jsonschema

The jsonschema R package validates ‘JSON’ (JavaScript Object Notation) files against a specified JSON schema. Most functionality comes directly from Patrick Boettcher’s ‘json-schema-validator’ C++ library, along with Neils Lohmann’s ‘Modern JSON for C++’ library. Both of these libraries are included here.

The ‘json-schema-validator’ library, and hence this package, validates against JSON Schema Draft 7.

Example

This example is modified from the pboettch/json-schema-validator/ README. The schema illustrates the general structure of JSON schemas:

schema <- '{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "title": "A person",
    "properties": {
        "id": {
            "description": "Unique identifier",
            "type": "integer"
        },
        "date": {
            "type": "string",
            "format": "date"
        },
        "name": {
            "description": "Name",
            "type": "string"
        },
        "age": {
            "description": "Age of the person",
            "type": "number",
            "minimum": 2,
            "maximum": 200
        }
    },
    "required": [
                 "id",
                 "date",
                 "name",
                 "age"
                 ],
    "type": "object"
}'

That repository then provides the following examples of JSON input to validate against that schema:

person_bad <- '{
    "id": "nope",
    "date": "2022-02",
    "age": 42
}'
person_good <- '{
    "id": 1,
    "date": "2022-02-02",
    "name": "Albert",
    "age": 42
}'

This package works exclusively with locally-stored files. The following lines save those three items to local files.

writeLines (schema, "schema.json")
writeLines (person_bad, "person_bad.json")
writeLines (person_good, "person_good.json")

The JSON files can then be validated by loading the package and running its single function:

library (jsonschema)
jsonschema_validate ("schema.json", "person_good.json") # no output
jsonschema_validate ("schema.json", "person_bad.json")

## JSON Error: '': required property 'name' not found in object
## JSON Error: '/date': format-checking failed: 2022-02 is not a date string according to RFC 3339.
## JSON Error: '/id': unexpected instance type

The results can be captured in a data.frame object like this:

x <- jsonschema_validate ("schema.json", "person_bad.json", quiet = TRUE)
print (x)

##      id                                                 msg expected_type
## 1              required property 'name' not found in object
## 2 /date 2022-02 is not a date string according to RFC 3339.        string
## 3   /id                            unexpected instance type       integer

Prior Art

The ‘jsonvalidate’ package also validates JSON files against schemas, through wrapping two JavaScript libraries.

Code of Conduct

Please note that this package is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.