使用复合键进行多对多自引用

Question

我有以下型号

type TenantUser struct {
    TenantID  uint      `json:"tenantId" gorm:"primaryKey; uniqueIndex:idx_name_and_tenant; uniqueIndex:idx_email_and_tenant"`
    UserID    uuid.UUID `json:"-" gorm:"primaryKey; type:uuid"`
    ...
    Visited  []*TenantUser `json:"visited" gorm:"many2many:visitors; foreignKey:TenantID,UserID; references:TenantID,UserID; joinForeignKey:visitor_tenant_id,visitor_user_id; joinReferences:visitee_tenant_id,visitee_user_id"`
    Visitors []*TenantUser `json:"visitors" gorm:"many2many:visitors; foreignKey:TenantID,UserID; references:TenantID,UserID; joinForeignKey:visitee_tenant_id,visitee_user_id; joinReferences:visitor_tenant_id,visitor_user_id"`
}

这会生成以下 sql

create table visitors
(
    visitor_tenant_id bigint not null unique,
    visitor_user_id   uuid   not null,
    visitee_tenant_id bigint not null unique,
    visitee_user_id   uuid   not null,
    primary key (visitor_tenant_id, visitor_user_id, visitee_tenant_id, visitee_user_id),
    constraint fk_visitors_tenant_user foreign key (visitor_tenant_id, visitor_user_id) references tenant_users,
    constraint fk_visitors_visited foreign key (visitee_tenant_id, visitee_user_id) references tenant_users
);

我不明白为什么

visitor_tenant_id

和

visitee_tenant_id

被定义为唯一的。但更重要的是，我该如何预防？

如果我执行如下代码，并且具有不同的访问者，则仅添加第一个访问者。再做一遍就没有任何作用。它甚至没有给出错误。如果我手动从数据库中删除唯一索引，一切都会按预期进行。

db.Model(&visitee.TenantUser).Association("Visitors").Append([]*model.TenantUser{visitor})

知道发生了什么事吗？

Answer 1

从

uniqueIndex

结构中的

TenantID

字段中删除

TenantUser

标签，然后重新生成数据库架构。

type TenantUser struct {
    TenantID  uint      `json:"tenantId" gorm:"primaryKey"`
    UserID    uuid.UUID `json:"-" gorm:"primaryKey; type:uuid"`
    ...
    Visited  []*TenantUser `json:"visited" gorm:"many2many:visitors; foreignKey:TenantID,UserID; references:TenantID,UserID; joinForeignKey:visitor_tenant_id,visitor_user_id; joinReferences:visitee_tenant_id,visitee_user_id"`
    Visitors []*TenantUser `json:"visitors" gorm:"many2many:visitors; foreignKey:TenantID,UserID; references:TenantID,UserID; joinForeignKey:visitee_tenant_id,visitee_user_id; joinReferences:visitor_tenant_id,visitor_user_id"`
}