c# - EF Fluent api poco 使用现有 Db 生成和映射

Question

我有 2 个表，如下所示，我对应该如何创建 poco 类以及如何映射它们感到困惑。

我已经创建了如下的 POCO 类。

public partial class ExpenseIncome
{
    public int ID { get; set; }
    public int? ExpIncTypeID { get; set; }
    public int AccountID { get; set; }
    public decimal? Amount { get; set; }
    public int? UserID { get; set; }
    public int? GroupID { get; set; }
    public DateTime? AddedDate { get; set; }
    public string Explanation { get; set; }
    public int? ParentItemID { get; set; }
    public decimal? Balance { get; set; }
    public bool? IsActive { get; set; }
    public DateTime? ActivationDate { get; set; }
    // this is  navigation property
    public virtual ExpenseIncomeType ExpenseIncomeType { get; set; }
}

其他 POCO 是:

public partial class ExpenseIncomeType
{
    public int ID { get; set; }
    public string TName { get; set; }
    public int? IsExpOrInc { get; set; }
    public int? ParentExpTypeID { get; set; }
    public decimal? ExpIncTypeDefaultAmount { get; set; }
    public string UserGroupUniqueValue { get; set; }
    public int? UserGroupID { get; set; }
    // this is  navigation property
    public virtual ExpenseIncome ExpenseIncome { get; set; }
}

所以，我对如何在 DbContext 的 ModelCreating(DbModelBuilder modelBuilder) 方法中映射这些类感到困惑？

Answer 1

如果您打算采用 Code First 方法，至少有两种方法可以做到这一点。

1. 在 DbContext 中，您必须像您所说的那样覆盖 ModelCreating，并为每个实体编写如下内容:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)       {         modelBuilder.Entity<ExpenseIncome>().HasKey(e => e.ID);        modelBuilder.Entity<ExpenseIncomeType>().HasKey(e => e.ID);      }

2. Create a mapping class derived from EntityTypeConfiguration and in the constructor of that class indicate related mappings.

    public class ExpenseIncomeMap: EntityTypeConfiguration<ExpenseIncome>    {     public RoleConfiguration()      {        HasKey(e => e.ID);        // etc.      }    }

And after this each mapping class should be added to context

protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new ExpenseIncomeMap());
        modelBuilder.Configurations.Add(new ExpenseIncomeTypeMap());
    }

DbContext 中的 Poco 模型应该与数据库结构完全匹配，在这种情况下，您不需要生成任何数据库迁移。