Allow Handlebars templates to extract fields from Java beans

semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/KernelFunctionFromPrompt.java

@@ -20,6 +20,7 @@
 import com.microsoft.semantickernel.services.chatcompletion.ChatCompletionService;
 import com.microsoft.semantickernel.services.textcompletion.TextGenerationService;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -439,6 +440,7 @@ public KernelFunction<T> build() {
                 name,
                 template,
                 templateFormat,
+                Collections.emptySet(),
                 description,
                 inputVariables,
                 outputVariable,

semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/PromptTemplateConfig.java

@@ -11,9 +11,11 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Set;
 import javax.annotation.Nullable;
 
 /**
@@ -43,6 +45,7 @@ public class PromptTemplateConfig {
     @Nullable
     private final String template;
     private final String templateFormat;
+    private final Set<PromptTemplateOption> promptTemplateOptions;
     @Nullable
     private final String description;
     private final List<InputVariable> inputVariables;
@@ -61,6 +64,7 @@ protected PromptTemplateConfig(String template) {
             DEFAULT_CONFIG_NAME,
             template,
             SEMANTIC_KERNEL_TEMPLATE_FORMAT,
+            Collections.emptySet(),
             "",
             Collections.emptyList(),
             new OutputVariable(String.class.getName(), "out"),
@@ -70,21 +74,23 @@ protected PromptTemplateConfig(String template) {
     /**
      * Constructor for a prompt template config
      *
-     * @param schema            Schema version
-     * @param name              Name of the template
-     * @param template          Template string
-     * @param templateFormat    Template format
-     * @param description       Description of the template
-     * @param inputVariables    Input variables
-     * @param outputVariable    Output variable
-     * @param executionSettings Execution settings
+     * @param schema                Schema version
+     * @param name                  Name of the template
+     * @param template              Template string
+     * @param templateFormat        Template format
+     * @param promptTemplateOptions Prompt template options
+     * @param description           Description of the template
+     * @param inputVariables        Input variables
+     * @param outputVariable        Output variable
+     * @param executionSettings     Execution settings
      */
     @JsonCreator
     public PromptTemplateConfig(
         @JsonProperty("schema") int schema,
         @Nullable @JsonProperty("name") String name,
         @Nullable @JsonProperty("template") String template,
         @Nullable @JsonProperty(value = "template_format", defaultValue = SEMANTIC_KERNEL_TEMPLATE_FORMAT) String templateFormat,
+        @Nullable @JsonProperty(value = "prompt_template_options") Set<PromptTemplateOption> promptTemplateOptions,
         @Nullable @JsonProperty("description") String description,
         @Nullable @JsonProperty("input_variables") List<InputVariable> inputVariables,
         @Nullable @JsonProperty("output_variable") OutputVariable outputVariable,
@@ -96,6 +102,10 @@ public PromptTemplateConfig(
             templateFormat = SEMANTIC_KERNEL_TEMPLATE_FORMAT;
         }
         this.templateFormat = templateFormat;
+        if (promptTemplateOptions == null) {
+            promptTemplateOptions = new HashSet<>();
+        }
+        this.promptTemplateOptions = promptTemplateOptions;
         this.description = description;
         if (inputVariables == null) {
             this.inputVariables = new ArrayList<>();
@@ -127,6 +137,7 @@ protected PromptTemplateConfig(
         @Nullable String name,
         @Nullable String template,
         @Nullable String templateFormat,
+        @Nullable Set<PromptTemplateOption> promptTemplateOptions,
         @Nullable String description,
         @Nullable List<InputVariable> inputVariables,
         @Nullable OutputVariable outputVariable,
@@ -136,6 +147,7 @@ protected PromptTemplateConfig(
             name,
             template,
             templateFormat,
+            promptTemplateOptions,
             description,
             inputVariables,
             outputVariable,
@@ -152,6 +164,7 @@ public PromptTemplateConfig(PromptTemplateConfig promptTemplate) {
             promptTemplate.name,
             promptTemplate.template,
             promptTemplate.templateFormat,
+            promptTemplate.promptTemplateOptions,
             promptTemplate.description,
             promptTemplate.inputVariables,
             promptTemplate.outputVariable,
@@ -300,6 +313,15 @@ public int getSchema() {
         return schema;
     }
 
+    /**
+     * Get the prompt template options of the prompt template config.
+     *
+     * @return The prompt template options of the prompt template config.
+     */
+    public Set<PromptTemplateOption> getPromptTemplateOptions() {
+        return Collections.unmodifiableSet(promptTemplateOptions);
+    }
+
     /**
      * Create a builder for a prompt template config which is a clone of the current object.
      *
@@ -358,6 +380,7 @@ public static class Builder {
         @Nullable
         private String template;
         private String templateFormat = SEMANTIC_KERNEL_TEMPLATE_FORMAT;
+        private final Set<PromptTemplateOption> promptTemplateOptions = new HashSet<>();
         @Nullable
         private String description = null;
         private List<InputVariable> inputVariables = new ArrayList<>();
@@ -433,6 +456,11 @@ public Builder withTemplateFormat(String templateFormat) {
             return this;
         }
 
