fluffy (version 1.0.0)

Schema: Schema

Description

Create a Schema object that defines and validates a schema for the future validation of R objects using a Validator.

Usage

Schema(schema, registry = Registry(), error = FALSE, ...)
is.Schema(x)

Value

A Schema S7 object.

Arguments

schema

Non-empty list defining the schema. Each leaf element to be validated must be named with rules that are registered in the schema rule registry (see Registry and add_rule). Named elements must be unique at a given level of the list.

registry

Object of class Registry containing the schema and validator rules to use for schema validation.

error

Single logical value. If TRUE, the constructor throws an error when the schema is invalid.

...

Named arguments passed to internal error message formatting: max_depth, max_width, max_rows, and UTF8 which control the truncation and printing of the error message when the schema validation fails. max_* arguments accept integerish scalar values, and UTF8 accepts a single logical value. Unnamed arguments or named arguments other than the above will be ignored.

x

Object to be tested.

Additional properties

@schema

The input schema list, with nodes reordered to match the order of the rules in the registry, and any strings converted to functions where applicable.

@errors

(Read-only) A list mirroring the schema structure, with NULL for valid rules and character error messages for invalid rules.

@Registry

An object of class Registry containing the schema and validator rules used for validation.

@.schema_cache

(Read-only) An environment for caching schema validation results. Used to avoid redundant validation.

@error

Boolean; whether to error on invalid schemas.

@error_print_opts

A list of options for error message printing when error = TRUE. These options are also used by the Validator class that ingests the Schema. Defaults are

• max_depth = 10L

• max_width = getOption("width")

• max_rows = 30L

• UTF8 = l10n_info()[["UTF-8"]]

@valid

(Read-only) Boolean; TRUE if schema is valid, FALSE otherwise.

Details

The Schema class defines the structure and rules for validating data using a Validator. It ingests the input schema list and then reorders and validates the schema according to the Registry. The resulting @schema property defines the validation behaviour and data matching.

Each element of the input list represents a field with named rules (e.g., 'type', 'required', 'min_val') that are checked against the schema rule registry. Cross rules (e.g., 'min_val_larger_than_max_val', where 'min_val' < 'max_val') are also evaluated when all constituent rules pass individually. See the Registry class for details.

The schema is re-evaluated upon any change to the schema properties, with the @valid property indicating whether the schema is valid (all rules pass) or invalid (any rule fails). If invalid, when passed to a Validator the validation will fail immediately.

For full details see the vignettes on builtin rules, data validation, and adding custom rules.

See Also

add_rule for adding rules to a Registry. Validator for validating data against a Schema.

Examples

# A valid schema
s <- Schema(list(
  name = list(type = "character", required = TRUE),
  age = list(type = "numeric", min_val = 0, max_val = 150)
))
s@valid # TRUE

# An invalid schema (type must be a string)
s <- Schema(list(name = list(type = 123)))
s@valid # FALSE
s@errors # error message

# To error on invalid schema
try(Schema(list(name = list(type = 123)), error = TRUE))