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Cascade Delete

The following content heavily relies on the correct configuration of Navigation Properties, so please ensure you understand that first before proceeding!

Cascade delete only applies to OneToOne, OneToMany, and ManyToMany navigation properties. The Cascade Saving document has already explained this.

Cascade Delete Based on [Objects]

For example, objects retrieved using Include/IncludeMany queries can be cascade deleted using this method.

var repo = fsql.GetRepository<UserGroup>();
repo.DbContextOptions.EnableCascadeSave = true; // Key setting
repo.Insert(new UserGroup
{
    GroupName = "group01",
    Users = new List<User>
    {
        new User { Username = "admin01", Password = "pwd01", UserExt = new UserExt { Remark = "User Remark 01" } },
        new User { Username = "admin02", Password = "pwd02", UserExt = new UserExt { Remark = "User Remark 02" } },
        new User { Username = "admin03", Password = "pwd03", UserExt = new UserExt { Remark = "User Remark 03" } },
    }
}); // Cascade add test data
//INSERT INTO "usergroup"("groupname") VALUES('group01') RETURNING "id"
//INSERT INTO "user"("username", "password", "groupid") VALUES('admin01', 'pwd01', 1), ('admin02', 'pwd02', 1), ('admin03', 'pwd03', 1) RETURNING "id" as "Id", "username" as "Username", "password" as "Password", "groupid" as "GroupId"
//INSERT INTO "userext"("userid", "remark") VALUES(3, 'User Remark 01'), (4, 'User Remark 02'), (5, 'User Remark 03')

var groups = repo.Select
    .IncludeMany(a => a.Users, 
        then => then.Include(b => b.UserExt))
    .ToList();
repo.Delete(groups); // Cascade delete, recursively traverses group OneToOne/OneToMany/ManyToMany navigation properties
//DELETE FROM "userext" WHERE ("userid" IN (3,4,5))
//DELETE FROM "user" WHERE ("id" IN (3,4,5))
//DELETE FROM "usergroup" WHERE ("id" = 1)

Cascade Delete Based on [Database]

Based on the configured navigation properties, recursively delete the corresponding data for OneToOne/OneToMany/ManyToMany and return the deleted data. This feature does not rely on database foreign keys.

var repo = fsql.GetRepository<UserGroup>();
var ret = repo.DeleteCascadeByDatabase(a => a.Id == 1);
//SELECT a."id", a."username", a."password", a."groupid" FROM "user" a WHERE (a."groupid" = 1)
//SELECT a."userid", a."remark" FROM "userext" a WHERE (a."userid" IN (3,4,5))
//DELETE FROM "userext" WHERE ("userid" IN (3,4,5))
//DELETE FROM "user" WHERE ("id" IN (3,4,5))
//DELETE FROM "usergroup" WHERE ("id" = 1)

//ret   Count = 7 System.Collections.Generic.List<object>
//  [0] {UserExt} object {UserExt}
//  [1] {UserExt} object {UserExt}
//  [2] {UserExt} object {UserExt}
//  [3] {User}     object {User}
//  [4] {User}     object {User}
//  [5] {User}     object {User}
//  [6] {UserGroup} object {UserGroup}

public class UserGroup
{
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string GroupName { get; set; }

    [Navigate(nameof(User.GroupId))]
    public List<User> Users { get; set; }
}
public class User
{
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
    public int GroupId { get; set; }

    [Navigate(nameof(Id))]
    public UserExt UserExt { get; set; }
}
public class UserExt
{
    [Column(IsPrimary = true)]
    public int UserId { get; set; }
    public string Remark { get; set; }

    [Navigate(nameof(UserId))]
    public User User { get; set; }
}