "Contanza", "email": "george@vandaley.com"}'
  28. {"message":"User validation successful."}
  30. $ curl -X POST http://localhost:8085/user \
  31.     -H 'content-type: application/json' \
  32.     -d '{"fname": "George", "lname": "Costanza", "email": "george@vandaley.com"}'
  33. {"message":"User validation successful."}