jooby-apt: generate constructors from source controllers

- support default constructor with injected fields
- ref #3469

Author: jknack

modules/jooby-apt/src/main/java/io/jooby/internal/apt/MvcRouter.java

@@ -14,6 +14,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.*;
 import java.util.function.BiConsumer;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -181,7 +182,6 @@ private StringBuilder trimr(StringBuilder buffer) {
   }
 
   private StringBuilder constructors(String generatedName, boolean kt) {
-    var injectAnnotations = Set.of("javax.inject.Inject", "jakarta.inject.Inject");
     var constructors =
         getTargetType().getEnclosedElements().stream()
             .filter(
@@ -193,17 +193,15 @@ private StringBuilder constructors(String generatedName, boolean kt) {
     var targetType = getTargetType().getSimpleName();
     var buffer = new StringBuilder();
     buffer.append(System.lineSeparator());
+    // Inject could be at constructor or field level.
     var injectConstructor =
-        constructors.stream()
-            .filter(
-                it ->
-                    injectAnnotations.stream()
-                        .anyMatch(annotation -> findAnnotationByName(it, annotation) != null))
-            .findFirst()
-            .orElse(null);
+        constructors.stream().filter(hasInjectAnnotation()).findFirst().orElse(null);
+    var inject =
+        injectConstructor != null
+            || getTargetType().getEnclosedElements().stream().anyMatch(hasInjectAnnotation());
     final var defaultConstructor =
         constructors.stream().filter(it -> it.getParameters().isEmpty()).findFirst().orElse(null);
-    if (injectConstructor != null) {
+    if (inject) {
       constructor(
           generatedName,
           kt,
@@ -259,7 +257,7 @@ private StringBuilder constructors(String generatedName, boolean kt) {
       }
     }
 
-    if (injectConstructor != null) {
+    if (inject) {
       if (kt) {
         constructor(
             generatedName,
@@ -299,6 +297,13 @@ private StringBuilder constructors(String generatedName, boolean kt) {
     return trimr(buffer).append(System.lineSeparator());
   }
 
+  private static Predicate<Element> hasInjectAnnotation() {
+    var injectAnnotations = Set.of("javax.inject.Inject", "jakarta.inject.Inject");
+    return it ->
+        injectAnnotations.stream()
+            .anyMatch(annotation -> findAnnotationByName(it, annotation) != null);
+  }
+
   private void constructor(
       String generatedName,
       boolean kt,

modules/jooby-apt/src/test/java/tests/i3469/C3469FieldInject.java

@@ -0,0 +1,19 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package tests.i3469;
+
+import io.jooby.annotation.GET;
+import jakarta.inject.Inject;
+
+public class C3469FieldInject {
+
+  @Inject private Foo3469 foo;
+
+  @GET("/3469")
+  public String method() {
+    return foo.foo();
+  }
+}

modules/jooby-apt/src/test/java/tests/i3469/Issue3469.java

@@ -31,4 +31,13 @@ public void shouldGenerateConstructors() throws Exception {
               assertFalse(source.toString().contains("public C3469_()"));
             });
   }
+
+  @Test
+  public void shouldGenerateFieldInjectWithDefaultConstructor() throws Exception {
+    new ProcessorRunner(new C3469FieldInject())
+        .withSource(
+            source -> {
+              assertTrue(source.toString().contains("this(C3469FieldInject.class);"));
+            });
+  }
 }

tests/src/test/java/io/jooby/i2457/ControllersAppV12457.java

@@ -10,6 +10,6 @@
 public class ControllersAppV12457 extends Jooby {
 
   public ControllersAppV12457() {
-    mvc(ControllerV12457.class);
+    mvc(new ControllerV12457_());
   }
 }

tests/src/test/java/io/jooby/i2457/ControllersAppV22457.java

@@ -10,6 +10,6 @@
 public class ControllersAppV22457 extends Jooby {
 
   public ControllersAppV22457() {
-    mvc(ControllerV22457.class);
+    mvc(new ControllerV22457_());
   }
 }