LINQ返回DISTINCT值

Question

我有一個LINQ to Entities查詢，我只想返回TagID和TagName的唯一值。

代碼：

var tags = (from t in _dbContext.TaskRecordDetails.ToList() 
         join tag in _dbContext.Tags on t.TagName equals tag.TagName 
         where t.Period == period 
         select new TagDTO() 
         { 
          TagID = tag.TagID, 
          TagName = tag.TagName 
         }); 

      return tags.Distinct<TagDTO>(); 

但是，重複行仍返回如下。我如何確保只返回唯一的行？

[ 
    { 
     "TagID": 1, 
     "TagName": "Level 1", 
     "TagDescription": null, 
     "IsActive": false 
    }, 
    { 
     "TagID": 2, 
     "TagName": "Level 3", 
     "TagDescription": null, 
     "IsActive": false 
    }, 
    { 
     "TagID": 3, 
     "TagName": "Level 5", 
     "TagDescription": null, 
     "IsActive": false 
    }, 
    { 
     "TagID": 1, 
     "TagName": "Level 1", 
     "TagDescription": null, 
     "IsActive": false 
    }, 
    { 
     "TagID": 2, 
     "TagName": "Level 3", 
     "TagDescription": null, 
     "IsActive": false 
    } 
] 

Answer 1

根據您最後的評論，這裏是一個解決方案：

var tags = (from t in _dbContext.TaskRecordDetails 
      join tag in _dbContext.Tags on t.TagName equals tag.TagName 
      where t.Period == period 
      select tag).Distinct().ToList(); 

return tags.select(x => new TagDTO 
{ 
    TagID = x.TagID, 
    TagName = x.TagName 
});