Add JSON Pointer support to JsonReader

This enhancement allows users to specify a JSON Pointer to extract
specific parts of a JSON document when reading. Key changes include:

- New get(String pointer) method in JsonReader class
- Updated JsonReaderTests with pointer-based extraction tests
- Added documentation for JSON Pointer usage in etl-pipeline.adoc

This feature enables more flexible parsing of complex JSON structures,
allowing users to easily target nested data for extraction.

spring-ai-core/src/main/java/org/springframework/ai/reader/JsonReader.java

@@ -103,4 +103,37 @@ public class JsonReader implements DocumentReader {
 		return new Document(content, metadata);
 	}
 
+	protected List<Document> get(JsonNode rootNode) {
+		if (rootNode.isArray()) {
+			return StreamSupport.stream(rootNode.spliterator(), true)
+				.map(jsonNode -> parseJsonNode(jsonNode, objectMapper))
+				.toList();
+		}
+		else {
+			return Collections.singletonList(parseJsonNode(rootNode, objectMapper));
+		}
+	}
+
+	/**
+	 * Retrieves documents from the JSON resource using a JSON Pointer.
+	 * @param pointer A JSON Pointer string (RFC 6901) to locate the desired element
+	 * @return A list of Documents parsed from the located JSON element
+	 * @throws RuntimeException if the JSON cannot be parsed or the pointer is invalid
+	 */
+	public List<Document> get(String pointer) {
+		try {
+			JsonNode rootNode = objectMapper.readTree(this.resource.getInputStream());
+			JsonNode targetNode = rootNode.at(pointer);
+
+			if (targetNode.isMissingNode()) {
+				throw new IllegalArgumentException("Invalid JSON Pointer: " + pointer);
+			}
+
+			return get(targetNode);
+		}
+		catch (IOException e) {
+			throw new RuntimeException("Error reading JSON resource", e);
+		}
+	}
+
 }

spring-ai-core/src/test/java/org/springframework/ai/reader/JsonReaderTests.java

@@ -28,11 +28,14 @@ import static org.assertj.core.api.Assertions.assertThat;
 @SpringBootTest
 public class JsonReaderTests {
 
+	@Value("classpath:person.json")
+	private Resource ObjectResource;
+
 	@Value("classpath:bikes.json")
 	private Resource arrayResource;
 
-	@Value("classpath:person.json")
-	private Resource ObjectResource;
+	@Value("classpath:events.json")
+	private Resource eventsResource;
 
 	@Test
 	void loadJsonArray() {
@@ -56,4 +59,26 @@ public class JsonReaderTests {
 		}
 	}
 
+	@Test
+	void loadJsonArrayFromPointer() {
+		assertThat(arrayResource).isNotNull();
+		JsonReader jsonReader = new JsonReader(eventsResource, "description");
+		List<Document> documents = jsonReader.get("/0/sessions");
+		assertThat(documents).isNotEmpty();
+		for (Document document : documents) {
+			assertThat(document.getContent()).isNotEmpty();
+			assertThat(document.getContent()).contains("Session");
+		}
+	}
+
+	@Test
+	void loadJsonObjectFromPointer() {
+		assertThat(ObjectResource).isNotNull();
+		JsonReader jsonReader = new JsonReader(ObjectResource, "name");
+		List<Document> documents = jsonReader.get("/store");
+		assertThat(documents).isNotEmpty();
+		assertThat(documents.size()).isEqualTo(1);
+		assertThat(documents.get(0).getContent()).contains("name: Bike Shop");
+	}
+
 }

spring-ai-core/src/test/resources/events.json

@@ -0,0 +1,15 @@
+[
+  {
+    "sessions": [
+      {
+        "description": "Session one"
+      },
+      {
+        "description": "Session two"
+      },
+      {
+        "description": "Session three"
+      }
+    ]
+  }
+]

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/etl-pipeline.adoc

@@ -154,6 +154,44 @@ The `JsonReader` processes JSON content as follows:
 ** It generates metadata using the provided `JsonMetadataGenerator` (or an empty one if not provided).
 ** It creates a `Document` object with the extracted content and metadata.
 
+
+==== Using JSON Pointers
+
+The `JsonReader` now supports retrieving specific parts of a JSON document using JSON Pointers. This feature allows you to easily extract nested data from complex JSON structures.
+
+===== The `get(String pointer)` method
+
+[source,java]
+----
+public List<Document> get(String pointer)
+----
+
+This method allows you to use a JSON Pointer to retrieve a specific part of the JSON document.
+
+====== Parameters
+
+* `pointer`: A JSON Pointer string (as defined in RFC 6901) to locate the desired element within the JSON structure.
+
+====== Return Value
+
+* Returns a `List<Document>` containing the documents parsed from the JSON element located by the pointer.
+
+====== Behavior
+
+* The method uses the provided JSON Pointer to navigate to a specific location in the JSON structure.
+* If the pointer is valid and points to an existing element:
+** For a JSON object: it returns a list with a single Document.
+** For a JSON array: it returns a list of Documents, one for each element in the array.
+* If the pointer is invalid or points to a non-existent element, it throws an `IllegalArgumentException`.
+
+====== Example
+
+[source,java]
+----
+JsonReader jsonReader = new JsonReader(resource, "description");
+List<Document> documents = jsonReader.get("/store/books/0");
+----
+
 ==== Example JSON Structure
 
 [source,json]