198

目前，我正在使用：

DataTable dt = CreateDataTableInSomeWay();

List<DataRow> list = new List<DataRow>(); 
foreach (DataRow dr in dt.Rows)
{
    list.Add(dr);
}

有没有更好/神奇的方法？

4

27 回答 27

296

如果您使用的是 .NET 3.5，则可以使用DataTableExtensions.AsEnumerable(一种扩展方法)，然后如果您真的需要 aList<DataRow>而不仅仅是IEnumerable<DataRow>您可以调用Enumerable.ToList：

IEnumerable<DataRow> sequence = dt.AsEnumerable();

或者

using System.Linq;
...
List<DataRow> list = dt.AsEnumerable().ToList();
于 2008-10-16T13:59:01.580 回答
70 
List<Employee> emp = new List<Employee>();

//Maintaining DataTable on ViewState
//For Demo only

DataTable dt = ViewState["CurrentEmp"] as DataTable;

//read data from DataTable 
//using lamdaexpression


emp = (from DataRow row in dt.Rows

   select new Employee
   {
       _FirstName = row["FirstName"].ToString(),
       _LastName = row["Last_Name"].ToString()

   }).ToList();
于 2011-12-15T18:44:19.060 回答
38

使用 C# 3.0 和 System.Data.DataSetExtensions.dll，

List<DataRow> rows = table.Rows.Cast<DataRow>().ToList();
于 2008-10-16T13:28:03.530 回答
34

你可以使用

List<DataRow> list = new List<DataRow>(dt.Select());

dt.Select()将返回表中的所有行，作为数据行数组，并且List构造函数接受该对象数组作为初始填充列表的参数。

于 2008-10-16T13:26:16.887 回答
17

您可以将扩展功能创建为：

public static List<T> ToListof<T>(this DataTable dt)
{
    const BindingFlags flags = BindingFlags.Public | BindingFlags.Instance;
    var columnNames = dt.Columns.Cast<DataColumn>()
        .Select(c => c.ColumnName)
        .ToList();
    var objectProperties = typeof(T).GetProperties(flags);
    var targetList = dt.AsEnumerable().Select(dataRow =>
    {
        var instanceOfT = Activator.CreateInstance<T>();

        foreach (var properties in objectProperties.Where(properties => columnNames.Contains(properties.Name) && dataRow[properties.Name] != DBNull.Value))
        {
            properties.SetValue(instanceOfT, dataRow[properties.Name], null);
        }
        return instanceOfT;
    }).ToList();

    return targetList;
}


var output = yourDataInstance.ToListof<targetModelType>();
于 2015-04-26T12:21:11.700 回答
16

如果您只想返回“ID” int 字段中的值列表，您可以使用...

List<int> ids = (from row in dt.AsEnumerable() select Convert.ToInt32(row["ID"])).ToList();
于 2012-10-10T14:56:46.627 回答
15

我已经从这个答案（ https://stackoverflow.com/a/24588210/4489664 ）中添加了一些修改代码，因为对于可为空的类型，它将返回异常

public static List<T> DataTableToList<T>(this DataTable table) where T: new()
{
    List<T> list = new List<T>();
    var typeProperties = typeof(T).GetProperties().Select(propertyInfo => new
        {
            PropertyInfo = propertyInfo,
            Type = Nullable.GetUnderlyingType(propertyInfo.PropertyType) ?? propertyInfo.PropertyType
        }).ToList();

    foreach (var row in table.Rows.Cast<DataRow>())
    {
        T obj = new T();
        foreach (var typeProperty in typeProperties)
        {
            object value = row[typeProperty.PropertyInfo.Name];
            object safeValue = value == null || DBNull.Value.Equals(value)
                ? null
                : Convert.ChangeType(value, typeProperty.Type);

            typeProperty.PropertyInfo.SetValue(obj, safeValue, null);
        }
        list.Add(obj);
    }
    return list;
}
于 2015-04-14T11:13:04.633 回答
11 
using System.Data;


var myEnumerable = myDataTable.AsEnumerable();

