entity-framework - Entity Framework 渴望加载单个实体

Question

我的 WebApi Controller 的精简版是这样的:

[HttpGet, Route("")]
public async Task<IHttpActionResult> Search(bool includeEntities)
{
    IQueryable<VersionTopic> results = DbContext.VersionTopics;
    if (includeEntities)
    {
        results = results.Include(o => o.CreatedBy);
        results = results.Include(o => o.LastSavedBy);
        results = results.Include(o => o.Topic.LastSavedBy);
        results = results.Include(o => o.Topic.CreatedBy);
        results = results.Include(o => o.Topic.PACKType.LastSavedBy);
        // etc...
    }

    results = results.OrderBy(o => o.SortOrder);

    return Ok(result.ToList());
}

出于某种原因，LastSavedBy 实体始终被填充，即使 includeEntities 参数为 false。

为什么它会急于只加载一个实体而不加载其他实体(按要求)？

截图如下:

我的模型是这样定义的:

public class VersionTopic
{
    [Key]
    [Required]
    public Guid VersionTopicId { get; set; }

    [Required]
    [Index("IX_VersionTopic_VersionId_TopicId", IsUnique = true, Order = 0)]
    public Guid VersionId { get; set; }

    [Required]
    [Index("IX_VersionTopic_VersionId_TopicId", IsUnique = true, Order = 1)]
    public Guid TopicId { get; set; }

    [Required(AllowEmptyStrings = true)]
    [MaxLength(250)]
    public string Name { get; set; }

    public string KeyMessage { get; set; }

    [Required]
    public int SortOrder { get; set; }

    [Required]
    public Guid CreatedById { get; set; }

    [Required]
    public DateTime CreatedDate { get; set; }

    [Required]
    public Guid LastSavedById { get; set; }

    [Required]
    public DateTime LastSavedDate { get; set; }

    public virtual ICollection<VersionRecommendation> VersionRecommendations { get; set; } = new List<VersionRecommendation>();

    [ForeignKey("CreatedById")]
    public virtual ApplicationUser CreatedBy { get; set; }

    [ForeignKey("LastSavedById")]
    public virtual ApplicationUser LastSavedBy { get; set; }

    [ForeignKey("TopicId")]
    public virtual Topic Topic { get; set; }

    [ForeignKey("VersionId")]
    public virtual Version Version { get; set; }

    public VersionTopic()
    {
        VersionTopicId = Guid.NewGuid();
    }
}

Answer 1

下面的Tip中基本上解释了Loading Related Data - Eager Loading EF Core 文档的一部分，但同样适用于 EF6 及以下版本:

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.

不幸的是，这种行为是不可控的，所以避免它的唯一选择是使用全新的 DbContext(或手动清理不需要的导航属性，但这很烦人且容易忘记).