Crud Controller

ControllerAgent.java

package controllers;

import models.Model;
import models.User;
import play.api.templates.Html;
import play.data.Form;
import play.mvc.Controller;
import play.mvc.Result;

public abstract class ControllerAgent<T extends Model, F1, F2> {
    
    protected Form<F1> composeForm;
    protected Form<F2> editForm;
    
    public ControllerAgent(Class<F1> clazzComposeForm, Class<F2> clazzEditForm) {
        this.composeForm = Controller.form(clazzComposeForm);
        this.editForm = Controller.form(clazzEditForm);
    }
    
    protected abstract Html displayCompose(Form<F1> composeForm, Long... preIds);
    protected abstract Html displayItem(T element, Long... preIds);
    protected abstract Html displayEditForm(Form<F2> editForm, T element, Long... preIds);
    
    protected abstract T createFromForm(Form<F1> composeForm, Long... preIds);
    protected abstract T editFromForm(T element, Form<F2> editForm);
    protected abstract F2 translateItemToEditFormInstance(T element);
    
    public Result compose(Long... preIds) {
        return Controller.ok(displayCompose(composeForm, preIds));
    }
    
    public Result create(Long... preIds) {
        Form<F1> filledForm = composeForm.bindFromRequest();
        if (filledForm.hasErrors()) return Controller.status(409,displayCompose(filledForm, preIds));
        T element = createFromForm(filledForm, preIds);
        return Controller.ok(displayItem(element, preIds));
    }
    
    public Result edit(T element, Long... preIds) {
        if (element==null) return Controller.notFound();
        return Controller.ok(displayEditForm(editForm.fill(translateItemToEditFormInstance(element)), element, preIds));
    }
    
    public Result update(T element, Long... preIds) {
        if (element==null) return Controller.notFound();
        Form<F2> filledForm = editForm.bindFromRequest();
        if (filledForm.hasErrors()) return Controller.status(409,displayEditForm(filledForm, element, preIds));
        T editItem = editFromForm(element, filledForm);
        return Controller.ok(displayItem(editItem, preIds));
    }
    
    public Result delete(T element, User user) {
        if (element==null) return Controller.notFound();
        if (element.deleteBy(user)) return Controller.noContent();
        else return Controller.unauthorized();
    }
    
    public abstract static class DefaultControllerAgent<T extends Model> extends ControllerAgent<T, T, T> {

        
        public DefaultControllerAgent(Class<T> clazz) {
            super(clazz,clazz);
        }
        
        protected abstract T createItemFromForm(T element, Long... preIds);

        @Override
        protected T createFromForm(Form<T> composeForm, Long... preIds) {
            return createItemFromForm(composeForm.get(), preIds);
        }

        @Override
        protected T editFromForm(T element, Form<T> editForm) {
            T editItem = editForm.get();
            editItem.update(element.id);
            return editItem;
        }

        @Override
        protected T translateItemToEditFormInstance(T element) {
            return element;
        }
        
        public Result delete(T element) {
            return delete(element, Auth.getUser());
        }
        
    }
    
}

VideoNote.java

package controllers;

import models.Video;
import models.VideoNote;
import play.api.templates.Html;
import play.data.Form;
import play.mvc.Result;
import play.mvc.Controller;
import views.html.video_notes.compose;
import views.html.video_notes.item;
import controllers.ControllerAgent.DefaultControllerAgent;

public class VideoNotes extends Controller {

    private static DefaultControllerAgent<VideoNote> agent = 
            new DefaultControllerAgent<VideoNote>(VideoNote.class) {

                @Override
                protected Html displayCompose(Form<VideoNote> composeForm, Long... preIds) {
                    return compose.render(Video.find.ref(preIds[0]),composeForm);
                }

                @Override
                protected Html displayItem(VideoNote element, Long... preIds) {
                    return item.render(element);
                }

                @Override
                protected VideoNote createItemFromForm(VideoNote element, Long... preIds) {
                    return VideoNote.createFromForm(element, Auth.getUser(), Video.find.ref(preIds[0]));
                }

                @Override
                protected Html displayEditForm(Form<VideoNote> editForm, VideoNote element, Long... preIds) {
                    throw new NoSuchMethodError("no edit for VideoNote yet");
                }};
    
    public static Result compose(Long videoId) {
        return agent.compose(videoId);
    }
    
    public static Result create(Long videoId) {
        return agent.create(videoId);
    }
    
    public static Result delete(Long videoId, Long id) {
        return agent.delete(VideoNote.find.byId(id));
    }
    
}