+        public Builder addPromptTemplateOption(PromptTemplateOption option) {
+            promptTemplateOptions.add(option);
+            return this;
+        }
+
         /**
          * Set the inputVariables of the prompt template config.
          *
@@ -477,6 +505,7 @@ public PromptTemplateConfig build() {
                 name,
                 template,
                 templateFormat,
+                promptTemplateOptions,
                 description,
                 inputVariables,
                 outputVariable,

semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/PromptTemplateOption.java

@@ -0,0 +1,16 @@
+// Copyright (c) Microsoft. All rights reserved.
+package com.microsoft.semantickernel.semanticfunctions;
+
+public enum PromptTemplateOption {
+    /**
+     * Allow methods on objects provided as arguments to an invocation, to be invoked when rendering
+     * a template and its return value used. Typically, this would be used to call a getter on an
+     * object i.e. {@code {{#each users}} {{userName}} {{/each}} } on a handlebars template will
+     * call the method {@code getUserName()} on each object in {@code users}.
+     * <p>
+     * WARNING: If this option is used, ensure that your template is trusted, and that objects added
+     * as arguments to an invocation, do not contain methods that are unsafe to be invoked when
+     * rendering a template.
+     */
+    ALLOW_CONTEXT_VARIABLE_METHOD_CALLS_UNSAFE
+}

semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/handlebars/HandlebarsPromptTemplate.java

@@ -9,6 +9,7 @@
 import com.github.jknack.handlebars.Helper;
 import com.github.jknack.handlebars.Options;
 import com.github.jknack.handlebars.ValueResolver;
+import com.github.jknack.handlebars.context.JavaBeanValueResolver;
 import com.microsoft.semantickernel.Kernel;
 import com.microsoft.semantickernel.contextvariables.ContextVariable;
 import com.microsoft.semantickernel.contextvariables.ContextVariableType;
@@ -21,6 +22,7 @@
 import com.microsoft.semantickernel.semanticfunctions.KernelFunctionArguments;
 import com.microsoft.semantickernel.semanticfunctions.PromptTemplate;
 import com.microsoft.semantickernel.semanticfunctions.PromptTemplateConfig;
+import com.microsoft.semantickernel.semanticfunctions.PromptTemplateOption;
 import com.microsoft.semantickernel.services.chatcompletion.ChatMessageContent;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
 import java.io.IOException;
@@ -35,7 +37,6 @@
 import java.util.stream.Collectors;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
-import org.apache.commons.text.StringEscapeUtils;
 import reactor.core.publisher.Mono;
 
 /**
@@ -168,7 +169,7 @@ public Set<Entry<String, Object>> propertySet(Object context) {
         }
     }
 
-    private static class HandleBarsPromptTemplateHandler {
+    private class HandleBarsPromptTemplateHandler {
 
         private final String template;
         private final Handlebars handlebars;
@@ -181,7 +182,7 @@ public HandleBarsPromptTemplateHandler(
             this.template = template;
             this.handlebars = new Handlebars();
             this.handlebars
-                .registerHelper("message", HandleBarsPromptTemplateHandler::handleMessage)
+                .registerHelper("message", this::handleMessage)
                 .registerHelper("each", handleEach(context))
                 .with(EscapingStrategy.XML);
 
@@ -190,7 +191,7 @@ public HandleBarsPromptTemplateHandler(
             // TODO: 1.0 Add more helpers
         }
 
-        private static Helper<Object> handleEach(InvocationContext invocationContext) {
+        private Helper<Object> handleEach(InvocationContext invocationContext) {
             return (context, options) -> {
                 if (context instanceof ContextVariable) {
                     return ((ContextVariable<?>) context)
@@ -227,7 +228,7 @@ private static Helper<Object> handleEach(InvocationContext invocationContext) {
         }
 
         @Nullable
-        private static CharSequence handleMessage(Object context, Options options)
+        private CharSequence handleMessage(Object context, Options options)
             throws IOException {
             String role = options.hash("role");
             String content = (String) options.fn(context);
@@ -258,7 +259,10 @@ public Mono<String> render(KernelFunctionArguments variables) {
                 resolvers.add(new MessageResolver());
                 resolvers.add(new ContextVariableResolver());
 
-                // resolvers.addAll(ValueResolver.defaultValueResolvers());
+                if (promptTemplate.getPromptTemplateOptions()
+                    .contains(PromptTemplateOption.ALLOW_CONTEXT_VARIABLE_METHOD_CALLS_UNSAFE)) {
+                    resolvers.add(JavaBeanValueResolver.INSTANCE);
+                }
 
                 Context context = Context
                     .newBuilder(variables)

semantickernel-api/src/test/java/com/microsoft/semantickernel/semanticfunctions/PromptTemplateConfigTest.java

@@ -5,6 +5,7 @@
 
 import com.microsoft.semantickernel.orchestration.PromptExecutionSettings;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import org.junit.jupiter.api.Test;
@@ -28,6 +29,7 @@ void testInstanceMadeWithBuilderEqualsInstanceMadeWithConstructor() {
             name,
             template,
             "semantic-kernel",
+            Collections.emptySet(),
             description,
             inputVariables,
             outputVariable,