Add toString to Message classes, and allow Resource to be used in PromptTemplate

spring-ai-core/src/main/java/org/springframework/ai/prompt/Prompt.java

@@ -16,12 +16,12 @@
 
 package org.springframework.ai.prompt;
 
+import org.springframework.ai.prompt.messages.Message;
+import org.springframework.ai.prompt.messages.UserMessage;
+
 import java.util.Collections;
 import java.util.List;
 
-import org.springframework.ai.prompt.messages.UserMessage;
-import org.springframework.ai.prompt.messages.Message;
-
 public class Prompt {
 
 	private List<Message> messages;
@@ -50,4 +50,9 @@ public class Prompt {
 		return this.messages;
 	}
 
+	@Override
+	public String toString() {
+		return "Prompt{" + "messages=" + messages + '}';
+	}
+
 }

spring-ai-core/src/main/java/org/springframework/ai/prompt/PromptTemplate.java

@@ -20,9 +20,14 @@ import org.antlr.runtime.Token;
 import org.antlr.runtime.TokenStream;
 import org.springframework.ai.prompt.messages.Message;
 import org.springframework.ai.prompt.messages.UserMessage;
+import org.springframework.core.io.Resource;
+import org.springframework.util.StreamUtils;
 import org.stringtemplate.v4.ST;
 import org.stringtemplate.v4.compiler.STLexer;
 
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.Charset;
 import java.util.*;
 import java.util.Map.Entry;
 import java.util.stream.Collectors;
@@ -40,6 +45,21 @@ public class PromptTemplate implements PromptTemplateActions {
 
 	private OutputParser outputParser;
 
+	public PromptTemplate(Resource resource) {
+		try (InputStream inputStream = resource.getInputStream()) {
+			this.template = StreamUtils.copyToString(inputStream, Charset.defaultCharset());
+		}
+		catch (IOException ex) {
+			throw new RuntimeException("Failed to read resource", ex);
+		}
+		try {
+			this.st = new ST(this.template, '{', '}');
+		}
+		catch (Exception ex) {
+			throw new IllegalArgumentException("The template string is not valid.", ex);
+		}
+	}
+
 	public PromptTemplate(String template) {
 		this.template = template;
 		// If the template string is not valid, an exception will be thrown
@@ -95,12 +115,26 @@ public class PromptTemplate implements PromptTemplateActions {
 	@Override
 	public String render(Map<String, Object> model) {
 		validate(model);
-		for (Entry<String, Object> stringObjectEntry : model.entrySet()) {
-			if (st.getAttribute(stringObjectEntry.getKey()) == null) {
-				st.add(stringObjectEntry.getKey(), stringObjectEntry.getValue());
+		for (Entry<String, Object> entry : model.entrySet()) {
+			if (st.getAttribute(entry.getKey()) == null) {
+				if (entry.getValue() instanceof Resource) {
+					st.add(entry.getKey(), renderResource((Resource) entry.getValue()));
+				}
+				else {
+					st.add(entry.getKey(), entry.getValue());
+				}
 			}
 		}
-		return st.render().trim();
+		return st.render();
+	}
+
+	private String renderResource(Resource resource) {
+		try (InputStream inputStream = resource.getInputStream()) {
+			return StreamUtils.copyToString(inputStream, Charset.defaultCharset());
+		}
+		catch (IOException ex) {
+			throw new RuntimeException(ex);
+		}
 	}
 
 	@Override

spring-ai-core/src/main/java/org/springframework/ai/prompt/messages/AssistantMessage.java

@@ -34,4 +34,10 @@ public class AssistantMessage extends AbstractMessage {
 		super(MessageType.ASSISTANT, content, properties);
 	}
 
+	@Override
+	public String toString() {
+		return "AssistantMessage{" + "content='" + content + '\'' + ", properties=" + properties + ", messageType="
+				+ messageType + '}';
+	}
+
 }

spring-ai-core/src/main/java/org/springframework/ai/prompt/messages/FunctionMessage.java

@@ -28,4 +28,10 @@ public class FunctionMessage extends AbstractMessage {
 		super(MessageType.SYSTEM, content, properties);
 	}
 
+	@Override
+	public String toString() {
+		return "FunctionMessage{" + "content='" + content + '\'' + ", properties=" + properties + ", messageType="
+				+ messageType + '}';
+	}
+
 }

spring-ai-core/src/main/java/org/springframework/ai/prompt/messages/SystemMessage.java

@@ -34,4 +34,10 @@ public class SystemMessage extends AbstractMessage {
 		super(MessageType.SYSTEM, content, properties);
 	}
 
+	@Override
+	public String toString() {
+		return "SystemMessage{" + "content='" + content + '\'' + ", properties=" + properties + ", messageType="
+				+ messageType + '}';
+	}
+
 }

spring-ai-core/src/main/java/org/springframework/ai/prompt/messages/UserMessage.java

@@ -33,4 +33,10 @@ public class UserMessage extends AbstractMessage {
 		super(MessageType.USER, message, properties);
 	}
 
+	@Override
+	public String toString() {
+		return "UserMessage{" + "content='" + content + '\'' + ", properties=" + properties + ", messageType="
+				+ messageType + '}';
+	}
+
 }