Validation

Framework to validate dictionaries.

Usage

The simplest usage form is as follow:

# Create a validation schema, here it tests that the entry "test" validates into an integer
schema = Validation({"test": "integer"})
# Test the schema on a dictionary, a result is returned.
# If the schema does not validate, it throws (by default, this behavior can be configured)
result = schema.validate({"test": "2"})
# The result can be used to access the parsed values
result.values == {"test": 2}
# The result can also be evaluated to bool to check if the result is valid. Note that in this
# example, this is irrelevant as the validate function is configured to throw by default.

It also works similarly for lists:

# Create a validation schema, here it tests that a list has one element and is an integer.
schema = Validation(["integer"])
result = schema.validate(["2"])
# The result can be used to access the parsed values
result.values == [2]

Noexcept

The validate function can be used to not throw if the schema does not validate. This is done as follow:

result = schema.validate({"test": "2"}, output="return")
if not result:
    # Handle error here!

Constraints

The following constraints are available:

Name	Extends	Underlying	Documentation
boolean		bool	Check that it represents a boolean (true/false).
float	min(i), max(i)	float	Check that it represents a floating point number.
integer	min(i), max(i)	int	Check that it represents an integer number.
mandatory			Ensure that the entry is present.
string	min(i), max(i)	str	Check that it represents a string.

Custom constraints

It is possible to enrich the validation by adding custom constraints. The new constraint must inherit from Constraint.

The validation process is performed in 2 different steps:

install the constraint. This step checks the format on the constraint itself, for example, if we use min constraint, it ensures that it contains a single integer argument: min(12) for example. This step is executed during the object construction phase.
check the constraint. This will do check on the value itself, therefore this is performed during the validate function call. In addition, during this step, the user can perform the following operations: - Introduce extra temporary constraint to this entry, that will be validated afterward. - Set the underlying value, this can be accessed from the result.