getting null value from @Requestbody-CodePudding

I am in the process of adding a DTO layer to a restful api. Before, the program used entity (Recipe and Ingredient) directly and now I added a new DTO layer in between (RecipeDTO IngredientDTO). However, the moment I made the change I started getting Null values from @RequestBody. Each recipe contains a list of Ingredients and it is the list of ingredients that are returning null values, the recipe by itself is returning fine.

The controller looks like this

package com.example.recipes.controller;
import com.example.recipes.DTO.RecipeDTO;
import com.example.recipes.Service.RecipeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
/*...*/
    @PostMapping(path = "/post")
    public void postRecipes(@RequestBody RecipeDTO recipeDTO){
        recipeService.postRecipes(recipeDTO);
    }
/*...*/

Recipe Entity

package com.example.recipes.Entity;
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;
import java.time.LocalDateTime;
import java.util.List;

@Data
@Entity
@Table(name = "recipe", schema = "public")
@AllArgsConstructor
@NoArgsConstructor
public class Recipe {
    @Id
    @GeneratedValue(
            strategy = GenerationType.IDENTITY
    )
    @Column(name = "id", updatable = false, nullable = false)
    private long id;
    @Column(name = "name")
    private String name;
    @Column(name = "instructions")
    private String instructions;
    @OneToMany(mappedBy = "recipe")
    private List<Ingredient> ingredients;
    @JsonProperty("date_added")
    private String dateAdded = String.valueOf(LocalDateTime.now());
    @JsonProperty("last_edited")
    private String lastEdited = String.valueOf(LocalDateTime.now());
}

RecipeDTO

package com.example.recipes.DTO;
import lombok.*;

import javax.persistence.OneToMany;
import java.time.LocalDateTime;
import java.util.List;

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
@ToString
public class RecipeDTO {
    private long id;
    private String name;
    private String instructions;
    private List<IngredientDTO> ingredientsDTO;
    private String dateAdded = String.valueOf(LocalDateTime.now());
    private String lastEdited = String.valueOf(LocalDateTime.now());

    public RecipeDTO(long id, String name, String instructions, String dateAdded, String lastEdited) {
        this.id = id;
        this.name = name;
        this.instructions = instructions;
        this.dateAdded = dateAdded;
        this.lastEdited = lastEdited;
    }
}

Ingredient Entity

package com.example.recipes.Entity;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import javax.persistence.*;
@Data
@Entity
@Table(name = "Ingredient")
@NoArgsConstructor
public class Ingredient {
    @Id
    @GeneratedValue(
            strategy = GenerationType.IDENTITY
    )
    @JsonProperty("ingredient_id")
    private long ingredient_ID;
    @JsonProperty("ingredient_name")
    private String ingredientName;
    @Column(name = "amount")
    private int amount;
    @Column(name = "unit")
    private String unit;
    @ManyToOne
    @JoinColumn(name = "recipe_id")
    @ToString.Exclude
    @JsonIgnore
    private Recipe recipe;
}

IngredientDTO

package com.example.recipes.DTO;
import lombok.*;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class IngredientDTO {
    private long ingredientID;
    private String ingredientName;
    private int amount;
    private String unit;
}

the json i sent

{
    "name":"unique2",
    "ingredients":[
        {
            "ingredient_name":"Atlantic",
            "amount":13, 
            "unit":"ton"
        },
        {
            "ingredient_name":"Pacific",
            "amount":15, 
            "unit":"boatload"
        },
        {
            "ingredient_name":"Indian",
            "amount":38, 
            "unit":"trucload"
        }
    ],
    "instructions":"easy on the salt"
}

and the @requestbody the ingredientsDTO is null

this is recipe: RecipeDTO(id=0, name=unique2, instructions=easy on the salt, ingredientsDTO=null, dateAdded=2022-08-08T15:04:10.678748100, lastEdited=2022-08-08T15:04:10.678748100)

Edit: I have just tried copying the code from the entity classes and pasting them in the DTO classes and it still returning null...

package com.example.recipes.DTO;
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;
import java.time.LocalDateTime;
import java.util.List;

@Data
@Entity
@Table(name = "recipe", schema = "public")
@AllArgsConstructor
@NoArgsConstructor
public class RecipeDTO {
    @Id
    @GeneratedValue(
            strategy = GenerationType.IDENTITY
    )
    @Column(name = "id", updatable = false, nullable = false)
    private long id;
    @Column(name = "name")
    private String name;
    @Column(name = "instructions")
    private String instructions;
    @OneToMany(mappedBy = "recipeDTO")
    private List<IngredientDTO> ingredientDTOs;
    @JsonProperty("date_added")
    private String dateAdded = String.valueOf(LocalDateTime.now());
    @JsonProperty("last_edited")
    private String lastEdited = String.valueOf(LocalDateTime.now());

    public RecipeDTO(long id, String name, String instructions, String dateAdded, String lastEdited) {
        this.id = id;
        this.name = name;
        this.instructions = instructions;
        this.dateAdded = dateAdded;
        this.lastEdited = lastEdited;
    }
}

package com.example.recipes.DTO;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import javax.persistence.*;
@Data
@Entity
@Table(name = "Ingredient")
@NoArgsConstructor
public class IngredientDTO {
    @Id
    @GeneratedValue(
            strategy = GenerationType.IDENTITY
    )
    @JsonProperty("ingredient_id")
    private long ingredientID;
    @JsonProperty("ingredient_name")
    private String ingredientName;
    @Column(name = "amount")
    private int amount;
    @Column(name = "unit")
    private String unit;
    @ManyToOne
    @JoinColumn(name = "recipe_id")
    @ToString.Exclude
    @JsonIgnore
    private RecipeDTO recipeDTO;

    public IngredientDTO(long ingredientID, String ingredientName, int amount, String unit) {
        this.ingredientID = ingredientID;
        this.ingredientName = ingredientName;
        this.amount = amount;
        this.unit = unit;
    }
}

@RequestBody

this is recipe: RecipeDTO(id=0, name=unique2, instructions=easy on the salt, ingredientDTOs=null, dateAdded=2022-08-08T15:24:19.325806500, lastEdited=2022-08-08T15:24:19.325806500)
these are the ingredients: null
this is ingredientDTO: null
this is ingredientDTO: null

Edit2: I tried posting only the ingredientDTO and the @RequestBody was able to pick it up just fine

//this is fine
    public void testRecipePost(@RequestBody IngredientDTO ingredientDTO) {
        System.out.println("ingredientDTO: "   ingredientDTO);
    }

CodePudding user response：

You can replace

@OneToMany(mappedBy = "recipeDTO")
private List<IngredientDTO> ingredientDTOs;

@OneToMany(mappedBy = "recipeDTO")
private List<IngredientDTO> ingredients;

Or adding

@JsonProperty("ingredients")

Example:

@JsonProperty("ingredients")
@OneToMany(mappedBy = "recipeDTO")
private List<IngredientDTO> ingredientDTOs;

The reason for null is because Jackson doesn't know how to deserialise your fields properly with different names.

CodePudding user response：

In the json, the name is ingredients but, in the DTO, it is ingredientsDTO. Those 2 need to match.

CodePudding user response：

You request

{
    "name":"unique2",
    "ingredients":[...]

here the name of array you are passing in Json is different in the entity you are using.

Your DTO

 @OneToMany(mappedBy = "recipeDTO")
    private List<IngredientDTO> ingredientDTOs;

The name of fields in JSON request and Entity must match.

Change the name of field private List<IngredientDTO> ingredientDTOs; to ingredients.