我有一组数据和字典:
- 收集句柄学生数据
- 字典保存学生类(class)。
我想从字典中获取类(class)名称并将其作为类(class)名称放入。
private viod GenerateStudentDetails(Student studentData)
{
var courses = m_courses.GetCoursesDictionary(); // returns Dictionary<Guid,string>()
var studentDetails= from data in studentData
select new
{
FirstName = data.FirstName,
LastName = data.LastName,
Email = data.Email,
Mobile = data.Profile.Mobile,
City = data.Profile.City,
PostCode = data.Profile.PostCode,
CourseName = courses[data.Profile.CourseID ?? Guid.Empty]
};
}
"LINQ to Entities does not recognize the method 'System.String get_Item(System.Guid)' method, and this method cannot be translated into a store expression."
最佳答案
您可以尝试以下操作:
private viod GenerateStudentDetails(Student studentData)
{
var courses = m_courses.GetCoursesDictionary(); // returns Dictionary<Guid,string>()
var studentDetails= (from data in studentData
select new
{
FirstName = data.FirstName,
LastName = data.LastName,
Email = data.Email,
Mobile = data.Profile.Mobile,
City = data.Profile.City,
PostCode = data.Profile.PostCode,
CourseID = data.Profile.CourseID
}).AsEnumerable()
.Select(item=>new
{
FirstName = item.FirstName,
LastName = item.LastName,
Email = item.Email,
Mobile = item.Profile.Mobile,
City = item.Profile.City,
PostCode = item.Profile.PostCode,
CourseName = courses[item.Profile.CourseID ?? Guid.Empty]
});
}
What's the problem?
问题是您创建的匿名类型中的最后一个表达式,
CourseName = courses[data.Profile.CourseID ?? Guid.Empty]
不能出现在这个地方,因为它无法被正确翻译。所以你有这个选择。您可以从 studentData
中声明您想要的数据序列,然后将您想要的任何内容转换为我们创建的新匿名类型。
关于c# - 如何在 LINQ 查询中从字典获取值到新对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33750564/