Inject a JSON-LD @context

JSON-LD property names only become RDF terms when a context maps them to IRIs. If the input JSON has no @context, and the source cannot provide one through an HTTP Link header, pass the context with expandContext.

Use this for JSON already loaded from a file, queue, database, or API client:

1. Load or receive the plain JSON document.
2. Define the context your application wants to apply.
3. Pass that context in the operation options as expandContext.
4. Run jsonld.expand() or another API that expands internally.

PyLD processes expandContext before expansion. If the document also has its own @context, that document context is processed later and can refine or override term definitions for the document body.

Example inject_context.py

import json

from pyld import jsonld

doc = {
    "name": "Ada Lovelace",
    "homepage": "https://example.com/ada",
}
context = {
    "name": "http://schema.org/name",
    "homepage": {"@id": "http://schema.org/url", "@type": "@id"},
}

expanded = jsonld.expand(doc, {"expandContext": context})

print(json.dumps(expanded, indent=2))

Output

[
  {
    "http://schema.org/url": [
      {
        "@id": "https://example.com/ada"
      }
    ],
    "http://schema.org/name": [
      {
        "@value": "Ada Lovelace"
      }
    ]
  }
]

The same option works with APIs that expand internally, including jsonld.compact(), jsonld.flatten(), and jsonld.frame():

Example inject_context_compact.py

import json

from pyld import jsonld

doc = {
    "name": "Ada Lovelace",
    "homepage": "https://example.com/ada",
}
source_context = {
    "name": "http://schema.org/name",
    "homepage": {"@id": "http://schema.org/url", "@type": "@id"},
}
output_context = {
    "name": "http://schema.org/name",
    "url": {"@id": "http://schema.org/url", "@type": "@id"},
}

compacted = jsonld.compact(
    doc,
    output_context,
    {"expandContext": source_context},
)

print(json.dumps(compacted, indent=2))

Output

{
  "@context": {
    "name": "http://schema.org/name",
    "url": {
      "@id": "http://schema.org/url",
      "@type": "@id"
    }
  },
  "name": "Ada Lovelace",
  "url": "https://example.com/ada"
}

Use an in-document @context when you control the JSON. Use expandContext when the context is application policy or transport metadata.