使用复合键-实体框架核心更新记录

Question

我在使用EF Core 5和Net Core 5使用复合键更新记录时遇到问题。我能够使用组合键的两个部分(在我的情况下两个id)获得记录，但是当我将更改保存到数据库时，我得到以下错误:

数据库操作预计影响1行，但实际影响24行。自实体加载以来，数据可能已被修改或删除。有关理解和处理乐观并发异常的信息，请参阅http://go.microsoft.com/fwlink/?LinkId=527962。

在数据库中查看后，看起来像实体框架试图更新表中具有相同id(复合键的第一部分)的所有记录，而不是更新我得到的记录。

还有人看到这种行为吗?你知道该怎么解决这个问题或者我做错了什么吗?

下面是表设置的基本版本

Table1:

Id (PK)

表:

Id (PK),  
Table1Id (PK, FK)

失败的场景:

Table1:

Id  
--
1  
2  

表:

Id, Table1Id  
------------
1, 1  
2, 1  
1, 2  
2, 2  

如果我尝试更新Table2(1,1)中的第一个记录，EF将尝试更新它和第三个记录(1,2)并抛出上述错误。

代码:

// Getting record    
var record = await context.Table2s
.FirstOrDefaultAsync(e => e.Id == 1 && e.Table1Id == 1, cancellationToken);
// Saving
await context.SaveChangesAsync(cancellationToken);
// I have also tried specifying which record to update before saving
context.Table2s.Update(record);

配置表2:

builder.ToTable("Table2");
builder.HasKey(e => new { e.Id, e.Table1Id });
builder.HasOne(e => e.Table1)
.WithMany(m => m.Table2s)
.HasForeignKey(e => e.Table1Id)
.OnDelete(DeleteBehavior.Cascade);

Answer 1

它在我自己的项目中工作，我希望它会有用。

protected override void OnModelCreating(DbModelBuilder mb) {
mb.Entity<WebServisUser>().HasKey(x => new
{
x.Proje, /* Composite Keys */
x.KulAdi /* Composite Keys */
});
mb.Entity<WebServisUser>().Property(e => e.Proje).IsUnicode(false);
mb.Entity<WebServisUser>().Property(e => e.KulAdi).IsUnicode(false);
}

为了更好地理解，我添加了其他函数的链接。

public static class Helper
{
public static bool IsNull(this object value) => (value == null || Convert.IsDBNull(value) || Convert.GetTypeCode(value) == TypeCode.Empty);
public static bool IsNotNull(this object value) => !value.IsNull();
public static string ToPropertyName(this Expression value)
{
if (typeof(LambdaExpression).IsAssignableFrom(value.GetType())) { value = ((LambdaExpression)value).Body; }
if (value is MemberExpression e_mem) { return e_mem.Member.Name; }
else if (value is UnaryExpression e_una) { return ((MemberExpression)e_una.Operand).Member.Name; }
else { throw new InvalidCastException(String.Format("value type can be "{0}" or "{1}"", nameof(MemberExpression), nameof(UnaryExpression))); }
}
public static object ChangeType(object value, Type type)
{
var c = TryTypeIsNullable(type, out Type _outtype);
return (c && value.IsNull()) ? null : (_outtype.IsEnum ? Enum.ToObject(_outtype, value) : Convert.ChangeType(value, c ? Nullable.GetUnderlyingType(type) : type));
}
public static void SetPropertyValue<T>(this T value, string propertyname, object data) where T : class
{
var p = typeof(T).GetProperty(propertyname);
p.SetValue(value, data.IsNull() ? null : ChangeType(data, p.PropertyType));
}
public static bool TryTypeIsNullable(Type value, out Type outvalue)
{
var t = (value.IsGenericType && value.GetGenericTypeDefinition().Equals(typeof(Nullable<>)));
outvalue = (t ? value.GenericTypeArguments[0] : value); return t;
}
public static bool TryTypeIsAttribute<T, Y>(T value, out Y outvalue) where T : ICustomAttributeProvider where Y : Attribute
{
bool ret;
try
{
var v = value.GetType();
var y = typeof(Y);
if (typeof(Assembly).IsAssignableFrom(v) && Attribute.IsDefined((Assembly)((object)value), y)) { ret = true; }
else if (typeof(MemberInfo).IsAssignableFrom(v) && Attribute.IsDefined((MemberInfo)((object)value), y)) { ret = true; }
else if (typeof(Module).IsAssignableFrom(v) && Attribute.IsDefined((Module)((object)value), y)) { ret = true; }
else if (typeof(ParameterInfo).IsAssignableFrom(v) && Attribute.IsDefined((ParameterInfo)((object)value), y)) { ret = true; }
else { ret = false; }
outvalue = ret ? value.GetCustomAttributes(y, false).Cast<Y>().Take(1).FirstOrDefault() : default;
}
catch
{
outvalue = default;
ret = false;
}
return ret;
}
public static void SetCompositeKey<T, TKey>(this DbContext context, T entity, Expression<Func<T, TKey>> compositekey, TKey compositekeyvalue, Action<T> actionislem = null) where T : class, new()
{
var t = typeof(T);
var c = compositekey.ToPropertyName();
var ie_prop = typeof(T).GetProperties().Where(x => x.GetMethod.IsNotNull() && x.SetMethod.IsNotNull() && !x.GetMethod.IsVirtual && !x.SetMethod.IsVirtual && !Helper.TryTypeIsAttribute(x, out NotMappedAttribute _)).Select(x => new
{
name = x.Name,
iskey = x.Name == c,
iscompositekey = Helper.TryTypeIsAttribute(x, out KeyAttribute _outkeyvalue) && _outkeyvalue.IsNotNull() && Helper.TryTypeIsAttribute(x, out DatabaseGeneratedAttribute _outdatagenvalue) && _outdatagenvalue.DatabaseGeneratedOption == DatabaseGeneratedOption.None
});
if (ie_prop.Where(x => x.iscompositekey).Count() < 2) { throw new KeyNotFoundException("minimum of 2 composite keys exception message..."); }
else if (ie_prop.Any(x => x.iscompositekey && x.iskey))
{
var addentity = new T();
var e = context.Entry<T>(entity);
var dbset = context.Set<T>();
dbset.Attach(entity);
foreach (var item in ie_prop.Select(x => new
{
x.name,
x.iskey
})) { addentity.SetPropertyValue(item.name, item.iskey ? compositekeyvalue : e.Property(item.name).OriginalValue); }
dbset.Add(addentity); /* Insert record about new key value */
if (actionislem.IsNotNull()) { actionislem(addentity); } /* If there are other areas of connection, do the operations there with the action method. */
dbset.Remove(entity); /* delete old value */
}
else { throw new Exception("compositekey must be composite key exception message..."); }
}
}

和例子

using (var mdl = new mdlBayUniOrtak())
{
using (var c = new TransactionScope())
{
var beforeentity = mdl.WebServisUsers.Where(x => x.Proje == "loremipsum").Take(1).FirstOrDefault();
var e = new Action<WebServisUser>((WebServisUser afterentity) =>
{
/* Other actions if necessary. Other foreign key operations can be done here! */
});
mdl.SetCompositeKey(beforeentity, x => x.KulAdi, "galatasaray", e);
mdl.SaveChanges();
c.Complete();
}
}