具有多个条件的 Linq @Where 子句

Question

这是我的导出用户界面

这是我的代码：

var wrlist = db.Tbl_WorkRequest.ToList().Where(c => c.WR_Status == wrstatus &&
                                                    (wrtype.Length != 0) &&
                                                    c.WR_Family == wrfamily &&
                                                    wrfamily.Length!=0)
                                        .Select(d => new {
                                            WR_Title = d.WR_Title.ToString(),
                                            WR_Type = d.WR_Type.ToString(),
                                            WR_Family = d.WR_Family.ToString(),
                                            WR_Status = d.WR_Status.ToString(),
                                            WR_LocationAsset = d.WR_LocationAsset.ToString(),
                                            WR_AssetName = d.WR_AssetName.ToString(),
                                            WR_Requestor = d.WR_Requestor.ToString()
                                        });

问题是如果我只在下拉列表中选择区域：家庭它会生成正确的列表。 但是当我选择 dropdownlist:family&status 时，它什么也没产生。

这是表：

Answer 1

我会更改您的代码以检查每个过滤条件并添加适当的过滤器，然后转换为列表：

var wrq = db.Tbl_WorkRequest.AsQueryable();
if (wrstatus.Length > 0)
    wrq = wrq.Where(wr => wr.WR_Status == wrstatus);
if (wrfamily.Length > 0)
    wrq = wrq.Where(wr => wr.WR_Family == wrfamily);

var wrlist = wrq.Select(d => new {
                    WR_Title = d.WR_Title.ToString(),
                    WR_Type = d.WR_Type.ToString(),
                    WR_Family = d.WR_Family.ToString(),
                    WR_Status = d.WR_Status.ToString(),
                    WR_LocationAsset = d.WR_LocationAsset.ToString(),
                    WR_AssetName = d.WR_AssetName.ToString(),
                    WR_Requestor = d.WR_Requestor.ToString()
                })
                .ToList();