google.appengine.api.validation.Validator

Validator base class.

Inherits From: expected_type

google.appengine.api.validation.Validator(
    default=None
)

Though any callable can be used as a validator, this class encapsulates the case when a specific validator needs to hold a particular state or configuration.

To implement Validator sub-class, override the validate method.

This class is permitted to change the ultimate value that is set to the attribute if there is a reasonable way to perform the conversion.

default Default assignment is made during initialization and will not pass through validation.

Child Classes

class expected_type

Methods

CheckFieldInitialized

View source

CheckFieldInitialized(
    value, key, obj
)

Check for missing fields or conflicts between fields.

Default behavior performs a simple None-check, but this can be overridden. If the intent is to allow optional fields, then use the Optional validator instead.

Args
value Value to validate.
key Name of the field being validated.
obj The object to validate against.

Raises
ValidationError When there are missing or conflicting fields.

GetWarnings

View source

GetWarnings(
    value, key, obj
)

Return any warnings on this attribute.

Validates the value with an eye towards things that aren't fatal problems.

Args
value Value to validate.
key Name of the field being validated.
obj The object to validate against.

Returns
A list of tuples (context, warning) where

  • Context is the field (or dotted field path, if a sub-field)
  • Warning is the string warning text

ToValue

View source

ToValue(
    value
)

Convert value to a simplified collection or basic type.

Subclasses of Validator should override this method when the dumped representation of value is not a simple <type>(value) (e.g., a regex).

Args
value An object of the same type that was returned from Validate().

Returns
An instance of a builtin type (e.g., int, str, dict, etc). By default it returns value unmodified.

Validate

View source

Validate(
    value, key='???'
)

Validate this field. Override to customize subclass behavior.

Args
value Value to validate.
key Name of the field being validated.

Returns
Value if value is valid, or a valid representation of value.

__call__

View source

__call__(
    value, key='???'
)

Main interface to validator is call mechanism.