#22 - ENH: Support Kotlin non-nullable properties and constructor params

Author: rbygrave

src/main/java/io/dinject/javalin/generator/ElementReader.java

@@ -32,6 +32,9 @@ public class ElementReader {
   private boolean impliedParamType;
   private String paramDefault;
 
+  private boolean notNullKotlin;
+  private boolean notNullJavax;
+
   ElementReader(Element element, ProcessingContext ctx, ParamType defaultType, boolean formMarker) {
     this(element, typeDef(element.asType()), ctx, defaultType, formMarker);
   }
@@ -51,6 +54,10 @@ public class ElementReader {
   }
 
   private void readAnnotations(Element element, ParamType defaultType) {
+
+    notNullKotlin = (element.getAnnotation(org.jetbrains.annotations.NotNull.class) != null);
+    notNullJavax = (element.getAnnotation(javax.validation.constraints.NotNull.class) != null);
+
     Default defaultVal = element.getAnnotation(Default.class);
     if (defaultVal != null) {
       this.paramDefault = defaultVal.value();
@@ -234,7 +241,14 @@ private boolean setValue(Append writer, PathSegments segments, String shortType)
       if (hasParamDefault()) {
         writer.append("ctx.%s(\"%s\",\"%s\")", paramType, paramName, paramDefault);
       } else {
+        boolean checkNull = notNullKotlin || (paramType == ParamType.FORMPARAM && typeHandler.isPrimitive());
+        if (checkNull) {
+          writer.append("checkNull(");
+        }
         writer.append("ctx.%s(\"%s\")", paramType, paramName);
+        if (checkNull) {
+          writer.append(", \"%s\")", paramName);
+        }
       }
     }
 

src/main/java/io/dinject/javalin/generator/TypeHandler.java

@@ -24,4 +24,9 @@ interface TypeHandler {
    * The short name.
    */
   String shortName();
+
+  /**
+   * Return true if this is a primitive type.
+   */
+  boolean isPrimitive();
 }

src/main/java/io/dinject/javalin/generator/TypeMap.java

@@ -129,6 +129,11 @@ static abstract class JavaLangType implements TypeHandler {
       this.shortName = shortName;
     }
 
+    @Override
+    public boolean isPrimitive() {
+      return false;
+    }
+
     @Override
     public String shortName() {
       return shortName;
@@ -156,6 +161,11 @@ static abstract class Primitive implements TypeHandler {
       this.type = type;
     }
 
+    @Override
+    public boolean isPrimitive() {
+      return true;
+    }
+
     @Override
     public String shortName() {
       return type;
@@ -234,6 +244,11 @@ static abstract class ObjectHandler implements TypeHandler {
       this.toMethod = "to" + shortName + "(";
     }
 
+    @Override
+    public boolean isPrimitive() {
+      return false;
+    }
+
     @Override
     public String getImportType() {
       return importType;

src/main/java/org/jetbrains/annotations/NotNull.java

@@ -0,0 +1,14 @@
+package org.jetbrains.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Retention(RetentionPolicy.CLASS)
+@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.LOCAL_VARIABLE})
+public @interface NotNull {
+  String value() default "";
+}