JPA休眠中一对一关系中的外键约束子级

Question

好吧，我在JPA上使用了Spring Boot，并且我有一个实体，该实体包含与下面描述的子代相同的实体，下面介绍如何使用RuleCondition类型的nextCondition：

@Entity @Table(name = "EDITOR_REGRA_CONDICAO") 
public class RuleCondition implements Serializable {

@GenericGenerator(
        name = "ruleConditionSequenceGenerator",
        strategy = "org.hibernate.id.enhanced.SequenceStyleGenerator",
        parameters = {
                @Parameter(name = "sequence_name", value = "SEQ_RULE_CONDITION"),
                @Parameter(name = "initial_value", value = "1"),
                @Parameter(name = "increment_size", value = "1")
        })
@GeneratedValue(generator = "ruleConditionSequenceGenerator")
@Id
private Long id;

@OneToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "field", nullable = false)
private Field field;

@Column
private String value;

@OneToOne(fetch = FetchType.EAGER, optional = false)
@JoinColumn(name = "operator", nullable = false)
private RuleOperator ruleOperator;

@OneToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "connector")
private RuleConnector ruleConnector;

@OneToOne(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
@JoinColumn(name = "next_condition")
private RuleCondition nextCondition;

这是规则条件控制器

@RequestMapping(value = "/rule", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE, consumes = MediaType.APPLICATION_JSON_VALUE)
public Rule newRule(@RequestParam("layout") Long layoutId, @RequestBody Rule rule) {
    return ruleManager.newRule(rule,layoutId);
}

最后确定的是负责管理规则条件操作的类：

 public Rule newRule(@Nonnull final Rule rule, @Nonnull final Long layoutId) {

    RuleType ruleType = ruleService.getRuleType(rule.getRuleType().getIdentifier());

    saveConditions(rule.getCondition());

    rule.setRuleType(ruleType);

    Rule savedRule = ruleService.saveRule(rule);

    layoutManager.addRule(savedRule, layoutId);

    return savedRule;
}

@Transactional(propagation = Propagation.REQUIRES_NEW)
private void saveConditions(RuleCondition ruleCondition) {

    RuleConnector ruleConnector;
    RuleOperator ruleOperator;

    if (ruleCondition == null) {
        return;
    }

    if (ruleCondition.getNextCondition() != null) {
        saveConditions(ruleCondition.getNextCondition());
    }

    if (ruleCondition.getRuleConnector() != null) {
        ruleConnector = ruleService.getRuleConnector(ruleCondition.getRuleConnector().getIdentifier());
        ruleCondition.setRuleConnector(ruleConnector);
    }

    if (ruleCondition.getRuleOperator() != null) {
        ruleOperator = ruleService.getRuleOperator(ruleCondition.getRuleOperator().getIdentifier());
        ruleCondition.setRuleOperator(ruleOperator);
    }

    if (ruleCondition.getField() != null) {
        Field field = fieldManager.getFieldByName(ruleCondition.getField().getName());
        ruleCondition.setField(field);
    }

    ruleService.saveCondition(ruleCondition);

}

当我保留数据时，遇到以下错误：

唯一索引或主键冲突：“ UK_QG4N8FT2CPEX15N36TM2SRXPN_INDEX_1 ON PUBLIC.EDITOR_REGRA_CONDICAO（FIELD）值（1、1）”； SQL语句：插入到editor_regra_condicao（字段，next_condition，连接器，运算符，值，id）值（？，？，？，？，？，？）[23505-193]

Answer 1

从上下文，似乎在RuleCondition插入链接到Field已经有一个RuleCondition链接到它。

在one-to-one关系中，这是不允许的（顾名思义，此类关系仅限于单个关系）

要解决这个问题

对字段使用many-to-one关系：

@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "field", nullable = false)
private Field field;

或者，在每次保存之前，请确保没有链接到已经有RuleCondition链接到的字段。