Question

这是我的情况，我必须创建一个将值插入MySQL数据库的通用函数。到目前为止，我有以下方法。当另一个类中没有复合类时，此代码可以正常工作。如果我们在实体中有导航属性然后这个代码中断了，我就被困在这里。

（ORM - 我们不能使用它，因为它的客户要求）

public string create(object entity){
    var sql = new OdbcCommand();
        var d = new StringDictionary();
        var dd = new StringDictionary();
        try
        {
            var objectType = entity.GetType();
            var properties = objectType.GetProperties();
            var tableName = objectType.GetCustomAttributes(false).Select(x => (x as TableAttribute).Name).FirstOrDefault();
            foreach (var prop in properties)
            {
                if (prop.DeclaringType != typeof (BasicRequest)) // BasicRequest is base class
                {
                    if (
                        prop.GetCustomAttributes(false).Where(y=>y is ColumnAttribute).Select(x => (x as ColumnAttribute)).FirstOrDefault().IsPrimaryKey)
                    {
                        continue;
                    }
                    if (prop.PropertyType.IsGenericType) // here comes the problem
                    {
                        // the problem is if a class has List of its child 
                          objects then how to insert them since here parent 
                          is not yet inserted.
                    }
                    if (prop.GetCustomAttributes(false).Where(y => y is ColumnAttribute).Select(x => (x as ColumnAttribute)).FirstOrDefault().IsParent)
                    {
                         // same problem here also but this time this object is
                         parent object of the entity
                        /*parentObject = prop.GetValue(entity, null);
                        CreateNew(parentObject);
                        */

                        continue;
                    }
                    d[prop.GetCustomAttributes(false).Where(y => y is ColumnAttribute).Select(x => (x as ColumnAttribute).Name).FirstOrDefault()] = DBUtil.FixSQLString(Convert.ToString(prop.GetValue(entity, null)));
                }
                else
                {
                    continue;
                }
            }
            Connection coxn = ConnectionPool.GetInstance().GetCoxn(Constants.MyName,ConnectionPool.WriteServer,"db_name");
            sql.Connection = coxn.odbcConnection;
            sql.CommandType = CommandType.Text;
            sql.CommandText = DBUtil.CreateInsert(tableName, d);
            int affected = sql.ExecuteNonQuery();

            if (affected != 1)
            {
                ErrorMessage = "Insert Failed Unexpectedly";
                return "0";
            }
            return "1";

        }
        catch (Exception ex)
        {
            ErrorMessage = ex.Message;
            return "0";
        }
}

让我们拿一个实体（这种设计不在我手中，这个类已经存在了我不能改变这个实体）

[Table(Name="person")]
public class Person
{
    [Column(Name="id",IsPrimaryKey=true)] // Column is my custom attribute
    public int Id{get;set;}
    [Column(Name="name",IsPrimaryKey=true)]
    public string Name{get;set;}
   // this is where i'm not able get it how do i insert
   // child class with the function i wrote above 
    [Column(IsChild=true)]
    public List<Contact> contact{get;set;} // Navigation property
    //Same problem with this property also 
    // how do i do insert for parent
    [Column(IsParent=true)]
    public User user{get;set;}

}

// i'll call that insert method as
Common c = new Common();
c.Create(Person p); // p will be passed as argument from controller

Answer 1

请允许我建议使用micro-orm，而不是手写所有这些功能。

我建议Dapper或PetaPoco（您可以将其作为单个文件添加到您的应用中）。

Answer 2

看起来您正在尝试创建自己的ORM实现。这将非常复杂，绝对不值得为客户项目付出努力。

您可以使用代码生成工具从数据库结构生成数据访问层。例如CodeSmith http://www.codesmithtools.com/。

使用反射C＃的常见CRUD函数

2 个答案: