一、使用仓储的好处

• 1.提高CRUD接口复用性
• 2.解耦业务逻辑（BLL）和增删改查（CRUD），换ORM特别方便，不需要改应用层，直接改仓储层
• 3.做复杂查询
• 4.事务支持

二、Demo

public class BookRepository : IBookRepository, ITransientDependency  //接口依赖注入
{
    private readonly IFreeSql _fsql;

    public BookRepository(IFreeSql fsql)
    {
        _fsql = fsql;
    }

    /// <summary>
    /// 获取FreeSql
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    public IFreeSql GetFreeSql()
    {
        return _fsql;
    }

    /// <summary>
    /// 分页查询：Book
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    [HttpPost]
    [Route(nameof(GetBookPageListAsync))]
    public async Task<IPageList<BookDto>> GetBookPageListAsync(BookSerachInput input)
    {
        var output = new PageList<BookDto>(new List<BookDto>(), input.PageIndex, input.maxResultCount);
        if (false)
        {
            return output;//不符合要求，返回空数据
        }
        var fsql = GetFreeSql();
        //查表
        var queryList = await fsql.Select<Book>()
                        .Where(x => x.TimePoint.Between(input.StartTime, input.EndTime))
                        .WhereIf(input.StationCodes.Any(), x => input.StationCodes.Contains(x.CityCode))
                        .OrderBy(!string.IsNullOrEmpty(input.orderby), input.orderby)
                        .Page(input.PageIndex, input.maxResultCount)
                        .Count(out var totalCount)
                        .ToListAsync();
        //映射结果
        var dtoList = _objectMapper.Map<List<Book>, List<BookDto>>(queryList);
        return new PageList<BookDto>(dtoList, input.PageIndex, input.maxResultCount, totalCount);
    }

    /// <summary>
    /// Book 单一实体 修改
    /// </summary>
    public async Task<bool> UpdateBookAsync(BookDto input)
    {
        var fsql = GetFreeSql();
        return fsql.Update<BookDto>(input).ExecuteAffrows() != 0;
    }

    /// <summary>
    /// Book 单一实体 保存
    /// </summary>
    public async Task<bool> SaveBookAsync(BookDto input)
    {
        var fsql = GetFreeSql();
        bool isExist = await fsql.Select<Book>().AnyAsync(x => x.Id == input.Id);//【根据实际修改】根据（联合）主键确定唯一性
        if (isExist)
        {
            return await UpdateBookAsync(input);
        }
        return await InsertBookAsync(input);
    }

    /// <summary>
    /// Book 单一实体 插入
    /// </summary>
    public async Task<bool> InsertBookAsync(BookDto input)
    {
        var fsql = GetFreeSql();
        return fsql.Insert(input).ExecuteAffrows() != 0;
    }

    /// <summary>
    /// Book 单一实体 删除
    /// </summary>
    public async Task<bool> DeleteBookAsync(BookDto input)
    {
        var fsql = GetFreeSql();
        return fsql.Delete<BookDto>(input).ExecuteAffrows() != 0;
    }

    /// <summary>
    /// Book 列表 保存
    /// </summary>
    public async Task<bool> SaveBookListAsync(List<BookDto> inputList)
    {
        bool result = true;
        var fsql = GetFreeSql();

        //获取输入主键
        var inputKeyList = inputList.Select(x => x.Id ).Distinct().ToList();

        //根据输入主键获取已存在实体
        var existList = await fsql.Select<Book>().Where(x => inputKeyList.Contains(x.Id)).ToListAsync();

        //获取已存在实体的主键列表
        var existKeyList = existList.Select(x => x.Id).Distinct().ToList();

        // 获取更新列表和插入列表
        var updateList = inputList.Where(x => existKeyList.Contains(x.Id)).ToList();
        var insertList = inputList.Where(x => !existKeyList.Contains(x.Id)).ToList();

        /*联合主键：
            //获取输入主键
            var inputKeyList = inputList.Select(x => new { x.Id , x.BookName }).Distinct().ToList();
            //根据输入主键获取已存在实体
            var existList = await fsql.Select<Book>().Where(x=> inputKeyList.Any(key=>key.Id == x.Id && key.BookName == x.BookName)).ToListAsync();
            //获取已存在实体的主键列表
            var existKeyList = existList.Select(x => new { x.Id, x.BookName }).Distinct().ToList();
            //获取更新列表和插入列表
            var updateList = inputList.Where(x => existKeyList.Contains(new { x.Id, x.BookName })).ToList();
            var insertList = inputList.Where(x => !existKeyList.Contains(new { x.Id, x.BookName })).ToList();
       */

        // 使用批量更新和批量插入方法
        bool updateSuccess = await UpdateBookListAsync(updateList);  // 批量更新
        bool insertSuccess = await InsertBookListAsync(insertList);  // 批量插入

        return updateSuccess && insertSuccess; // 返回是否全部成功
    }

    /// <summary>
    /// Book 列表 修改
    /// </summary>
    public async Task<bool> UpdateBookListAsync(List<BookDto> input)
    {
        var fsql = GetFreeSql();
        return fsql.Update<BookDto>(input).ExecuteAffrows() != 0;
    }

    /// <summary>
    /// Book 列表 插入
    /// </summary>
    public async Task<bool> InsertBookListAsync(List<BookDto> input)
    {
        var fsql = GetFreeSql();
        return fsql.Insert(input).ExecuteAffrows() != 0;
    }

    /// <summary>
    /// Book 列表 删除
    /// </summary>
    public async Task<bool> DeleteBookListAsync(List<BookDto> input)
    {
        var fsql = GetFreeSql();
        return fsql.Delete<BookDto>(input).ExecuteAffrows() != 0;
    }

}