Build an S7 class from a JSON Schema

The read direction of S7_to_JSONSchema: reads each property's PropertySpec back out of the schema and assembles a live S7 class whose properties carry the same types, bounds, enums, containers, and validators as the class the schema was generated from.

Usage

JSONSchema_to_S7(
  schema,
  defaults = NULL,
  refs = NULL,
  name = NULL,
  package = NULL,
  authoring = NULL,
  declarations = NULL,
  schemas = NULL,
  decode_reference = NULL,
  parent = NULL,
  policies = NULL
)

Arguments

schema

Named list: A JSON Schema, as produced by S7_to_JSONSchema or parsed from the published tree with jsonlite::fromJSON(simplifyVector = FALSE).

defaults

Optional named list: Format version 1 defaults artifact, or explicit property declaration values for an independently supplied schema.

refs

Optional named list: Property name to S7 class, for properties published as a $ref to another schema.

name

Optional Character: Class name. Defaults to the schema title.

package

Optional Character: Package name recorded on the class.

authoring

Optional named list: Property name to logical authorship policy, from the separate authoring artifact under this schema's $id.

declarations

Optional List: Declaration descriptors keyed by schema pointer.

schemas

Optional List: Complete parsed schema graph keyed by canonical ID. Used with a format version 1 artifact to reconstruct typed references without source classes.

decode_reference

Optional Function: Reference decoder for a custom artifact graph.

parent

Optional S7 class: Reconstructed parent type.

policies

Optional List: Serialized input policy descriptors.

Value

S7 class.

Details

Defaults are supplied in a separate versioned artifact keyed by schema $id. The published schemas carry no default keywords. Absent declaration defaults remain absent; constructing a non-nullable property without a default requires a value.

Properties holding a nested config are published as a $ref to that config's own schema. Supply the parsed graph through schemas and the format version 1 artifact through defaults to reconstruct these references. Independently supplied S7 reference classes can be passed through refs. Reconstructed constructors use declaration defaults; input resolution policies remain separate metadata on the class.

Author

EDG

Examples

# A schema as `S7_to_JSONSchema()` emits it: standard keywords carry the
# bounds, `x-rtemis` carries the leaf type.
schema <- list(
  title = "Demo",
  properties = list(
    k = list(
      type = "integer",
      minimum = 1L,
      maximum = 10L,
      description = "Number of components.",
      `x-rtemis` = list(type = "integer")
    )
  )
)
Demo <- JSONSchema_to_S7(schema, defaults = list(k = 2L))
Demo()@k

#> [1] 2

Demo(k = 5L)@k

#> [1] 5

# The reconstructed class enforces the schema's bounds.
tryCatch(Demo(k = 99L), error = conditionMessage)

#> [1] "<Demo> object properties are invalid:\n- @k must be <= 10."