如何使用 Spring Boot 为嵌套实体配置 Jackson 反序列化器

Question

考虑以下实体：

package br.com.investors.domain.endereco;

import com.google.common.base.Objects;
import com.google.common.base.Strings;
import com.google.common.collect.ComparisonChain;
import org.hibernate.validator.constraints.NotBlank;

import javax.persistence.*;
import java.io.Serializable;

import static com.google.common.base.Preconditions.checkArgument;
import static javax.persistence.GenerationType.SEQUENCE;

@Entity
public class Regiao implements Serializable, Comparable<Regiao> {

    @Id
    @GeneratedValue(strategy = SEQUENCE)
    private Long id;

    @Version
    private Long version;

    @NotBlank
    @Column(length = 100, unique = true)
    private String nome = "";

    Regiao() {}

    public Regiao(String nome) {
        checkArgument(!Strings.isNullOrEmpty(nome), "Nome não pode ser vazio");
        this.nome = nome;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Regiao) {
            Regiao o = (Regiao) obj;
            return Objects.equal(this.nome, o.nome);
        }
        return false;
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(nome);
    }

    @Override
    public int compareTo(Regiao o) {
        return ComparisonChain.start()
                .compare(this.nome, o.nome)
                .result();
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(getClass()).add("nome", nome).toString();
    }

    public Long getId() {
        return id;
    }

    public Long getVersion() {
        return version;
    }

    public String getNome() {
        return nome;
    }
}

和

package br.com.investors.domain.endereco;

import com.google.common.base.Objects;
import com.google.common.base.Strings;
import com.google.common.collect.ComparisonChain;
import org.hibernate.validator.constraints.NotBlank;

import javax.persistence.*;
import javax.validation.constraints.NotNull;
import java.io.Serializable;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static javax.persistence.GenerationType.SEQUENCE;

@Entity
public class Cidade implements Serializable, Comparable<Cidade> {

    @Id
    @GeneratedValue(strategy = SEQUENCE)
    private Long id;

    @Version
    private Long version;

    @NotBlank
    @Column(length = 100, unique = true)
    private String nome = "";

    @NotNull
    @ManyToOne
    private Regiao regiao;

    @NotNull
    @ManyToOne
    private Estado estado;

    Cidade() {}

    public Cidade(String nome, Regiao regiao, Estado estado) {
        checkArgument(!Strings.isNullOrEmpty(nome), "Nome não pode ser vazio");
        checkNotNull(regiao, "Região não pode ser nulo");
        checkNotNull(estado, "Estado não pode ser nulo");

        this.nome = nome;
        this.regiao = regiao;
        this.estado = estado;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof Cidade) {
            Cidade o = (Cidade) obj;
            return Objects.equal(this.nome, o.nome) &&
                    Objects.equal(this.estado, o.estado) &&
                    Objects.equal(this.regiao, o.regiao);
        }
        return false;
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(nome, regiao, estado);
    }

    @Override
    public int compareTo(Cidade o) {
        return ComparisonChain.start()
                .compare(this.estado, o.estado)
                .compare(this.regiao, o.regiao)
                .compare(this.nome, o.nome)
                .result();
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(getClass()).add("nome", nome).add("regiao", regiao).add("estado", estado).toString();
    }

    public Long getId() {
        return id;
    }

    public Long getVersion() {
        return version;
    }

    public String getNome() {
        return nome;
    }

    public Regiao getRegiao() {
        return regiao;
    }

    public Estado getEstado() {
        return estado;
    }
}

我正在尝试 POST 一个 JSON 到一个 RestController

@RequestMapping(value = "/cidades", method = POST, consumes = APPLICATION_JSON_VALUE)
void inserir(@RequestBody Cidade cidade) {
    repository.save(cidade);
}

我正在使用 Spring 引导的默认配置来序列化和反序列化对象。

如果我 post 像这样 JSON，它工作正常：

{
    "nome": "Cidade",
    "regiao": "/10"
}

但我需要 post 一个 JSON 这样的：

{
    "nome": "Cidade",
    "regiao": {
        "id": 10,
        "version": 0,
        "nome": "regiao"
    }
}

如果我这样做，我会得到错误

{
    "timestamp": "2015-04-02",
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
    "message": "Could not read JSON: Template must not be null or empty! (through reference chain: br.com.investors.domain.endereco.Cidade[\"regiao\"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Template must not be null or empty! (through reference chain: br.com.investors.domain.endereco.Cidade[\"regiao\"])",
    "path": "/cidades/"
}

