Has generators set default template engine (#11245)

* Adds default template engine to generators

* Fixes sample batch generation

bin/configs/python-experimental.yaml

@@ -2,7 +2,6 @@ generatorName: python-experimental
 outputDir: samples/openapi3/client/petstore/python-experimental
 inputSpec: modules/openapi-generator/src/test/resources/3_0/python-experimental/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml
 templateDir: modules/openapi-generator/src/main/resources/python-experimental
-templatingEngineName: handlebars
 additionalProperties:
   packageName: petstore_api
   recursionLimit: "1234"

modules/openapi-generator-core/src/main/java/org/openapitools/codegen/config/WorkflowSettings.java

@@ -46,7 +46,7 @@ public class WorkflowSettings {
     public static final boolean DEFAULT_ENABLE_MINIMAL_UPDATE = false;
     public static final boolean DEFAULT_STRICT_SPEC_BEHAVIOR = true;
     public static final boolean DEFAULT_GENERATE_ALIAS_AS_MODEL = false;
-    public static final String DEFAULT_TEMPLATING_ENGINE_NAME = "mustache";
+    public static final String DEFAULT_TEMPLATING_ENGINE_NAME = null; // this is set by the generator
     public static final Map<String, String> DEFAULT_GLOBAL_PROPERTIES = Collections.unmodifiableMap(new HashMap<>());
 
     private String inputSpec;

modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConfig.java

@@ -304,4 +304,6 @@ public interface CodegenConfig {
     void setRemoveEnumValuePrefix(boolean removeEnumValuePrefix);
 
     Schema unaliasSchema(Schema schema, Map<String, String> usedImportMappings);
+
+    public String defaultTemplatingEngine();
 }

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -7356,4 +7356,9 @@ public class DefaultCodegen implements CodegenConfig {
         }
         return xOf;
     }
+
+    @Override
+    public String defaultTemplatingEngine() {
+        return "mustache";
+    }
 }

modules/openapi-generator/src/main/java/org/openapitools/codegen/config/CodegenConfigurator.java

@@ -91,11 +91,18 @@ public class CodegenConfigurator {
             WorkflowSettings workflowSettings = settings.getWorkflowSettings();
             List<TemplateDefinition> userDefinedTemplateSettings = settings.getFiles();
 
+            CodegenConfig config = CodegenConfigLoader.forName(generatorSettings.getGeneratorName());
+            String templatingEngineName = workflowSettings.getTemplatingEngineName();
+            if (isEmpty(templatingEngineName)) {
+                // if templatingEngineName is empty check the config for a default
+                templatingEngineName = config.defaultTemplatingEngine();
+            }
+
             // We copy "cached" properties into configurator so it is appropriately configured with all settings in external files.
             // FIXME: target is to eventually move away from CodegenConfigurator properties except gen/workflow settings.
             configurator.generatorName = generatorSettings.getGeneratorName();
             configurator.inputSpec = workflowSettings.getInputSpec();
-            configurator.templatingEngineName = workflowSettings.getTemplatingEngineName();
+            configurator.templatingEngineName = templatingEngineName;
             if (workflowSettings.getGlobalProperties() != null) {
                 configurator.globalProperties.putAll(workflowSettings.getGlobalProperties());
             }
@@ -482,15 +489,17 @@ public class CodegenConfigurator {
         Validate.notEmpty(generatorName, "generator name must be specified");
         Validate.notEmpty(inputSpec, "input spec must be specified");
 
+        GeneratorSettings generatorSettings = generatorSettingsBuilder.build();
+        CodegenConfig config = CodegenConfigLoader.forName(generatorSettings.getGeneratorName());
         if (isEmpty(templatingEngineName)) {
-            // Built-in templates are mustache, but allow users to use a simplified handlebars engine for their custom templates.
+            // if templatingEngineName is empty check the config for a default
-            workflowSettingsBuilder.withTemplatingEngineName("mustache");
+            String defaultTemplatingEngine = config.defaultTemplatingEngine();
+            workflowSettingsBuilder.withTemplatingEngineName(defaultTemplatingEngine);
         } else {
             workflowSettingsBuilder.withTemplatingEngineName(templatingEngineName);
         }
 
         // at this point, all "additionalProperties" are set, and are now immutable per GeneratorSettings instance.
-        GeneratorSettings generatorSettings = generatorSettingsBuilder.build();
         WorkflowSettings workflowSettings = workflowSettingsBuilder.build();
 
         if (workflowSettings.isVerbose()) {

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PythonExperimentalClientCodegen.java

@@ -2075,4 +2075,9 @@ public class PythonExperimentalClientCodegen extends AbstractPythonCodegen {
         }
         return co;
     }
+
+    @Override
+    public String defaultTemplatingEngine() {
+        return "handlebars";
+    }
 }