Linq 获取投影内部子集合中的第一个对象
我拥有以下实体:Linq 获取投影内部子集合中的第一个对象,linq,entity-framework,Linq,Entity Framework,我拥有以下实体: public class Mark { public Int32 Id { get; set; } public DateTime Created { get; set; } public virtual ICollection<MarkLocalized> MarksLocalized { get; set; } } // Mark public class MarkLocalized { public Int32 Id { get; set;
public class Mark {
public Int32 Id { get; set; }
public DateTime Created { get; set; }
public virtual ICollection<MarkLocalized> MarksLocalized { get; set; }
} // Mark
public class MarkLocalized {
public Int32 Id { get; set; }
public String Culture { get; set; }
public String Name { get; set; }
public virtual Mark Mark { get; set; }
} // MarkLocalized
我尝试了以下方法:
Context context = new Context();
context.Marks
.SelectMany(x => x.MarksLocalized, (y, z) =>
new MarkModel {
Id = y.Id,
Name = z.Name,
Slug = z.Slug
});
但我只需要将标记本地化,即哪种文化等于给定的文化
我该怎么做
谢谢,,
米格尔您可以在
中的位置添加,选择多个:
Context context = new Context();
context.Marks
.SelectMany(x => x.MarksLocalized.Where(x => x.Culture == "en"), (y, z) =>
new MarkModel {
Id = y.Id,
Name = z.Name,
Slug = z.Slug
});
但语法查询应该更清楚:
from m in new Context.Marks
from l in m.MarksLocalized
where l.Culture == "en"
select new MarkModel { m.ID, m.Name, l.Slug }
编译器应将其转换为以下查询:
context.Marks
.SelectMany(x => x.MarksLocalized, (m, l) => new { m, l })
.Where(x => x.l.Culture == "en")
.Select(x => new MarkModel { x.m.ID, x.m.Name, x.l.Slug })
这将产生与第一个完全相同的结果。第三个选项看起来非常不错。。。我不知道我可以在SelectMany之外找到where,但它符合逻辑。。。非常感谢。
context.Marks
.SelectMany(x => x.MarksLocalized, (m, l) => new { m, l })
.Where(x => x.l.Culture == "en")
.Select(x => new MarkModel { x.m.ID, x.m.Name, x.l.Slug })