Input validation

When a validation error is encountered, the api will return the status code 400 and in the body it will detail for each field the shared error encountered.
Each endpoint may have errors other than generic errors. These will be explained at each endpoint.
The error text in errorMessage will only be used for debugging and will not be displayed to the user. It is the programmer's duty to display specific error texts depending on the context / language, etc.
Errors that have the extra attribute will also contain an errorExtraValue key that will contain the referenced value.

Output example

[
  {
    "errorField": "uaTos",
    "errorCode": 1,
    "errorMessage": "The field is required."
  },
  {
    "errorField": "uaPrivacy",
    "errorCode": 8,
    "errorMessage": "The field can not exceed 1 characters in length.",
    "errorExtraValue": 1
  },
  {
    "errorCode": 99,
    "errorMessage": "Something went wrong."
  }
]

Code	Name	Message	Validation
1	required	The field is required.	No
2	isset	The field must be present.	No
3	valid_email	The field must contain a valid email address.	No
4	valid_emails	The field must contain all valid email addresses.	No
5	valid_url	The field must contain a valid URL.	No
6	valid_ip	The field must contain a valid IPv4 address.	No
7	min_length	The field must be at least %% characters in length.	Yes
8	max_length	The field can not exceed %% characters in length.	Yes
9	exact_length	The field field must be exactly %% characters in length.	Yes
10	alpha	The field may only contain alphabetical characters.	No
11	alpha_numeric	The field may only contain alpha-numeric characters.	No
13	numeric	The field must contain only numbers.	No
14	is_numeric	The field must contain only numeric characters.	No
15	integer	The field must contain an integer.	No
16	regex_match	The field is not in the correct format.	No
17	matches	The field does not match the %% field.	Yes
18	is_unique	The field must contain a unique value.	No
19	is_natural	The field must contain only positive numbers.	No
20	is_natural_no_zero	The field must contain a number greater than zero.	No
21	decimal	The field must contain a decimal number.	No
22	less_than	The field must contain a number less than %%.	Yes
23	greater_than	The field must contain a number greater than %%.	Yes
24	rfc_date	The field must contain a valid date. Ex: 2018-06-22	No
25	rfc_datetime	The field must contain a valid time. Ex: 2018-06-22 23:44:02	No
26	values	The field must contain a one of the following values: %%.	Yes
27	valid_phone	The field must contain a valid phone number. (+4012345789)	No
28	is_absent	The field must be absent.	No
29	invalid_value	The field must be one of the allowed values.	No
99	generic	Generic error. No ideea what happened.	No