如何在单个语句中加载两个导航属性，以避免数据库往返（如果有）

Question

What i want is to load two navigation property in my class through database context using entity framework...the way I can do it with Include method... And does it incur me two round trips or not to the db...

Note: I dont want to load it with with EF Context's Include method

Currently I'm doing it this way

db.Entry(category).Reference(p => p.Section).Load(); 
db.Entry(category).Collection("SubCategories").Load();

I want to load this in one statement

Answer 1

You can do this in one trip using EF. Try something like this (making some assumptions on your data/object model):

db.Categories
  .Where(x=> x.ID == category.ID)
  .Select(x=> new {
    Category = x,
    Section = db.Sections.FirstOrDefault(y => y.ID == x.SectionID),
    SubCategories = db.Categories.Where(y=> y.ParentCategoryID == x.ID)
  }).FirstOrDefault();

This will give you one object back (in one trip to the database) that has properties hydrated for the Category, Section, and SubCategories.