实体框架核心级联删除错误答案

【问题标题】：Entity Framework Core Cascade Delete Error实体框架核心级联删除错误
【发布时间】：2020-02-10 15:50:22
【问题描述】：

虽然在外键“FK_TeamMember_Teams_TeamId”上已设置为 on-delete:“ReferentialAction.Restrict”，但在尝试从 TeamMember 表中删除记录时会出现以下错误。你能帮我解决这个错误吗？

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. 
See the inner exception for details.
---> Microsoft.Data.SqlClient.SqlException (0x80131904): The DELETE statement conflicted with the
REFERENCE constraint "FK_TeamMember_Teams_TeamId". The conflict occurred in database "mot", table 
"dbo.TeamMember", column 'TeamId'. The statement has been terminated.

以下是迁移代码块

  migrationBuilder.CreateTable(
            name: "TeamMember",
            columns: table => new
            {
                Id = table.Column<Guid>(nullable: false),
                MarketingOfficerId = table.Column<Guid>(nullable: false),
                TeamId = table.Column<Guid>(nullable: true)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_TeamMember", x => x.Id);
                table.ForeignKey(
                    name: "FK_TeamMember_Employees_MarketingOfficerId",
                    column: x => x.MarketingOfficerId,
                    principalTable: "Employees",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Cascade);
                table.ForeignKey(
                    name: "FK_TeamMember_Teams_TeamId",
                    column: x => x.TeamId,
                    principalTable: "Teams",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.Restrict);
            });

OnModelCreating 方法我也使用了以下方法。

modelBuilder.Entity<Team>()
       .HasMany(i => i.TeamMembers)
       .WithOne(i=>i.Team)
       .OnDelete(DeleteBehavior.Restrict);

谢谢

【问题讨论】：

您使用的是哪个版本的 EF Core？
实体框架核心 v3.1.1

标签： asp.net entity-framework entity-framework-core asp.net-core-webapi webapi

【解决方案1】：

我认为这种行为是正确的，因为当主表删除一条记录时，它应该删除明细表中的相关记录。保留它没有意义。数据将是多余的。但是，如果我们想制作这样的场景，尽管我们在 migration.cs 中将 CascadeDelete 设置为 Restrict，但它不会按预期工作。以下文章将有助于理解这些行为。

https://docs.microsoft.com/en-us/ef/core/saving/cascade-delete

【讨论】：