Question

有没有办法可以为Required，MaxLength和HasColumn组合多个属性，还是需要为每个属性创建一个属性？

我希望能够包含多个要求的字段，并且如果它们不是为实体中的每个字段创建一个新字段，那么就可以包含相同的MaxLength，就像我现在在下面做的那样。

public class DataEntryContext : DbContext
{
    public DataEntryContext(DbContextOptions<DataEntryContext> options)
        :base (options)
    { }

    public DbSet<Employee> Employees { get; set; }
    public DbSet<Department> Departments { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Employee>()
            .HasKey(e => e.EmpId);

        modelBuilder.Entity<Employee>()
            .Property(e => e.EmpFirstName)
            .HasColumnType("varchar(50)")
            .HasMaxLength(50)
            .IsRequired();

        modelBuilder.Entity<Employee>()
            .Property(e => e.EmpLastName)
            .HasColumnType("varchar(50)")
            .HasMaxLength(50)
            .IsRequired();

        modelBuilder.Entity<Employee>()
            .Property(e => e.EmpPhoneNumber)
            .HasColumnType("varchar(10)")
            .HasMaxLength(10)
            .IsRequired();

        modelBuilder.Entity<Employee>()
            .Property(e => e.EmpStartDate)
            .HasColumnType("datetime")
            .IsRequired();


        modelBuilder.Entity<Department>()
            .HasKey(d => d.DeptId);

        modelBuilder.Entity<Department>()
            .Property(d => d.DeptName)
            .HasColumnType("varchar(50)")
            .HasMaxLength(50)
            .IsRequired();

    }
}

Answer 1

当然可以，你只需要自己编写代码。例如，我写了一个EntityTypeConfigurationExtensions，它允许您在一次调用中配置具有多个属性的实体，而不是多次调用。我不明白为什么你不能修改我的代码以使用params，然后你可以传递多个属性：

（你必须先使用propertyConfiguration，然后是propertyExpression）

public static class EntityTypeConfigurationExtensions
{
    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, byte[]>> propertyExpression,
        Func<BinaryPropertyConfiguration, BinaryPropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, Guid>> propertyExpression,
        Func<PrimitivePropertyConfiguration, PrimitivePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, Guid?>> propertyExpression,
        Func<PrimitivePropertyConfiguration, PrimitivePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, TimeSpan?>> propertyExpression,
        Func<DateTimePropertyConfiguration, DateTimePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, TimeSpan>> propertyExpression,
        Func<DateTimePropertyConfiguration, DateTimePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, DateTimeOffset?>> propertyExpression,
        Func<DateTimePropertyConfiguration, DateTimePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, DateTimeOffset>> propertyExpression,
        Func<DateTimePropertyConfiguration, DateTimePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, DateTime?>> propertyExpression,
        Func<DateTimePropertyConfiguration, DateTimePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, DateTime>> propertyExpression,
        Func<DateTimePropertyConfiguration, DateTimePropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, decimal?>> propertyExpression,
        Func<DecimalPropertyConfiguration, DecimalPropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, decimal>> propertyExpression,
        Func<DecimalPropertyConfiguration, DecimalPropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }

    public static EntityTypeConfiguration<TEntityType> Property<TEntityType>(
        this EntityTypeConfiguration<TEntityType> instance,
        Expression<Func<TEntityType, string>> propertyExpression,
        Func<StringPropertyConfiguration, StringPropertyConfiguration> propertyConfiguration)
        where TEntityType : class
    {
        propertyConfiguration(instance.Property(propertyExpression));

        return instance;
    }
}

现在这个：

modelBuilder.Entity<Employee>()
  .HasKey(e => e.EmpId);

modelBuilder.Entity<Employee>()
  .Property(e => e.EmpFirstName)
  .HasColumnType("varchar(50)")
  .HasMaxLength(50)
  .IsRequired();

modelBuilder.Entity<Employee>()
  .Property(e => e.EmpLastName)
  .HasColumnType("varchar(50)")
  .HasMaxLength(50)
  .IsRequired();

modelBuilder.Entity<Employee>()
  .Property(e => e.EmpStartDate)
  .HasColumnType("datetime")
  .IsRequired();

现在：

modelBuilder.Entity<Employee>()
  .HasKey(e => e.EmpId)
  .Property(e => e.EmpFirstName,
    p => p.HasColumnType("varchar(50)")
     .HasMaxLength(50)
     .IsRequired())
  .Property(e => e.EmpLastName,
    p => p.HasColumnType("varchar(50)")
      .HasMaxLength(50)
      .IsRequired())
  .Property(e => e.EmpStartDate,
    p => p.HasColumnType("datetime")
      .IsRequired());

因此，修改我的代码以使用params并更新填充以循环遍历params：

modelBuilder.Entity<Employee>()
  .HasKey(e => e.EmpId)
  .Property(p => p.HasColumnType("varchar(50)")
    .HasMaxLength(50)
    .IsRequired(),
    e => e.EmpFirstName,
    e => e.EmpLastName);
  .Property(p => p.HasColumnType("datetime")
    .IsRequired(),
    e => e.EmpStartDate,);

Answer 2

目前还不可能。你必须为每个属性写那个。在max，您可以强制实体框架将.Net数据类型映射到特定的MS SQL数据类型，如here所示。

将modelBuilder配置为一次组合多个属性配置

2 个答案: