improve: double brackets to handle non string values in object templates

Signed-off-by: Attila Mészáros <[email protected]>

README.md

@@ -67,8 +67,8 @@ spec:
   parent:
     apiVersion: glueoperator.sample/v1  # watches all the custom resource of type WebPage
     kind: WebPage
-    statusTemplate: | # update the status of the custom resource at the end of reconciliation
-      observedGeneration: {parent.metadata.generation}
+    status:  # update the status of the custom resource at the end of reconciliation
+      observedGeneration: "{{parent.metadata.generation}}" # since it's a non-string value needs double curly brackets 
   childResources:
     - name: htmlconfigmap
       resource:

docs/reference.md

@@ -8,8 +8,31 @@ Although it is limited only to Kubernetes resources it makes it very easy to use
 
 ## Generic Notes
 
-- All templates (both object and string based) uses [Qute templating engine](https://quarkus.io/guides/qute-reference). While objects allow only
-  placeholders, you can use the full power of qute in string templates.
+ - All templates (both object and string-based) uses [Qute templating engine](https://quarkus.io/guides/qute-reference). While objects allow only
+   placeholders, you can use the full power of qute in string templates.
+
+   ONLY for object-based templates (thus not string templates) the values can be set using the placeholder notation from Qute: 
+   ```yaml
+   value: "{string.value.reference}" 
+   ```
+   With this standard notation, the result value will be always encoded in double quotes:
+    ```yaml
+   value: "1" 
+   ```
+   Since there is no simple way to check if the referenced value is a string or other value
+   (boolean, numeric, etc) for non-string values, user should use double brackets:
+    ```yaml
+   value: "{{nonstring.value.reference}}" 
+   ```
+   what would result in a value without enclosed double quotes in the produced yaml:
+    ```yaml
+   value: 1 
+   ```
+   See sample [here](https://github.com/java-operator-sdk/kubernetes-glue-operator/blob/main/src/test/resources/sample/webpage/webpage.operator.yaml#L10).
+   Implementation wise, this is a preprocessor that strips the enclosed quotes and additional curly bracket
+   before it is passed to Qute.
+   In the future, we might remove such obligation by checking the type 
+   of the target value in the related schema.
 
 ## [Glue resource](https://github.com/java-operator-sdk/kubernetes-glue-operator/releases/latest/download/glues.glue-v1.yml)
 

src/main/java/io/javaoperatorsdk/operator/glue/templating/GenericTemplateHandler.java

@@ -34,7 +34,7 @@ public String processTemplate(Map<String, Map<?, ?>> data, String template,
 
   private String handleDoubleCurlyBrackets(String template) {
     template = template.replace("\"{{", "{");
-    return template.replace("}}\n", "}");
+    return template.replace("}}\"", "}");
   }
 
   public String processInputAndTemplate(Map<String, GenericKubernetesResource> data,

src/test/java/io/javaoperatorsdk/operator/glue/templating/GenericTemplateHandlerTest.java

@@ -1,14 +1,38 @@
 package io.javaoperatorsdk.operator.glue.templating;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import org.junit.jupiter.api.Test;
 
+import io.fabric8.kubernetes.client.utils.Serialization;
+
 import static org.junit.jupiter.api.Assertions.*;
 
 class GenericTemplateHandlerTest {
 
+  GenericTemplateHandler templateHandler = new GenericTemplateHandler();
+
   @Test
   void testDoubleCurlyBrackets() {
-    fail();
+    var template = """
+          intValue: "{{spec.intvalue}}"
+          stringValue: "{spec.stringvalue}"
+        """;
+
+    Map<String, Map<?, ?>> data = new HashMap<>();
+
+    Map values = new HashMap();
+    values.put("intvalue", 1);
+    values.put("stringvalue", "value1");
+    data.put("spec", values);
+
+    var result = templateHandler.processTemplate(data, template, true);
+
+    Map mapResult = Serialization.unmarshal(result, Map.class);
+
+    assertEquals(1, mapResult.get("intValue"));
+    assertEquals("value1", mapResult.get("stringValue"));
   }
 
 }

src/test/resources/sample/webpage/webpage.operator.yaml

@@ -6,8 +6,8 @@ spec:
   parent:
     apiVersion: glueoperator.sample/v1
     kind: WebPage
-    statusTemplate: |
-      observedGeneration: {parent.metadata.generation}
+    status:
+      observedGeneration: "{{parent.metadata.generation}}"
   childResources:
     - name: htmlconfigmap
       resource: