Spring数据Jpa中一对多映射的JSON结果出错

Question

所有者实体： PriceListItemTest.java

@JsonPropertyOrder({"pricingUOMCode","lineTypeCode","primaryPricingUOMFlag","priceListId","itemId","priceListItemId"})
@Entity
@Table(name = "QP_PRICE_LIST_ITEMS")
public class PriceListItemTest implements Serializable{

    @Column(name = "price_list_item_id")    
    private String priceListItemId;

    @Column(name = "pricing_uom_code")  
    private String pricingUOMCode; 

    @Column(name = "line_type_code")    
    private String lineTypeCode; 

    @Column(name = "primary_pricing_uom_flag")  
    private String primaryPricingUOMFlag;

    @Id
    @Column(name = "item_id")   
    private String itemId;

    @OneToMany(mappedBy = "priceListItemsTest", cascade = CascadeType.ALL)
    private List<ItemDetailTest> itemDetailsTest;

    // getters and setters
}

和实体2： ItemDetailTest.java

@JsonPropertyOrder({"itemNumber","inventoryItemId","organizationId"})
@Entity
@Table(name = "egp_system_items_b")
public class ItemDetailTest implements Serializable {

    @Id
    @Column(name = "inventory_item_id") 
    private String inventoryItemId; 

    @Column(name = "item_number")   
    private String itemNumber; 

    @Column(name = "organization_id")   
    private String organizationId;


//   To be used for bidirectional   
    @ManyToOne//(fetch = FetchType.LAZY)
    private PriceListItemTest priceListItemsTest;

    // getters and setters
}

RestController在检索JSON结果时返回错误。

{
    "timestamp": "2018-10-23T14:05:26.248+0000",
    "status": 500,
    "error": "Internal Server Error",
    "message": "Could not write JSON: could not extract ResultSet; nested exception is com.fasterxml.jackson.databind.JsonMappingException: could not extract ResultSet (through reference chain: java.util.ArrayList[0]->com.Pricing.Pricing_App.model.PriceListItemTest[\"itemDetailsTest\"])",
    "path": "/getByItemIdTest"
}

可能是地图错了
如果它有oneToone映射，但面临OneToMany的问题，则工作正常。有人能帮我解决这个错误吗？

编辑：控制器：

@RestController
public class PriceListItemControllerTest {

    @Autowired
    private PriceListItemRepositoryTest priceListItemRepositoryTest;

    @GetMapping(value="/getByItemIdTest")
    public List<PriceListItemTest> getByItemIdTest(@RequestParam("itemId") String itemId) {
        return priceListItemRepositoryTest.findByItemId(itemId);
    }

}

Answer 1

这两个实体之间有一个双向映射，这将在JSON序列化期间导致无限循环。

例如，您必须使用@JsonIgnore忽略其中一个边。

在这里阅读更多关于这个主题的信息：

https://www.baeldung.com/jackson-bidirectional-relationships-and-infinite-recursion

Answer 2

像下面一样使用@JsonIgnore。问题是无限的json调用正在通过json调用进行。要忽略这一点，请在多人关系中使用此注释。对我来说很好。

@ManyToOne//(fetch = FetchType.LAZY)
@JsonIgnore
private PriceListItemTest priceListItemsTest;

Answer 3

更改模型类，如下所示：

@Entity
@Table(name = "QP_PRICE_LIST_ITEMS")
public class PriceListItemTest implements Serializable {

    private static final long serialVersionUID = -748956247024967638L;

    @Basic
    @Column(name = "price_list_item_id")    
    private String priceListItemId;

    @Basic
    @Column(name = "pricing_uom_code")  
    private String pricingUOMCode; 

    @Basic
    @Column(name = "line_type_code")    
    private String lineTypeCode; 

    @Basic
    @Column(name = "primary_pricing_uom_flag")  
    private String primaryPricingUOMFlag;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "item_id")   
    private String itemId;

    @JsonManagedReference
    @OneToMany(mappedBy = "priceListItemsTest", cascade = CascadeType.ALL)
    private List<ItemDetailTest> itemDetailsTest;

    // getters and setters
}

和

@Entity
@Table(name = "egp_system_items_b")
public class ItemDetailTest implements Serializable {

    private static final long serialVersionUID = 8495817802073010928L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "inventory_item_id") 
    private String inventoryItemId; 

    @Basic
    @Column(name = "item_number")   
    private String itemNumber; 

    @Basic
    @Column(name = "organization_id")   
    private String organizationId;

    @JsonBackReference
    @ManyToOne
    @JoinColumn(name = "fk_item_id", nullable = false) // name of the foreign key column
    private PriceListItemTest priceListItemsTest;

    // getters and setters
}

在JoinColumn中，提供外键字段的实际名称。它应该可以工作，因为杰克逊会自动序列化。

对于许多推荐，你可以点击以下链接：链接1和链接2