做一些调试，我发现 Jackson 试图从 posted 对象的 "regiao" 属性创建一个 URI，等待像 "/{id 这样的字符串模板}”。我正在谷歌搜索，但找不到正确的答案。

我在 Whosebug 上看到了一些相关问题，但 none 对我有用。

大家能说说这是怎么回事吗？

我认为这只是一种配置，但不知道如何或在哪里。

我也在尝试避免自定义序列化器和反序列化器。

编辑：

如果我 POST 一个 JSON 只有嵌套实体的 id，像这样：

{
  "nome": "Cidade",
  "estado": "10",
  "regiao": "10"
}

我收到这条消息：

{
    "timestamp": "2015-04-07",
    "status": 400,
    "error": "Bad Request",
    "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
    "message": "Could not read JSON: Failed to convert from type java.net.URI to type br.com.investors.domain.endereco.Estado for value '10'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 10. Is it local or remote? Only local URIs are resolvable. (through reference chain: br.com.investors.domain.endereco.Cidade[\"estado\"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Failed to convert from type java.net.URI to type br.com.investors.domain.endereco.Estado for value '10'; nested exception is java.lang.IllegalArgumentException: Cannot resolve URI 10. Is it local or remote? Only local URIs are resolvable. (through reference chain: br.com.investors.domain.endereco.Cidade[\"estado\"])",
    "path": "/cidades"
}

正如我所见，发送嵌套实体的正确方式类似于 "regiao"：“/10”，我在我的 Javascript 中对此进行了硬编码以解决问题：

function(item) {
    item.regiao = "/" + item.regiao.id; //OMG
    item.estado = "/" + item.estado.id; //OMG!!

    if (item.id) {
        return $http.put('/cidades/' + item.id, item);
    } else {
        return $http.post('/cidades', item);
    }
}

它有效，但很糟糕。如何在 Javascript 或配置 Jackson 中解决此问题？

阅读了一些文档，与 UriToEntityConverter 有一些关系，但仍然不知道配置它的正确方法。

谢谢。

Answer 1

您可以像这样在您的实体上使用@JsonIgnoreProperties(ignoreUnknown = true) 注释class。

@Entity
@JsonIgnoreProperties(ignoreUnknown = true)
public class Area implements Serializable, CompanyAware, IdentifiableModel<Long> {
private static long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id = 0l;
@NotNull
@NotEmpty
@Column(nullable = false, unique = true)
private String name;
@NotNull
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(nullable = false)
private Region region;
private boolean active = true;

@ManyToOne
@JoinColumn(updatable = false)
private Company company;

public Long getId() {
    return id;
}

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

@Override
public int hashCode() {
    int hash = 0;
    hash += (getId() != null ? getId().hashCode() : 0);
    return hash;
}

@Override
public boolean equals(Object object) {
    // TODO: Warning - this method won't work in the case the id fields are not set
    if (!(object instanceof Area)) {
        return false;
    }
    Area other = (Area) object;
    if ((this.getId() == null && other.getId() != null) || (this.getId() != null && !this.id.equals(other.id))) {
        return false;
    }
    return true;
}

@Override
public String toString() {
    return "Area[ id=" + getId() + " ]";
}

/**
 * @return the name
 */
public String getName() {
    return name;
}

/**
 * @param name the name to set
 */
public void setName(String name) {
    this.name = name;
}

/**
 * @return the region
 */
public Region getRegion() {
    return region;
}

/**
 * @param region the region to set
 */
public void setRegion(Region region) {
    this.region = region;
}

/**
 * @return the active
 */
public boolean isActive() {
    return active;
}

/**
 * @param active the active to set
 */
public void setActive(boolean active) {
    this.active = active;
}

/**
 * @return the company
 */
public Company getCompany() {
    return company;
}

/**
 * @param company the company to set
 */
public void setCompany(Company company) {
    this.company = company;
} 
}

也许能解决您的问题。它将忽略 json 对象中未知的缺失字段。它将仅使用 json 对象中的可用字段并忽略未知字段。

Answer 2

我用 EstadoRepository 和 RegiaoRepository 上的 @RestResource(exported = false) 注释解决了它类。

它 "hides" 来自 spring 的回购，当它自动配置端点和东西时...

如何使用 Spring Boot 为嵌套实体配置 Jackson 反序列化器

How to configure Jackson deserializer for nested entites with Spring Boot

java

json

jackson

deserialization

spring-boot