Spring mongo 数据存储库 findAll() 返回空？

Question

I'm a newbie in Spring Framework. I'm trying to create a small REST API by using Spring Rest with MongoDB. And when I create the repository to get data from MongoDb, the findAll() function always return an empty list. Here is my repository:

   @RepositoryRestResource(collectionResourceRel = "meal", path = "meal")
   public interface MealRepository extends MongoRepository<Meal, Integer> {

       @Override
       public List<Meal> findAll();

       @Override
       public Meal findOne(Integer id);
   }

And Controller:

@RestController
public class MealApiController {

    @Autowired
    MealRepository mMealRepository;

    @RequestMapping(value = "/meal/detail", method = RequestMethod.GET)
    public @ResponseBody Meal mealDetailGet(@RequestParam(value = "id", required = true) Integer id) {
        Meal meal = mMealRepository.findOne(id);
        return meal;
    }

    @RequestMapping(value = "/meal/all", method = RequestMethod.GET)
    public @ResponseBody List<Meal> getAllMeal() {
        return mMealRepository.findAll();
    }

    @RequestMapping(value = "/meal/list", method = RequestMethod.GET)
    public @ResponseBody List<Meal> mealListGet(@RequestParam(value = "menu_id", required = true) Integer menuId) {
        List<Meal> response = mMealRepository.findByMenuId(menuId);
        return response;
    }

}

Meal model:

@Document(collection = "meal_items")
public class Meal {

    @Id
    @JsonProperty("_id")
    private int id;

    @JsonProperty("menu_id")
    private int menuId;

    @JsonProperty("name")
    private String name = null;

    @JsonProperty("image")
    private List<String> image = new ArrayList<String>();

    @JsonProperty("material")
    private List<String> material = new ArrayList<String>();

    @JsonProperty("guide")
    private List<String> guide = new ArrayList<String>();

    public Meal id(int id) {
        this.id = id;
        return this;
    }

    /**
     * Unique identifier representing a specific Meal.
     * 
     * @return id
     **/
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Meal menuId(int menuId) {
        this.menuId = menuId;
        return this;
    }

    /**
     * Unique identifier representing a specific Menu containing the meal.
     * 
     * @return menuId
     **/
    public int getMenuId() {
        return menuId;
    }

    public void setMenuId(int menuId) {
        this.menuId = menuId;
    }

    public Meal name(String name) {
        this.name = name;
        return this;
    }

    /**
     * Display name of meal.
     * 
     * @return name
     **/
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Meal image(List<String> image) {
        this.image = image;
        return this;
    }

    public Meal addImageItem(String imageItem) {
        this.image.add(imageItem);
        return this;
    }

    /**
     * Image URL representing the meal.
     * 
     * @return image
     **/
    public List<String> getImage() {
        return image;
    }

    public void setImage(List<String> image) {
        this.image = image;
    }

    public Meal material(List<String> material) {
        this.material = material;
        return this;
    }

    public Meal addMaterialItem(String materialItem) {
        this.material.add(materialItem);
        return this;
    }

    /**
     * List material used to cook the meal.
     * 
     * @return material
     **/
    public List<String> getMaterial() {
        return material;
    }

    public void setMaterial(List<String> material) {
        this.material = material;
    }

    public Meal guide(List<String> guide) {
        this.guide = guide;
        return this;
    }

    public Meal addGuideItem(String guideItem) {
        this.guide.add(guideItem);
        return this;
    }

    /**
     * Steps cooking the meal.
     * 
     * @return guide
     **/
    public List<String> getGuide() {
        return guide;
    }

    public void setGuide(List<String> guide) {
        this.guide = guide;
    }

    @Override
    public boolean equals(java.lang.Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        Meal meal = (Meal) o;
        return Objects.equals(this.id, meal.id) && Objects.equals(this.menuId, meal.menuId)
                && Objects.equals(this.name, meal.name) && Objects.equals(this.image, meal.image)
                && Objects.equals(this.material, meal.material) && Objects.equals(this.guide, meal.guide);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, menuId, name, image, material, guide);
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("class Meal {\n");

        sb.append("    id: ").append(toIndentedString(id)).append("\n");
        sb.append("    menuId: ").append(toIndentedString(menuId)).append("\n");
        sb.append("    name: ").append(toIndentedString(name)).append("\n");
        sb.append("    image: ").append(toIndentedString(image)).append("\n");
        sb.append("    material: ").append(toIndentedString(material)).append("\n");
        sb.append("    guide: ").append(toIndentedString(guide)).append("\n");
        sb.append("}");
        return sb.toString();
    }

    /**
     * Convert the given object to string with each line indented by 4 spaces
     * (except the first line).
     */
    private String toIndentedString(java.lang.Object o) {
        if (o == null) {
            return "null";
        }
        return o.toString().replace("\n", "\n    ");
    }
}

Answer 1

A couple of things.
Firstly, this behaviour is not reproducible. It works fine.

Secondly, you don't need a separate controller( @RestController ) class to expose your REST endpoints(unless needed for specific reasons). When you use spring-data-rest( @RepositoryRestResource ), spring exposes endpoints for you, including endpoints for custom querymethods like findByMenuId .
In your example, just delete the controller class and restart the application. And try to hit http://host:port/meal from the browser, it will display all the possible options as links, which is self-explanatory.