Question

我正在尝试执行LINQ查询并多次使用Include()来提取相关信息。

如果我执行以下查询，它可以正常工作：

var usersQuizzes = this.Context.EntitySet<Quiz>()
                    .Include(x => x.Questions)
                    .Include(x => x.QuizVersion)
                    .Include(x => x.QuizPasswords)
                    .Include(x => x.QuizVersion.Questions)
                    .Take(20)
                    .ToList();

但如果我这样做，我会收到错误：

var usersQuizzes = this.Context.EntitySet<Quiz>()
                    .Include(x => x.Questions)
                    .Include(x => x.QuizVersion)
                    .Include(x => x.QuizPasswords)
                    .Include(x => x.QuizVersion.Questions)
                    .Include(x => x.QuizVersions) // Added this
                    .Take(20)
                    .ToList();

或者：

var usersQuizzes = this.Context.EntitySet<Quiz>()
                    .Include(x => x.Questions)
                    .Include(x => x.QuizVersion)
                    .Include(x => x.QuizPasswords)
                    .Include(x => x.QuizVersion.Questions)
                    .Include(x => x.ResultDescriptions) // Added this instead
                    .Take(20)
                    .ToList();

或者：

 var usersQuizzes = this.Context.EntitySet<Quiz>()
                        .Include(x => x.QuizVersions)
                        .Include(x => x.ResultDescriptions)
                        .Include(x => x.QuizPasswords)
                        .Take(20)
                        .ToList();

但如果我删除QuizPasswords，则可行：

 var usersQuizzes = this.Context.EntitySet<Quiz>()
                        .Include(x => x.QuizVersions)
                        .Include(x => x.ResultDescriptions)
                        .Take(20)
                        .ToList();

错误消息

mscorlib.dll中发生了'System.FormatException'类型的异常   但未在用户代码中处理

附加信息：字符串未被识别为有效的布尔值。

Quiz.cs

public partial class Quiz
    {
        public Quiz()
        {
            this.TakerAnswers = new List<TakerAnswer>();
            this.FeaturedQuizzes = new List<FeaturedQuiz>();
            this.PersonalityOutcomes = new List<PersonalityOutcome>();
            this.PossibleAnswers = new List<PossibleAnswer>();
            this.Questions = new List<Question>();
            this.QuizLinks = new List<QuizLink>();
            this.QuizPasswords = new List<QuizPassword>();
            this.QuizSubmissions = new List<QuizSubmission>();
            this.QuizVersions = new List<QuizVersion>();
            this.ResultDescriptions = new List<ResultDescription>();
            this.Takers = new List<Taker>();
            this.PersonalityResultImages = new List<PersonalityResultImage>();
            this.PersonalityShareImages = new List<PersonalityShareImage>();
        }

        public int Id { get; set; }
        public int UserId { get; set; }
        public Nullable<int> QuizVersionId { get; set; }
        public string IpAddress { get; set; }

        [DefaultValue(false)]
        public bool IsPublic { get; set; }

        [DefaultValue(QuizType.Scored)]
        public QuizType QuizType { get; set; }

        public int CreatedTime { get; set; }
        public Nullable<int> BackgroundId { get; set; }

        [Index(IsUnique = true)]
        public string UrlId { get; set; }

        [DefaultValue(false)]
        public bool PasswordsDisabled { get; set; }

        [DefaultValue(false)]
        public bool SharedFacebook { get; set; }

        [DefaultValue(false)]
        public bool SharedTwitter { get; set; }

        [DefaultValue(false)]
        public bool Deleted { get; set; }

        [DefaultValue(false)]
        public bool ShowCorrections { get; set; }

        [DefaultValue(true)]
        public bool ShowBreakdown { get; set; }
        public string Thumbnail { get; set; }
        public string ShareImage { get; set; }
        public Nullable<int> QuizLinkId { get; set; }

