JSON-LD Lint

This package contains the core JSON-LD lint engine written in typescript its primary dependencies are

• vscode-json-languageservice for JSON document parsing
• jsonld.js for certain JSON-LD operations

Syntax Errors

The following defines the different types of syntax errors the processing engine detects, if a syntax error is encountered subsequent processing of the document terminates.

Unexpected JSON-LD Keyword Value Type

Rule - jsonld-lint/unexpected-json-value-type

A result of this type will be returned when an unexpected value type for a JSON-LD keyword is encountered.

Example - Invalid as the expected JSON value types for @context are string, array or object.

{
  "@context": false
}

Unexpected JSON-LD Keyword Value

Rule - jsonld-lint/unexpected-json-value

A result of this type will be returned when an unexpected value for a JSON-LD keyword is encountered.

Example - Invalid as the expected values for @version are 1, 1.0 and 1.1.

{
  "@version": 25
}

Unexpected use of JSON-LD keyword

Rule - jsonld-lint/unexpected-use-of-jsonld-keyword

A result of this type will be returned when a JSON-LD keyword is used in an unexpected way.

Example - Invalid as @base is not valid inside a node object only in a local context definition.

{
  "@base": "https://example.com"
}

Duplicate key in JSON object

Rule - jsonld-lint/duplicate-json-key

A result of this type will be return when an object/map within a JSON-LD document is encountered that features duplicate property keys, which is illegal in JSON-LD.

Example - Invalid as the test property key is repeated.

{
  "test": true,
  "test": false
}

Duplicate aliased JSON-LD keyword

Rule - jsonld-lint/duplicate-alias-jsonld-keyword

A result of this type will be return when an object/map within a JSON-LD document has the aliased equivalent properties both featured in the same JSON object.

Example - Invalid as id is an alias of the JSON-LD keyword @id.

{
  "id": "test-id",
  "@id": "test-id"
}

Invalid JSON-LD keyword as term value

Rule - jsonld-lint/invalid-jsonld-keyword-as-term-value

A result of this type will be returned when a JSON value type of string is encountered where the value matches a JSON-LD keyword being used in an invalid manner.

Example - Invalid when a JSON property has a string value of @context because it is a JSON-LD keyword, @type is the only JSON-LD keyword allowed.

{
  "property": "@context"
}

Linting Rules

The following defines the different types of linting results the processing engine detects.

Unrecognized JSON-LD keyword

Rule - jsonld-lint/unrecognized-jsonld-keyword

JSON-LD keywords use the common pattern of featuring the @ as a prefix, to ensure preservation of the namespace and allow future versions of JSON-LD to define new terms, developers are encourage to not feature JSON properties where the key is prefixed with an @ symbol and it is not defined by JSON-LD.

Example - The JSON key of @this-is-a-test matches the convention of being a JSON-LD term but is not a JSON-LD term.

{
  "@this-is-a-test": true
}

Un-mapped Term

Rule - jsonld-lint/unmapped-term

A result of this type will be returned when expansion of a term fails. This is usually due to the term not being documented in the documents context.

Example - The term undefinedTerm is not defined in the documents context, hence will be reported as an un-mapped term.

{
  "@context": {
    "definedTerm": "https://example.com/definedTerm"
  },
  "definedTerm": "good",
  "undefinedTerm": "bad"
}

Empty JSON Property Key

Rule - jsonld-lint/empty-json-property-key

A result of this type will be returned when a JSON property key is encountered which is an empty string

Example - The JSON object contains an empty string as the key for one of the JSON properties

{
  "@context": {},
  "": false
}