Question

好的，我在下面写了LINQ to Entities查询（足够接近我下面显示的c＃查询）

var itemss = filteredstudents
.Where(x => x.SubjectTypes.Any(y => y.SubjectItem.Any(z => z.Name  == value1))).ToList();

仍然没什么问题，因为当SubjectItem类型有两个元素且其中一个与value1匹配时。它仍然返回两者。它应该只返回匹配的记录。我知道问题出在Any上，但不确定Any会替换为什么？

foreach (StudentDTO student in filteredstudents)
{
    bool valid = true;
    foreach (SubjectTypes subjectType in student.SubjectTypes)
    {
        string value1 = subjectType.SubjectItem.Select(x => x.value1).First();
        Guid StId = _context.Items.Where(x => x.Name == value1).FirstOrDefault();

        if (StId != null)
            valid = true;
        else
        {
            valid = false;
            _log("create log");
        }
    }
    if (valid)
        filteredstudentsWithUnits.Add(student);
}

示例输入

{"Name":"ABC",
"Age":12,
,"SubjectTypes":
[
{"Id":"1","Description":""Description","SubjectItem":[{"Id":"1","Marks":12,"Name":"aaa"}]},
{"Id":"1","Description":""Description","SubjectItem":[{"Id":"1","Marks":12,"Name":"aaa"}]},
{"Id":"1","Description":""Description","SubjectItem":[{"Id":"1","Marks":12,"Name":"bbb"}]}
]
}

预期输出

{"Name":"ABC",
"Age":12,
,"SubjectTypes":
[
{"Id":"1","Description":""Description","SubjectItem":[{"Id":"1","Marks":12,"Name":"aaa"}]},
{"Id":"1","Description":""Description","SubjectItem":[{"Id":"1","Marks":12,"Name":"aaa"}]},

]
}

Answer 1

您可以先使用.Where过滤列表，然后使用.Select投影到仅包含所需数据的新集合。以下内容可能有效：

var itemss = filteredstudents
    .Where(s => s.SubjectTypes.Any(st => st.SubjectItem.Any(si => si.Name  == value1)))
    .Select(s => new StudentDTO
    {
        Name = s.Name,
        Age = s.Age,
        SubjectTypes = s.SubjectTypes.Where(st => st.SubjectItem.Any(si => si.Name  == value1))
            .Select(st => new SubjectType
            {
                Id = st.Id,
                Description = st.Description,
                SubjectItem = st.SubjectItem.Where(si => si.Name == value1).ToList()
            }).ToList()
    })
    .ToList();

Answer 2

这将解决您的问题，但可能有更好的方法，我也省略了一些属性，如您需要添加的ID和标记。

var items = filteredstudents.Select(s => new StudentDTO
{
    Name = s.Name,
    SubjectTypes = s.SubjectTypes.Select(st => new SubjectType
    {
        Description = st.Description,
        SubjectItems = st.SubjectItems.Where(si => si.Name == "AAA").ToList()
    }).Where(x => x.SubjectItems.Count > 0).ToList()
});

Answer 3

以下逻辑可以帮助您仅过滤嵌套列表。

例如：

考虑以下类结构：

class EntityName { int i; string xx; List<SubEntity> subEntityName; }

然后，仅过滤subEntity这样的详细信息。

objEntity.SubEntityName = objEntity.SubEntityName.Where(x=>x.attrubute== "")"

Linq过滤嵌套列表

3 个答案: