找不到适合实体类型的构造函数...EF8

Question

在 .net8 和 EF8 中我收到此错误：

找不到实体类型“DatabaseTableId”合适的构造函数。 以下构造函数具有无法绑定的参数 实体类型的属性： 无法在“DatabaseTableId(long value, bool isInternalError)”中绑定“value”、“isInternalError” 无法绑定“DatabaseTableId(DatabaseTableId value)”中的“value”请注意，只有映射的属性可以绑定到构造函数 参数。导航至相关实体，包括对 拥有的类型，无法绑定。

使用EF从数据库获取值时出现错误

在以下代码中：

public async Task<PetitionState> GetActualStateOfPetitionAsync(string PetitionId)
{
   try
   {
       ValueObjectExtensions.ThrowInternalArgumentNullExceptionIfNull(PetitionId);

       string? state = await _dbContext.WebServicePetitionState
           .Where(e => e.Id == PetitionId)
           .Select(e => e.State)
           .FirstOrDefaultAsync();

       return new PetitionState(state, true);
   }
   catch
   {
       throw;
   }
}

在 dbContext 类中：

public DbSet<WebServicePetitionStateEntity> WebServicePetitionState{ get; set; }

modelBuilder.Entity<WebServicePetitionStateEntity>()
   .ToTable("WEBSERVICE_PETITION_STATE", schema: "QUESTION")
   .HasKey(e => e.Id);

实体：

public class WebServicePetitionStateEntity
{
    [Key]
    [Column("ID")]
    public required string Id{ get; set; }
    [Column("RESPONSE_DATE")]
    public DateTime? ResponseDate{ get; set; }
    [Column("STATE")]
    public required string State{ get; set; }
}

“DatabaseTableId”是我创建的 ValueObject，但在此函数中未使用

namespace Domain.ValueObjects.Common;

/// <summary>
/// Represents a database table ID value object.
/// </summary>
public class DatabaseTableId : ValueObject<long>
{
    /// <summary>
    /// Gets the value of the database table ID.
    /// </summary>
    public override long Value { get; }

    /// <summary>
    /// Initializes a new instance of the <see cref="DatabaseTableId"/> class with the specified value.
    /// </summary>
    /// <param name="value">The value of the database table ID.</param>
    public DatabaseTableId(long value, bool isInternalError = false)
    {
        Value = value;
        ValidateAndThrow(isInternalError);
    }

    public DatabaseTableId() { }

    protected override void ValidateInternal()
    {
        if (Value <= 0)
        {
            throw new ArgumentException($"{nameof(DatabaseTableId)} cannot be less than or equal to 0.");
        }

        if (Value > long.MaxValue)
        {
            throw new ArgumentOutOfRangeException(nameof(DatabaseTableId), $"{nameof(DatabaseTableId)}: {Value} cannot have a length bigger than {long.MaxValue}.");
        }

        if (Value.ToString().Length > ValueObjectConstants.MaxIdLength)
        {
            throw new ArgumentOutOfRangeException(nameof(DatabaseTableId), $"{nameof(DatabaseTableId)}: {Value} cannot have more than {ValueObjectConstants.MaxIdLength} digits.");
        }
    }
}

和值对象

using Domain.Interfaces;

namespace Domain.Exceptions;


/// <summary>
/// Base class for all value objects that can be validated.
/// </summary>
/// <typeparam name="TValue">The type of the value of the value object.</typeparam>
public abstract class ValueObject<TValue>
{
    public abstract TValue Value { get; }

    /// <summary>
    /// Validates the value object and throws an exception if there are any validation errors, if isInternalException is true, throws a "InternalValidationExcepction" exception
    /// </summary>
    public void ValidateAndThrow(bool isInternalException = false)
    {
        try
        {
            ValidateInternal();
        }
        catch (Exception ex)
        {
            if (isInternalException)
            {
                throw new InternalValidationException(ex.Message);
            }
            else
            {
                throw;
            }
        }
    }

    /// <summary>
    /// Equality operator for value objects.
    /// </summary>
    /// <param name="left">The left value object.</param>
    /// <param name="right">The right value object.</param>
    /// <returns>True if the value objects are equal, false otherwise.</returns>
    public static bool operator ==(ValueObject<TValue>? left, ValueObject<TValue>? right)
    {
        if (ReferenceEquals(left, right))
        {
            return true;
        }

        if (left is null || right is null)
        {
            return false;
        }

        if (left.Value is null || right.Value is null)
        {
            return false;
        }

        return left.Value.Equals(right.Value);
    }

    /// <summary>
    /// Inequality operator for value objects.
    /// </summary>
    /// <param name="left">The left value object.</param>
    /// <param name="right">The right value object.</param>
    /// <returns>True if the value objects are not equal, false otherwise.</returns>
    public static bool operator !=(ValueObject<TValue>? left, ValueObject<TValue>? right)
    {
        return !(left == right);
    }

    /// <summary>
    /// Determines whether the current value object is equal to another object.
    /// </summary>
    /// <param name="obj">The object to compare with the current value object.</param>
    /// <returns>True if the current value object is equal to the other object, false otherwise.</returns>
    public override bool Equals(object? obj)
    {
        if (obj is ValueObject<TValue> other)
        {
            return Value != null && other.Value != null && Value.Equals(other.Value);
        }

        return false;
    }

    /// <summary>
    /// Serves as a hash function for a particular type.
    /// </summary>
    /// <returns>A hash code for the current value object.</returns>
    public override int GetHashCode() => Value?.GetHashCode() ?? 0;

    /// <summary>
    /// Returns a string that represents the current value object.
    /// </summary>
    /// <returns>A string that represents the current value object.</returns>
    public override string ToString() => Value?.ToString() ?? "";

    /// <summary>
    /// Validates the value object and returns a list of validation errors.
    /// </summary>
    /// <returns>A list of validation errors.</returns>
    protected abstract void ValidateInternal();
}

Answer 1

我解决了错误，在 DatabaseTableId 值对象中添加：

public DatabaseTableId() { }

。

此后此值对象不再出现此错误，但其他值对象出现此错误，修复后，它可以正常工作。

找不到实体类型字符串合适的构造函数