如何IEnumerable的<T>列表轉換爲數據表在C＃中

Question

我堅持以下問題：

我通常使用下面的功能自定義的數據傳輸到數據表，但在這種情況下，輸入數據是列表構成的一類。我只需要在DataTable中寫入每行每個列表的第一個元素。你能幫我調整這個功能來實現嗎？

public List<int> xID { get; set; } 
public List<string> xName { get; set; } 
public List<string> xType { get; set; } 
public List<string> xSource { get; set; } 
public List<int> xmdID { get; set; } 
public List<string> xMDName { get; set; } 
public List<string> xUser { get; set; } 

public static DataTable ListToDataTable<T>(IEnumerable<T> list) 
{ 
    Type type = typeof(T); 
    var properties = type.GetProperties(); 

    DataTable dataTable = new DataTable(); 
    foreach (PropertyInfo info in properties) 
    { 
     dataTable.Columns.Add(new DataColumn(info.Name, info.PropertyType)); 
    } 

    foreach (T entity in list) 
    { 
     object[] values = new object[properties.Length]; 
     for (int i = 0; i < properties.Length; i++) 
     { 
      values[i] = properties[i].GetValue(entity); 
     } 

     dataTable.Rows.Add(values); 
    } 

    return dataTable; 
} 

---

總部設在卡拉答案我想下面的代碼，但它不承認p-型類型（類型或命名空間名稱「的p-型」找不到（是否缺少using指令或程序集引用？））

var v = properties[i].GetValue(entity); 
Type pType = properties[i].PropertyType; 

if (pType.IsGenericType && pType.GetGenericTypeDefinition() == typeof(Nullable<>)) 
pType = Nullable.GetUnderlyingType(pType); 

       if (pType.IsEnum) 
        pType = Enum.GetUnderlyingType(pType); 

       if (v.GetType().GetGenericTypeDefinition() == typeof(List<>)) 
       { 
        values[i] = (v as List<pType>).First(); 
       } 

---

UPDATE

我想這是不是最好的解決方案，因爲它不accep牛逼任何列表類型，但它是我能做的最好的：

public static DataTable ListToDataTable<T>(IEnumerable<T> list) 
    { 
     Type type = typeof(T); 
     var properties = type.GetProperties(); 

     DataTable dataTable = new DataTable(); 
     foreach (PropertyInfo info in properties) 
     { 
      Type propertyType = info.PropertyType; 

      if (propertyType.IsGenericType | propertyType.GetGenericTypeDefinition() == typeof(Nullable<>) | propertyType.IsEnum) 
       propertyType = propertyType.GetGenericArguments()[0]; 

      dataTable.Columns.Add(new DataColumn(info.Name, propertyType)); 
     } 

     foreach (T entity in list) 
     { 
      object[] values = new object[properties.Length]; 
      for (int i = 0; i < properties.Length; i++) 
      { 
       var v = properties[i].GetValue(entity); 
       Type pType = v.GetType().GetGenericArguments().FirstOrDefault(); 

       if (v.GetType().GetGenericTypeDefinition() == typeof(List<>)) 
       { 
        if(pType == typeof(int)) 
         values[i] = (v as List<int>).First(); 
        else if(pType == typeof(string)) 
         values[i] = (v as List<string>).First(); 
       } 
       else 
       { 
        values[i] = v; 
       } 
      } 
      dataTable.Rows.Add(values); 
     } 
     return dataTable; 
    } 

Answer 1

你需要的東西是這樣的：

foreach (PropertyInfo info in properties) 
{ 
    if(info.PropertyType == typeof(IEnumerable)) 
    { 
     dataTable.Columns.Add(new DataColumn(info.Name, info.Cast<object>().First().GetType()); 
    } 
    else 
    { 
     dataTable.Columns.Add(new DataColumn(info.Name, info.PropertyType)); 
    } 
} 

foreach (T entity in list) 
{ 
    object[] values = new object[properties.Length]; 
    for (int i = 0; i < properties.Length; i++) 
    { 
     var v = properties[i].GetValue(entity); 
     if(v is IEnumerable) 
     { 
      values[i] = (v.Cast<object>().First()).First(); 
     } 
     else 
     { 
      values[i] = v; 
     } 
    } 

    dataTable.Rows.Add(values); 
}