Add the ability to pass a custom identifierIssuer to to_rdf

Author: mielvds

CHANGELOG.md

@@ -6,6 +6,9 @@
 - `pyld.FileDocumentLoader`: a document loader for local `file:` URLs with optional root confinement.
 - `pyld.SchemeDirectedDocumentLoader`: a document loader that dispatches URL
   strings to per-scheme loaders.
+- `jsonld.to_rdf()` now accepts an `identifierIssuer` option with an
+  `IdentifierIssuer` instance for blank node identifiers. Defaults to `IdentifierIssuer('_:b')`, 
+  which preserves the previous behaviour.
 
 ## 3.2.0 - 2026-08-17
 

README.md

@@ -65,6 +65,7 @@ Here are some quick examples to get started:
 
 ```python
 from pyld import jsonld
+from pyld.identifier_issuer import IdentifierIssuer
 import json
 
 doc = {
@@ -126,6 +127,12 @@ normalized = jsonld.normalize(
     doc, {'algorithm': 'URDNA2015', 'format': 'application/n-quads'})
 # normalized is a string that is a canonical representation of the document
 # that can be used for hashing, comparison, etc.
+
+# convert a document to RDF with a custom blank node issuer
+issuer = IdentifierIssuer('_:doc')
+rdf = jsonld.to_rdf(
+    doc,
+    {'identifierIssuer': issuer, 'format': 'application/n-quads'})
 ```
 
 ## Features & conformance
@@ -421,4 +428,4 @@ See [`LICENSE`](./LICENSE) file for details.
 The PyLD library is maintained by [Miel Vander
 Sande](https://github.com/mielvds), [Anatoly
 Scherbakov](https://github.com/anatoly-scherbakov) and [Digital
-Bazaar](https://github.com/digitalbazaar) (Original authors of `PyLD`).
+Bazaar](https://github.com/digitalbazaar) (Original authors of `PyLD`).

docs/reference/to_rdf.md

@@ -12,6 +12,9 @@
       show_bases: false
       heading_level: 3
 
+Pass an `IdentifierIssuer` instance as the `identifierIssuer` option to control
+blank node identifiers generated during RDF conversion.
+
 ## Example
 
 {{ example('to_rdf.py') }}

lib/pyld/jsonld.py

@@ -1007,6 +1007,8 @@ def to_rdf(self, input_, options):
             to produce only standard RDF (default: false).
           [documentLoader(url, options)] the document loader
             (default: _default_document_loader).
+          [identifierIssuer] an IdentifierIssuer instance to use for blank node
+            identifiers (default: IdentifierIssuer('_:b')).
           [rdfDirection] Either 'i18n-datatype' or 'compound-literal'
             (default: None).
 
@@ -1023,6 +1025,7 @@ def to_rdf(self, input_, options):
         )
         options.setdefault('extractAllScripts', True)
         options.setdefault('processingMode', 'json-ld-1.1')
+        options.setdefault('identifierIssuer', IdentifierIssuer('_:b'))
 
         try:
             # expand input
@@ -1033,7 +1036,7 @@ def to_rdf(self, input_, options):
             ) from cause
 
         # create node map for default graph (and any named graphs)
-        issuer = IdentifierIssuer('_:b')
+        issuer = options['identifierIssuer']
         node_map = {'@default': {}}
         self._create_node_map(expanded, node_map, '@default', issuer)
         # output RDF dataset

lib/pyld/options.py

@@ -9,6 +9,7 @@
 from typing import Any, Literal, TypedDict
 
 from .documentloader.base import DocumentLoader, RemoteDocument
+from .identifier_issuer import IdentifierIssuer
 
 ContextObject = dict[str, Any]
 Context = str | ContextObject | list[str | ContextObject]
@@ -175,6 +176,9 @@ class ToRdfOptions(ProcessingOptions, total=False):
     produceGeneralizedRdf: bool
     """`True` to output generalized RDF, `False` to produce only standard RDF (default: `False`)."""
 
+    identifierIssuer: IdentifierIssuer
+    """An identifier issuer to use for blank node identifiers (default: `IdentifierIssuer('_:b')`)."""
+
     rdfDirection: Literal['i18n-datatype']
     """Only `i18n-datatype` supported."""
 

tests/test_jsonld.py

@@ -1,6 +1,7 @@
 import pytest
 
 import pyld.jsonld as jsonld
+from pyld.identifier_issuer import IdentifierIssuer
 
 
 def raise_this(value):
@@ -998,6 +999,24 @@ def test_large_integer_to_rdf_double_conversion_processing_mode(self):
             '^^<http://www.w3.org/2001/XMLSchema#integer> .\n'
         )
 
+    def test_to_rdf_uses_identifier_issuer_option(self):
+        input = {'http://example.org/p': [{'@list': ['a', 'b']}]}
+        issuer = IdentifierIssuer('_:custom')
+
+        nquads = jsonld.to_rdf(
+            input,
+            options={'format': 'application/n-quads', 'identifierIssuer': issuer},
+        )
+
+        assert nquads == (
+            '_:custom0 <http://example.org/p> _:custom1 .\n'
+            '_:custom1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#first> "a" .\n'
+            '_:custom1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#rest> _:custom2 .\n'
+            '_:custom2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#first> "b" .\n'
+            '_:custom2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#rest> '
+            '<http://www.w3.org/1999/02/22-rdf-syntax-ns#nil> .\n'
+        )
+
     def test_compound_literal_direction_without_language(self):
         """
         Values with @direction should become compound literals during to_rdf