        [DefaultValue(false)]
        public bool ForceShareImage { get; set; }

        [DefaultValue(0)]
        public int ShareCount { get; set; }

        [DefaultValue(BackgroundAlign.Top)]
        public BackgroundAlign BackgroundAlign { get; set; }

        public string BackgroundColour { get; set; }
        public string TextColour { get; set; }
        public virtual ICollection<TakerAnswer> TakerAnswers { get; set; }
        public virtual ICollection<FeaturedQuiz> FeaturedQuizzes { get; set; }
        public virtual ICollection<PersonalityOutcome> PersonalityOutcomes { get; set; }
        public virtual ICollection<PossibleAnswer> PossibleAnswers { get; set; }
        public virtual ICollection<Question> Questions { get; set; }
        public virtual ICollection<QuizLink> QuizLinks { get; set; }
        public virtual ICollection<QuizPassword> QuizPasswords { get; set; }
        public virtual ICollection<QuizSubmission> QuizSubmissions { get; set; }
        public virtual ICollection<QuizVersion> QuizVersions { get; set; }
        public virtual QuizBackground QuizBackground { get; set; }
        public virtual QuizLink QuizLink { get; set; }
        public virtual QuizVersion QuizVersion { get; set; }
        public virtual User User { get; set; }
        public virtual ICollection<ResultDescription> ResultDescriptions { get; set; }
        public virtual ICollection<Taker> Takers { get; set; }
        public virtual ICollection<PersonalityResultImage> PersonalityResultImages { get; set; }
        public virtual ICollection<PersonalityShareImage> PersonalityShareImages { get; set; }
    }

QuizVersion.cs

public partial class QuizVersion
    {
        public QuizVersion()
        {
            this.TakerAnswers = new List<TakerAnswer>();
            this.FeaturedQuizzes = new List<FeaturedQuiz>();
            this.PersonalityOutcomes = new List<PersonalityOutcome>();
            this.PossibleAnswers = new List<PossibleAnswer>();
            this.Questions = new List<Question>();
            this.QuizSubmissions = new List<QuizSubmission>();
            this.Takers = new List<Taker>();
        }

        public int Id { get; set; }
        public int QuizId { get; set; }
        public string QuizName { get; set; }
        public string QuizIntro { get; set; }
        public string IpAddress { get; set; }
        public bool Public { get; set; }
        public int CreatedTime { get; set; }
        public virtual ICollection<TakerAnswer> TakerAnswers { get; set; }
        public virtual ICollection<FeaturedQuiz> FeaturedQuizzes { get; set; }
        public virtual ICollection<PersonalityOutcome> PersonalityOutcomes { get; set; }
        public virtual ICollection<PossibleAnswer> PossibleAnswers { get; set; }
        public virtual ICollection<Question> Questions { get; set; }
        public virtual Quiz Quiz { get; set; }
        public virtual ICollection<QuizSubmission> QuizSubmissions { get; set; }
        public virtual ICollection<Taker> Takers { get; set; }
    }

ResultDescription.cs

public partial class ResultDescription
{
    public int Id { get; set; }
    public int QuizId { get; set; }
    public Nullable<int> Percentage { get; set; }
    public string Description { get; set; }

    [DefaultValue(false)]
    public bool Deleted { get; set; }

    public virtual Quiz Quiz { get; set; }
}

我认为我的数据库中可能存在一些狡猾的值，但我检查了POCO类中的所有bool类型值，它们似乎都是tinyint(1)类型并设置为1或0且无空值。

可能导致此错误的原因是什么？

Answer 1

我遇到了同样的问题并在第一个错误示例中使用了此解决方法：

var usersQuizzes = this.Context.EntitySet<Quiz>()
                .Include(x => x.Questions)
                .Include(x => x.QuizVersion)
                .Include(x => x.QuizPasswords)
                .Include(x => x.QuizVersion.Questions);

this.Context.Entry(userQuizes).Collection("QuizVersions").Load();

userQuizes.Take(20).ToList();

Answer 2

我已经设法通过切换包含顺序并将错误的包含放在首位（在您的情况下是x.QuizPasswords）来使我的代码工作

Answer 3

我找到了一种强制将属性设置为“位”默认值“假”的解决方案。我在Mysql中更改了数据类型。 Tinyint->位。

[Column("Active", TypeName = "bit")]
[DefaultValue(false)]
public bool Active { get; set;

链接参考：

Entity Framework MySQL tinyint(1) System.Boolean.Parse FormatException

在MySQL Linq查询EF6中使用多个Include（）方法时格式异常

错误消息

3 个答案: