将AutoMapper与DataTable一起使用缺少的列 [英] Using AutoMapper with DataTable with missing columns

问题描述

我正在使用AutoMapper将数据表映射到列表.

I'm using AutoMapper to map a datatable to a List.

在我的情况下，数据表的列可能会根据外部变量而变化.

In my scenario, the columns for the datatable may change depending on an outside variable.

我可以成功地将数据表映射到具有以下内容的对象:

I can successfully map the datatable to the object w/ the following:

AutoMapper.Mapper.CreateMap<IDataReader, Person>();

DataTableReader dtr = myDataTable.CreateDataReader();
List<Person> people = new List<Person>();

people = AutoMapper.Mapper.Map<List<Person>>(dtr);

一切正常.但是我需要将某些属性转换为表中可能存在或不存在的列上的整数.

This all works fine. But there are some properties that I need to convert to integer on columns that may or may not exist in the table.

示例:

AutoMapper.Mapper.CreateMap<IDataReader, Person>()
    .FromMember(dest => dest.NumberOfOrders, opt => opt.MapFrom(src => Convert.ToInt32(src["HowManyOrders"])));

表中可能并不总是存在"HowManyOrders"列，那么我该如何检查该列是否存在，然后转换该值呢?

The column "HowManyOrders" might not always exist in the table, so how do I go about checking if the column exists and then converting the value if it does?

推荐答案

您应该可以使用AfterMap:

You should be able to use AfterMap:

    Mapper.CreateMap<IDataReader, Person>()
          .AfterMap((source, dest) =>
                       {
                         if (ColumnExists(source, "HowManyOrders"))
                         {
                             dest.NumberOfOrders = 
                                     Convert.ToInt32(source["HowManyOrders"]);
                         }
                       });
    ... 

    public bool ColumnExists(IDataReader reader, string columnName)
    {
        for (int i = 0; i < reader.FieldCount; i++)
        {
            if (reader.GetName(i) == columnName)
            {
                return true;
            }
        }

        return false;
    }

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