我有几个方法返回不同的泛型列表。

在。net中存在任何类静态方法或将任何列表转换为数据表?我唯一能想到的是使用反射来做到这一点。

如果我有这个:

List<Whatever> whatever = new List<Whatever>();

(这下代码当然不工作,但我想有这样的可能性:

DataTable dt = (DataTable) whatever;

当前回答

这是一个简单的混合溶液。 它适用于Nullable类型。

public static DataTable ToDataTable<T>(this IList<T> list)
{
  PropertyDescriptorCollection props = TypeDescriptor.GetProperties(typeof(T));
  DataTable table = new DataTable();
  for (int i = 0; i < props.Count; i++)
  {
    PropertyDescriptor prop = props[i];
    table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
  }
  object[] values = new object[props.Count];
  foreach (T item in list)
  {
    for (int i = 0; i < values.Length; i++)
      values[i] = props[i].GetValue(item) ?? DBNull.Value;
    table.Rows.Add(values);
  }
  return table;
}

其他回答

将通用列表转换为数据表

使用Newtonsoft.Json;

public DataTable GenericToDataTable(IList<T> list)
{
    var json = JsonConvert.SerializeObject(list);
    DataTable dt = (DataTable)JsonConvert.DeserializeObject(json, (typeof(DataTable)));
    return dt;
}

我自己编写了一个小型库来完成这个任务。它只在将对象类型转换为数据表时第一次使用反射。它发出一个方法,该方法将完成转换对象类型的所有工作。

它燃烧得很快。你可以在这里找到它:

ToDataTable()在MoreLinq上的GitHub 原:ModelShredder在GoogleCode,被合并到MoreLinq,从GoogleCode移动到GitHub

It's also possible through XmlSerialization.
The idea is - serialize to `XML` and then `readXml` method of `DataSet`.

I use this code (from an answer in SO, forgot where)

        public static string SerializeXml<T>(T value) where T : class
    {
        if (value == null)
        {
            return null;
        }

        XmlSerializer serializer = new XmlSerializer(typeof(T));

        XmlWriterSettings settings = new XmlWriterSettings();

        settings.Encoding = new UnicodeEncoding(false, false);
        settings.Indent = false;
        settings.OmitXmlDeclaration = false;
        // no BOM in a .NET string

        using (StringWriter textWriter = new StringWriter())
        {
            using (XmlWriter xmlWriter = XmlWriter.Create(textWriter, settings))
            {
               serializer.Serialize(xmlWriter, value);
            }
            return textWriter.ToString();
        }
    }

so then it's as simple as:

            string xmlString = Utility.SerializeXml(trans.InnerList);

        DataSet ds = new DataSet("New_DataSet");
        using (XmlReader reader = XmlReader.Create(new StringReader(xmlString)))
        { 
            ds.Locale = System.Threading.Thread.CurrentThread.CurrentCulture;
            ds.ReadXml(reader); 
        }

Not sure how it stands against all the other answers to this post, but it's also a possibility.

我意识到这里已经关门有一段时间了;然而,我有一个解决这个特定问题的解决方案,但需要稍微扭转:列和数据表需要预先定义/已经实例化。然后我只需将类型插入到数据表中。

下面是我所做的一个例子:

public static class Test
{
    public static void Main()
    {
        var dataTable = new System.Data.DataTable(Guid.NewGuid().ToString());

        var columnCode = new DataColumn("Code");
        var columnLength = new DataColumn("Length");
        var columnProduct = new DataColumn("Product");

        dataTable.Columns.AddRange(new DataColumn[]
            {
                columnCode,
                columnLength,
                columnProduct
            });

        var item = new List<SomeClass>();

        item.Select(data => new
        {
            data.Id,
            data.Name,
            data.SomeValue
        }).AddToDataTable(dataTable);
    }
}

static class Extensions
{
    public static void AddToDataTable<T>(this IEnumerable<T> enumerable, System.Data.DataTable table)
    {
        if (enumerable.FirstOrDefault() == null)
        {
            table.Rows.Add(new[] {string.Empty});
            return;
        }

        var properties = enumerable.FirstOrDefault().GetType().GetProperties();

        foreach (var item in enumerable)
        {
            var row = table.NewRow();
            foreach (var property in properties)
            {
                row[property.Name] = item.GetType().InvokeMember(property.Name, BindingFlags.GetProperty, null, item, null);
            }
            table.Rows.Add(row);
        }
    }
}

试试这个

public static DataTable ListToDataTable<T>(IList<T> lst)
{

    currentDT = CreateTable<T>();

    Type entType = typeof(T);

    PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
    foreach (T item in lst)
    {
        DataRow row = currentDT.NewRow();
        foreach (PropertyDescriptor prop in properties)
        {

            if (prop.PropertyType == typeof(Nullable<decimal>) || prop.PropertyType == typeof(Nullable<int>) || prop.PropertyType == typeof(Nullable<Int64>))
            {
                if (prop.GetValue(item) == null)
                    row[prop.Name] = 0;
                else
                    row[prop.Name] = prop.GetValue(item);
            }
            else
                row[prop.Name] = prop.GetValue(item);                    

        }
        currentDT.Rows.Add(row);
    }

    return currentDT;
}

public static DataTable CreateTable<T>()
{
    Type entType = typeof(T);
    DataTable tbl = new DataTable(DTName);
    PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
    foreach (PropertyDescriptor prop in properties)
    {
        if (prop.PropertyType == typeof(Nullable<decimal>))
             tbl.Columns.Add(prop.Name, typeof(decimal));
        else if (prop.PropertyType == typeof(Nullable<int>))
            tbl.Columns.Add(prop.Name, typeof(int));
        else if (prop.PropertyType == typeof(Nullable<Int64>))
            tbl.Columns.Add(prop.Name, typeof(Int64));
        else
             tbl.Columns.Add(prop.Name, prop.PropertyType);
    }
    return tbl;
}