不会持久化支持实体到哈希映射的转换 [英] Does blaze persistence support entity to hashmap conversion

问题描述

出色的持久性支持实体到键值对的转换，EntityView字段的名称也可以与实际Entity的名称不同

Does blaze persistence support conversion of entity to key value pairs, also can EntityView fields have a different name than that of actual Entity

@Entity
@Table(name = "users")
public class User {

  @Column
  private String name;

  @OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
  private Set<UserPropertyValue> userPropertyValues = new HashSet<>();

}

@Entity
@Table(name = "user_property_values")
public class UserPropertyValue {

  @Column
  private String value;

  @ManyToOne
  JoinColumn(name = "properties_id")
  private Property property;
}

@Entity
@Table(name = "properties")
public class Property {
  @Id
  private Long id;
  
  @Column
  private String name;
}

我想要EntityView这样的东西.

I Would want the EntityView something like this.

@EntityView(User.class)
interface UserView {
  private String getUserName();
  private HashMap<String, String>  userPropertyValues();
}

基本上名称是此处的用户名，并且 userPropertyValues 应该是包含以下内容的HashMap:

Basically name is the username here and userPropertyValues should be HashMap containing:

1. 键作为属性-> 名称
2. 值作为 PropertyValues -> 值

1. key as the Property -> name
2. value as PropertyValues -> value

它是否还有助于创建自定义转换器，例如我想将LocalDateTime更改为具有各种不同格式/样式的String?

Also does it help create custom converters, say I want to change LocalDateTime to String with various different format/pattern ?

推荐答案

当然，您可以使用@Mapping批注指定JPQL.Next映射，如下所示:

Sure, you can use the @Mapping annotation to specify a JPQL.Next mapping which could look like the following:

@EntityView(User.class)
interface UserView {
  @Mapping("name")
  String getUserName();
  Set<UserPropertyValueView> getUserPropertyValues();
}
@EntityView(UserPropertyValue.class)
interface UserPropertyValueView {
  @Mapping("property.name")
  String getPropertyName();
  String getValue();
}

如果您真的想要一张地图，也可以使用以下内容:

If you really want a map, you could also use the following:

@EntityView(User.class)
public abstract class UserView {

  private final Map<String, String> values;

  public UserView(@Mapping("userPropertyValues") Set<UserPropertyValueView> values) {
    this.values = values.stream().collect(Collectors.toMap(UserPropertyValueView::getPropertyName, UserPropertyValueView::getValue))
  }

  @Mapping("name")
  public abstract String getUserName();
  public Map<String, String> getUserPropertyValues() {
    return values;
  }
}
@EntityView(UserPropertyValue.class)
interface UserPropertyValueView {
  @Mapping("property.name")
  String getPropertyName();
  String getValue();
}

通过注释映射地图键将在目前正在开发的最终1.5.0版本中引入: https://github.com/Blazebit/blaze-persistence/issues/401

Mapping map keys through an annotation will be introduced in the final 1.5.0 release which is currently being worked on: https://github.com/Blazebit/blaze-persistence/issues/401

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