Validation

Framework to validate dictionaries.

Usage

The simplest usage form is as follows:

# 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 follows:

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 the 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 a 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 an extra temporary constraint to this entry, that will be validated afterward. - Set the underlying value, this can be accessed from the result.