fix: Throw NonTransientAiException on syntax errors in prompt templates

IAE/ISE are too generic, it's hard to use libraries that throw them.

Using NonTransientAiException clearly marks the exception as coming
from Spring AI, plus will integrate nicely with code that already
avoids re-sending requests when faced with this exception.

Signed-off-by: Piotr Kubowicz <[email protected]>

Author: pkubowicz

spring-ai-template-st/pom.xml

@@ -48,6 +48,12 @@
             <version>${project.parent.version}</version>
         </dependency>
 
+        <dependency>
+            <groupId>org.springframework.ai</groupId>
+            <artifactId>spring-ai-retry</artifactId>
+            <version>${project.parent.version}</version>
+        </dependency>
+
         <dependency>
             <groupId>org.antlr</groupId>
             <artifactId>ST4</artifactId>
@@ -74,4 +80,4 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
-</project>
+</project>

spring-ai-template-st/src/main/java/org/springframework/ai/template/st/StTemplateRenderer.java

@@ -24,6 +24,7 @@
 import org.antlr.runtime.TokenStream;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.ai.retry.NonTransientAiException;
 import org.stringtemplate.v4.ST;
 import org.stringtemplate.v4.compiler.Compiler;
 import org.stringtemplate.v4.compiler.STLexer;
@@ -115,7 +116,7 @@ private ST createST(String template) {
 			return new ST(template, this.startDelimiterToken, this.endDelimiterToken);
 		}
 		catch (Exception ex) {
-			throw new IllegalArgumentException("The template string is not valid.", ex);
+			throw new NonTransientAiException("The template string is not valid.", ex);
 		}
 	}
 
@@ -137,7 +138,7 @@ private Set<String> validate(ST st, Map<String, Object> templateVariables) {
 				logger.warn(VALIDATION_MESSAGE.formatted(missingVariables));
 			}
 			else if (this.validationMode == ValidationMode.THROW) {
-				throw new IllegalStateException(VALIDATION_MESSAGE.formatted(missingVariables));
+				throw new NonTransientAiException(VALIDATION_MESSAGE.formatted(missingVariables));
 			}
 		}
 		return missingVariables;

spring-ai-template-st/src/test/java/org/springframework/ai/template/st/StTemplateRendererTests.java

@@ -21,6 +21,7 @@
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.ai.retry.NonTransientAiException;
 import org.springframework.ai.template.ValidationMode;
 import org.springframework.test.util.ReflectionTestUtils;
 
@@ -107,7 +108,7 @@ void shouldThrowExceptionForInvalidTemplateSyntax() {
 		Map<String, Object> variables = new HashMap<>();
 		variables.put("name", "Spring AI");
 
-		assertThatThrownBy(() -> renderer.apply("Hello {name!", variables)).isInstanceOf(IllegalArgumentException.class)
+		assertThatThrownBy(() -> renderer.apply("Hello {name!", variables)).isInstanceOf(NonTransientAiException.class)
 			.hasMessageContaining("The template string is not valid.");
 	}
 
@@ -118,7 +119,7 @@ void shouldThrowExceptionForMissingVariablesInThrowMode() {
 		variables.put("greeting", "Hello");
 
 		assertThatThrownBy(() -> renderer.apply("{greeting} {name}!", variables))
-			.isInstanceOf(IllegalStateException.class)
+			.isInstanceOf(NonTransientAiException.class)
 			.hasMessageContaining(
 					"Not all variables were replaced in the template. Missing variable names are: [name]");
 	}