IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.Sqlite, 
        @"Data Source=|DataDirectory|\document.db;Pooling=true;Max Pool Size=10")
    .UseAutoSyncStructure(true) //自动同步实体结构到数据库
    .Build();

class Song {
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string Title { get; set; }
    public string Url { get; set; }
    public DateTime CreateTime { get; set; }

    public virtual ICollection<Tag> Tags { get; set; }
}
class Song_tag {
    public int Song_id { get; set; }
    public virtual Song Song { get; set; }

    public int Tag_id { get; set; }
    public virtual Tag Tag { get; set; }
}
class Tag {
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string Name { get; set; }

    public int? Parent_id { get; set; }
    public virtual Tag Parent { get; set; }

    public virtual ICollection<Song> Songs { get; set; }
    public virtual ICollection<Tag> Tags { get; set; }
}

//OneToOne、ManyToOne
var t0 = fsql.Select<Tag>()
    .Where(a => a.Parent.Parent.Name == "粤语")
    .IncludeMany(a => a.Tags, then => then.Where(sub => sub.Name == "xxx"))
    .ToList();

//OneToMany
var t1 = fsql.Select<Tag>()
    .Where(a => a.Tags.AsSelect().Any(t => t.Parent.Id == 10))
    .ToList();

//ManyToMany
var t2 = fsql.Select<Song>()
    .Where(s => s.Tags.AsSelect().Any(t => t.Name == "国语"))
    .IncludeMany(a => a.Tags, then => then.Where(sub => sub.Name == "xxx"))
    .ToList();

//Other
var t3 = fsql.Select<Xxx>()
    .Where(a => a.IsDelete == 0)
    .WhereIf(keyword != null, a => a.UserName.Contains(keyword))
    .WhereIf(role_id > 0, a => a.RoleId == role_id)
    .Where(a => a.Nodes.AsSelect().Any(t => t.Parent.Id == t.UserId))
    .Count(out var total)
    .Page(page, size)
    .OrderByDescending(a => a.Id)
    .ToList()

var t3 = fsql.Select<Song>()
    .Where(a => new[] { 1, 2, 3 }.Contains(a.Id))
    .ToList();

var t4 = fsql.Select<Song>()
    .Where(a => a.CreateTime.Date == DateTime.Now.Date)
    .ToList();

var t5 = fsql.Select<Song>()
    .OrderBy(a => Guid.NewGuid())
    .Limit(1)
    .ToList();

using (var uow = fsql.CreateUnitOfWork()) {
    var repo1 = uow.GetRepository<Song, int>();
    var repo2 = uow.GetRepository<Tag, int>();

    await repo1.InsertAsync(new Song());
    await repo2.InsertAsync(new Tag());
    uow.Commit();
}

using (var ctx = new fsql.CreateDbContext()) {
    var songs = ctx.Set<Song>();
    var tags = ctx.Set<Tag>();

    var tag = new Tag {
        Name = "testaddsublist",
        Tags = new[] {
            new Tag { Name = "sub1" },
            new Tag { Name = "sub2" },
            new Tag {
                Name = "sub3",
                Tags = new[] {
                    new Tag { Name = "sub3_01" }
                }
            }
        }
    };
    //tags.Add(tag);
    ctx.Add(tag);
    await ctx.SaveChangesAsync();
}

public void ConfigureServices(IServiceCollection services) {
    services.AddSingleton<IFreeSql>(Fsql);
    services.AddFreeRepository(filter => filter
        .Apply<ISoftDelete>("SoftDelete", a => a.IsDeleted == false)
        .Apply<ITenant>("Tenant", a => a.TenantId == 1)
        ,
        this.GetType().Assembly
    );
}

var repoq = fsql.GetRepository<Song, int>();

using (repo1.DataFilter.Disable("Tenant")) {
    //Tenant Invalid
}
//Tenant restore