EF 迁移种子 - 无法创建“Application.Model.TranslationItem”类型的常量值

Posted 2023-02-26

【中文标题】EF 迁移种子 - 无法创建“Application.Model.TranslationItem”类型的常量值

【英文标题】：EF migration seed - Unable to create a constant value of type 'Application.Model.TranslationItem'

【发布时间】：2013-01-15 11:04:13

【问题描述】：

TranslationItem 模型：

[DataContract]
public class TranslationItem : CloneableBaseEntity<TranslationItem>, IValidatableObject


    public int TranslationId  get; set; 
    public Translation Translation  get; set; 

    public int Lcid  get; set;         

    private string _text;
    public string Text
    
        get  return _text; 
        set
        
            _text = value;
            RaisePropertyChanged("Text");
        
    

    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
    
        var t = validationContext.ObjectInstance as TranslationItem;   
        return t.Translation.Validate(validationContext);               
    

翻译模型：

[DataContract]
public class Translation : CloneableBaseEntity<Translation>, IValidatableObject

    private static int _englishLcid = 9;

    private  ObservableCollection<TranslationItem> _translations;
    [DataMember]
    public virtual ObservableCollection<TranslationItem> Translations
     
        get
            return _translations;
        
        set
        
            _translations = value;
            foreach (TranslationItem ti in _translations)
            
                ti.PropertyChanged += ti_PropertyChanged;
            
        
    

    ...
    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 

        Translation t;
        if(validationContext.ObjectInstance.GetType()== typeof(Translation))
            t = validationContext.ObjectInstance as Translation;
        else
            t =( validationContext.ObjectInstance as TranslationItem).Translation;

        if (!t.EnglishNotRequried)
        
            if (!t.TranslationDict.ContainsKey(_englishLcid) || String.IsNullOrEmpty(t.TranslationDict[_englishLcid].Text))
            
                yield return new ValidationResult("EnglishTranslationMissing");
            
        
    
 

我的迁移配置类中的 Seed 方法

protected override void Seed(DbContext context)

    int deLcid = new CultureInfo("en").LCID;
    int enLcid = new CultureInfo("en").LCID;


    TranslationItem enStd = context.TranslationItems.FirstOrDefault(ti => ti.Text == "Standard" && ti.Lcid == enLcid)
                            ?? new TranslationItem  Text = "Standard", Lcid = enLcid ;

    TranslationItem deStd = context.TranslationItems.FirstOrDefault(ti => ti.Text == "Standard" && ti.Lcid == deLcid)
                            ?? new TranslationItem  Text = "Standard", Lcid = deLcid ;

    context.Translations.AddOrUpdate(
        t => t.Translations,
        new Translation
            
                Translations = new ObservableCollection<TranslationItem>
                    
                        enStd,
                        deStd
                    
            );

    context.SaveChanges();

    context.EventTypes.AddOrUpdate(
        et => et.Name,
        new EventType
        
            Name = context.Translations.FirstOrDefault(t => t.Translations.Any(x => x.Lcid == enLcid && x.Text == "Standard") &&
                                                            t.Translations.Any(x => x.Lcid == deLcid && x.Text == "Standard") )
        );             

当我想更新数据库时出现以下错误

Unable to create a constant value of type 'PQS.Model.TranslationItem'. Only primitive types or enumeration types are supported in this context.

我不太确定如何解决这个问题。 我已经尝试先插入我的 TranslationItems，但是当我这样做时，验证失败，因为我猜需要翻译的 FK。

请帮忙！！

【参考方案1】：

我自己用一个小技巧修复了它（不完全是我喜欢的解决方案，但它现在可以工作）

我的问题：似乎AddOrUpdate(...) 我只能比较原始类型或枚举类型。

所以我添加了一个名为 SeedId 的附加 ID 来识别我的实体。

所以我在种子方法中的代码现在非常简单：

foreach (EventType eventtype in PqsDbContext.getStdEventTypes())

    context.EventTypes.AddOrUpdate(et => et.SeedId, eventtype);