请求特定数据将返回所有关联的实体，而不使用Include()

Question

我正在创建一个简单的web API(MVC(，目前我正在使用实体框架代码优先方法。我有以下实体：

作者、课程、机构

我建立了一种关系，一个作者可以拥有N个课程和N个机构。我正在API上编写以下方法：

public class PlutoController : ApiController
{
private readonly PlutoDbContext _context;
public PlutoController()
{
_context = new PlutoDbContext();
}
[HttpGet]
public IHttpActionResult GetAuthors()
{
var authors = _context.Authors
.Where(a => a.AuthorID == 1).ToList();
return Ok(authors);
}
}

然而，对api的调用会返回作者及其相关课程和机构。

[
{
"Courses": [
{
"CourseSections": [],
"Tags": [],
"CourseID": 1,
"AuthorID": 1,
"Title": "C# Advanced",
"Description": "C# Advanced Description",
"Price": 69,
"LevelString": "Advanced",
"Level": 3
},
{
"CourseSections": [],
"Tags": [],
"CourseID": 2,
"AuthorID": 1,
"Title": "C# Intermediate",
"Description": "C# Intermediate Description",
"Price": 49,
"LevelString": "Intermediate",
"Level": 2
},
{
"CourseSections": [],
"Tags": [],
"CourseID": 3,
"AuthorID": 1,
"Title": "Clean Code",
"Description": "Clean Code Description",
"Price": 99,
"LevelString": "Intermediate",
"Level": 2
}
],
"Institution": [
{
"InstitutionId": 1,
"AuthorId": 1,
"InstitutionName": "University of Windsor"
},
{
"InstitutionId": 2,
"AuthorId": 1,
"InstitutionName": "Boston University"
},
{
"InstitutionId": 4,
"AuthorId": 1,
"InstitutionName": "Arizona State University"
}
],
"AuthorID": 1,
"Name": "Bill Gates"
}]

在这一点上，我可以看到我们正在进行一些急切的加载，这不是我想要的。如何只获取作者的详细信息？

以下是我生成的模型：作者

namespace PlutoAPI.Models
{
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.Spatial;
public partial class Authors
{
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
public Authors()
{
Institution = new HashSet<Institution>();
Courses = new HashSet<Courses>();
}
[Key]
public int AuthorID { get; set; }
[Required]
[StringLength(255)]
public string Name { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<Institution> Institution { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<Courses> Courses { get; set; }
}
}

课程：

namespace PlutoAPI.Models
{
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.Spatial;
public partial class Courses
{
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
public Courses()
{
CourseSections = new HashSet<CourseSections>();
Tags = new HashSet<Tags>();
}
[Key]
public int CourseID { get; set; }
public int AuthorID { get; set; }
[Required]
[StringLength(255)]
public string Title { get; set; }
[Required]
[StringLength(8000)]
public string Description { get; set; }
public short Price { get; set; }
[Required]
[StringLength(50)]
public string LevelString { get; set; }
public byte Level { get; set; }
public virtual Authors Authors { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<CourseSections> CourseSections { get; set; }
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
public virtual ICollection<Tags> Tags { get; set; }
}
}

机构

namespace PlutoAPI.Models
{
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity.Spatial;
[Table("Institution")]
public partial class Institution
{
public int InstitutionId { get; set; }
public int? AuthorId { get; set; }
[Required]
[StringLength(50)]
public string InstitutionName { get; set; }
public virtual Authors Authors { get; set; }
}
}

Answer 1

您遇到的问题是LazyLoading(不急于加载(。禁用它。

public partial class YourDBContext : DbContext
{
public YourDBContext(): base("name=YourDBContext")
{
this.Configuration.LazyLoadingEnabled = false;
}
}