将DataTable转换为List <T>

Question

我有一个疑问,有时我将此转换DataTable为List<T>:

  List<EDog> lstDogs = (from drRow in dsDogs.Tables[0].AsEnumerable()
                        select new EDog()
                        {
                            intIdDog = drRow.Field<int>("IdDog"),
                            intIdOwner = drRow.Field<int?>("IdOwner"),
                            intAge = drRow.Field<int>("Age"),
                            strName = drRow.Field<string>("Name")
                       }).ToList();

这工作正常,但现在我正在考虑将它做为通用,以便任何类型的DataSet都可以转换为强类型列表.

我怎么能把它变成通用的呢？也许围绕这部分并创建对象的代表？

new EDog()
{
    intIdDog = drRow.Field<int>("IdDog"),
    intIdOwner = drRow.Field<int?>("IdOwner"),
    intAge = drRow.Field<int>("Age"),
    strName = drRow.Field<string>("Name")
}

我试了但是得到了一个错误:

select (lambda) expected....

有什么建议吗？

我之所以需要这个,是因为结果的每个DataRow都需要转换为Entity以便更好地操作.

Answer 1

好的,让我们玩得开心:

public static class DataTableExtensions
{
    public static List<T> ToGenericList<T>(this DataTable datatable, Func<DataRow, T> converter)
    {
        return (from row in datatable.AsEnumerable()
                select converter(row)).ToList();
    }
}

class EDog
{
    private int intIdDog;
    private int intIdOwner;
    private int intAge;
    private string strName;

    ...

    public static EDog Converter(DataRow row)
    {
        return new EDog
                        {
                            intIdDog = (int)row["IdDog"],
                            intIdOwner = (int)row["IdOwner"],
                            intAge = (int)row["Age"],
                            strName = row["Name"] as string
                        };
    }
}

用法:

List<EDog> dogs = dsDogs.Tables[0].ToGenericList<EDog>(EDog.Converter);

但是没有足够的乐趣,对吧？那这个呢:

class DataRowKeyAttribute : Attribute
{
    private readonly string _Key;

    public string Key
    {
        get { return _Key; }
    }

    public DataRowKeyAttribute(string key)
    {
        _Key = key;
    }
}


static class DataTableExtensions
{
    public static List<T> ToGenericList<T>(this DataTable datatable) where T : new()
    {
        return (from row in datatable.AsEnumerable()
                select Convert<T>(row)).ToList();
    }

    private static T Convert<T>(DataRow row) where T : new()
    {
        var result = new T();

        var type = result.GetType();

        foreach (var fieldInfo in type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance))
        {
            var dataRowKeyAttribute = fieldInfo.GetCustomAttributes(typeof (DataRowKeyAttribute), true).FirstOrDefault() as DataRowKeyAttribute;
            if (dataRowKeyAttribute != null)
            {
                fieldInfo.SetValue(result, row[dataRowKeyAttribute.Key]);
            }
        } 

        return result;
    }
}

class EDog
{
    [DataRowKey("IdDog")]
    private int intIdDog;
    [DataRowKey("IdOwner")]
    private int intIdOwner;
    [DataRowKey("Age")]
    private int intAge;
    [DataRowKey("Name")]
    private string strName;

    ... 
}

用法:

List<EDog> dogs = dsDogs.Tables[0].ToGenericList<EDog>();

如果您希望获得真正的乐趣,请添加错误处理,请考虑缓存反射数据以提高性能并将字段更改为属性.

Answer 2

这是你想要的东西吗？

public static List<T> ConvertDS<T>(DataSet ds, Converter<DataRow, T> converter)
{
    return
        (from row in ds.Tables[0].AsEnumerable()
         select converter(row)).ToList();
}