LINQ返回DISTINCT值

Question

我有一个LINQ to Entities查询，我想只返回TagID和TagName的唯一值。

代码：

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，仍然会返回重复的行，如下所示。如何确保只返回唯一的行？

[
    {
        "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

根据您的上一条评论，这是一个解决方案：

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
});