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Form Validator

Class FormValidator is a helper class to validate incoming requests.

FormValidator methods

There are several methods in FormValidator:

  • validate(request: Dict[str, Any], rules: Dict[str, Any], check_missed: bool = False, check_unknown: bool = True, templates: Dict[str, str] = {}) - the main action method, I will describe arguments in the section below. It returns itself (FormValidation instance)
  • failed() - returns True if a validation failed, else False
  • get_errors() - returns list of all validation errors, if there are no errors, it returns empty list ([])
  • get_messages() - returns dictionary with validation errors related to keys in provided rules, if rule doesn't have errors, then value of key will be None.

FormValidator validate arguments

Method validate has several arguments:

  • request: Dict[str, Any] - data received from form. Must be a dictionary.
  • rules: Dict[str, Any] - it is a dictionary where keys must match with keys of request, values of this dictionary are validation rules.
  • check_missed: bool = False - check if request doesn't have one or more keys which are available in rules. If False all missed keys have None as a value, else keys treated as failed and have this error message - "Item key_name must be present".
  • check_unknown: bool = True - check if some addition keys appeared in request which are not present in rules. If True addition key appears in messages - _unknown_.
  • templates: Dict[str, str] = {} - dictionary of templates which must be applied to rule exceptions, here are more details.

Examples of usage

Successful validation

from respect_validation import FormValidator as fv, Validator as v

# rules are the same for all examples below
rules = {
    "username": v.stringType().alnum().noWhitespace().length(4, 64),
    "email": v.optional(v.email()),
    "password": v.stringType().length(8, 64)
}

user_data = {
    "username": "gurkin33",
    "email": "gurkin33@mail.com",
    "password": "123123123",
}

form_validation = fv()
form_validation.validate(request=user_data, rules=rules)

print(form_validation.failed())
print(form_validation.get_messages())
print(form_validation.get_errors())
Output 
# form_validation.failed()
False

# form_validation.get_messages()
{'_unknown_': None, 'username': None, 'email': None, 'password': None}

# form_validation.get_errors()
[]

Unexpected field in request

user_data = {
    "username": "gurkin33",
    "email": "gurkin33@mail.com",
    "password": "123123123",
    "personal_id": "123123123",
}

form_validation = fv()
form_validation.validate(request=user_data, rules=rules)

print(form_validation.failed())
print(form_validation.get_messages())
print(form_validation.get_errors())
Output 
# form_validation.failed()
True

# form_validation.get_messages()
{'_unknown_': ['Unknown field personal_id'], 'username': None, 'email': None, 'password': None}

# form_validation.get_errors()
[{'_unknown_': ['Unknown field personal_id']}]

Missed field in request (with check)

user_data = {
    "username": "gurkin33",
    "email": "gurkin33@mail.com",
}

form_validation = fv()
form_validation.validate(request=user_data, rules=rules, check_missed=True)

print(form_validation.failed())
print(form_validation.get_messages())
print(form_validation.get_errors())
Output 
# form_validation.failed()
True

# form_validation.get_messages()
{'_unknown_': None, 'username': None, 'email': None, 'password': ['Item password must be present']}

# form_validation.get_errors()
[{'password': ['Item password must be present']}]

Now we can go to integration with simple flask app.