Add JsonOutputParser

spring-ai-core/src/main/java/org/springframework/ai/parser/AbstractMessageConverterOutputParser.java

@@ -0,0 +1,17 @@
+package org.springframework.ai.parser;
+
+import org.springframework.messaging.converter.MessageConverter;
+
+public abstract class AbstractMessageConverterOutputParser implements OutputParser<Object> {
+
+	private MessageConverter messageConverter;
+
+	public AbstractMessageConverterOutputParser(MessageConverter messageConverter) {
+		this.messageConverter = messageConverter;
+	}
+
+	public MessageConverter getMessageConverter() {
+		return messageConverter;
+	}
+
+}

spring-ai-core/src/main/java/org/springframework/ai/parser/JsonOutputParser.java

@@ -0,0 +1,38 @@
+package org.springframework.ai.parser;
+
+import org.springframework.messaging.Message;
+import org.springframework.messaging.converter.MappingJackson2MessageConverter;
+import org.springframework.messaging.converter.MessageConverter;
+import org.springframework.messaging.support.MessageBuilder;
+
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Uses Jackson
+ */
+public class JsonOutputParser extends AbstractMessageConverterOutputParser {
+
+	private Class dataType;
+
+	public JsonOutputParser(Class dataType) {
+		super(new MappingJackson2MessageConverter());
+		this.dataType = dataType;
+	}
+
+	@Override
+	public Object parse(String text) {
+		Message<?> message = MessageBuilder.withPayload(text.getBytes(StandardCharsets.UTF_8)).build();
+		return getMessageConverter().fromMessage(message, dataType);
+	}
+
+	@Override
+	public String getFormat() {
+		String raw = """
+				Your response should be in JSON format.
+				The data structure for the JSON should match this Java class: %s
+				Do not include any explanations, only provide a RFC8259 compliant JSON response following this format without deviation.
+				 """;
+		return String.format(raw, dataType.getCanonicalName());
+	}
+
+}

spring-ai-openai/src/test/java/org/springframework/ai/openai/client/ClientIntegrationTests.java

@@ -1,9 +1,8 @@
 package org.springframework.ai.openai.client;
 
 import org.junit.jupiter.api.Test;
-import org.springframework.ai.client.AiClient;
 import org.springframework.ai.client.Generation;
-import org.springframework.ai.parser.OutputParser;
+import org.springframework.ai.parser.JsonOutputParser;
 import org.springframework.ai.parser.ListOutputParser;
 import org.springframework.ai.prompt.Prompt;
 import org.springframework.ai.prompt.PromptTemplate;
@@ -17,6 +16,8 @@ import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.core.io.Resource;
 
+import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -85,4 +86,25 @@ class ClientIntegrationTests {
 
 	}
 
+	@Test
+	void jsonOutputParser() {
+		JsonOutputParser outputParser = new JsonOutputParser(HashMap.class);
+
+		String format = outputParser.getFormat();
+		String template = """
+				Provide me a List of {subject}
+				{format}
+				""";
+		PromptTemplate promptTemplate = new PromptTemplate(template,
+				Map.of("subject", "an array of numbers from 1 to 9 under they key name 'numbers'", "format", format));
+		Prompt prompt = new Prompt(promptTemplate.createMessage());
+		Generation generation = openAiClient.generate(prompt).getGeneration();
+
+		Object result = outputParser.parse(generation.getText());
+		System.out.println(result);
+		assertThat(result).isNotNull();
+		assertThat(((Map) result).get("numbers")).isEqualTo(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9));
+
+	}
+
 }