List<MyClass> myClassList =
    (from item in myEnumerable
     select new MyClass{
         MyClassProperty1 = item.Field<string>("DataTableColumnName1"),
         MyClassProperty2 = item.Field<string>("DataTableColumnName2")
    }).ToList();
于 2012-07-31T06:00:38.880 回答
6

同样，使用 3.5 你可以这样做：

dt.Select().ToList()

BRGDS

于 2010-03-15T13:17:00.460 回答
5 
// this is better suited for expensive object creation/initialization
IEnumerable<Employee> ParseEmployeeTable(DataTable dtEmployees)
{
    var employees = new ConcurrentBag<Employee>();

    Parallel.ForEach(dtEmployees.AsEnumerable(), (dr) =>
    {
        employees.Add(new Employee() 
        {
            _FirstName = dr["FirstName"].ToString(),
            _LastName = dr["Last_Name"].ToString()
        });
    });

    return employees;
}
于 2013-07-23T19:59:59.237 回答
4

一种更“神奇”的方式，不需要 .NET 3.5。

例如，如果DBDatatable返回一列 Guids（SQL 中的唯一标识符），那么您可以使用：

Dim gList As New List(Of Guid)
gList.AddRange(DirectCast(DBDataTable.Select(), IEnumerable(Of Guid)))
于 2009-03-30T15:59:08.263 回答
3

DataTable.Select()没有按照它们在数据表中出现的顺序给出行。

如果顺序很重要，我觉得迭代数据行集合并形成一个列表是正确的方法，或者您也可以使用DataTable.Select(string filterexpression, string sort).

但是这种重载可能无法处理 SQL 提供的所有排序（如按大小写排序...）。

于 2009-07-09T09:52:33.660 回答
3 
DataTable dt;   // datatable should contains datacolumns with Id,Name

List<Employee> employeeList=new List<Employee>();  // Employee should contain  EmployeeId, EmployeeName as properties

foreach (DataRow dr in dt.Rows)
{
    employeeList.Add(new Employee{EmployeeId=dr.Id,EmplooyeeName=dr.Name});
}
于 2012-12-06T05:47:40.030 回答
2 
        /* This is a generic method that will convert any type of DataTable to a List 
         * 
         * 
         * Example :    List< Student > studentDetails = new List< Student >();  
         *              studentDetails = ConvertDataTable< Student >(dt);  
         *
         * Warning : In this case the DataTable column's name and class property name
         *           should be the same otherwise this function will not work properly
         */

下面是两个函数，如果我们传递一个 DataTable 和一个用户定义的类。然后它将返回该类的列表以及 DataTable 数据。

        public static List<T> ConvertDataTable<T>(DataTable dt)
        {
            List<T> data = new List<T>();
            foreach (DataRow row in dt.Rows)
            {
                T item = GetItem<T>(row);
                data.Add(item);
            }
            return data;
        }


        private static T GetItem<T>(DataRow dr)
        {
            Type temp = typeof(T);
            T obj = Activator.CreateInstance<T>();

            foreach (DataColumn column in dr.Table.Columns)
            {
                foreach (PropertyInfo pro in temp.GetProperties())
                {
                   //in case you have a enum/GUID datatype in your model
                   //We will check field's dataType, and convert the value in it.
                    if (pro.Name == column.ColumnName){                
                    try
                    {
                        var convertedValue = GetValueByDataType(pro.PropertyType, dr[column.ColumnName]);
                        pro.SetValue(obj, convertedValue, null);
                    }
                    catch (Exception e)
                    {         
                       //ex handle code                   
                        throw;
                    }
                        //pro.SetValue(obj, dr[column.ColumnName], null);
                }
                    else
                        continue;
                }
            }
            return obj;
        }

此方法将检查字段的数据类型，并将 dataTable 值转换为该数据类型。

    private static object GetValueByDataType(Type propertyType, object o)
    {
        if (o.ToString() == "null")
        {
            return null;
        }
        if (propertyType == (typeof(Guid)) || propertyType == typeof(Guid?))
        {
            return Guid.Parse(o.ToString());
        }
        else if (propertyType == typeof(int) || propertyType.IsEnum) 
        {
            return Convert.ToInt32(o);
        }
        else if (propertyType == typeof(decimal) )
        {
            return Convert.ToDecimal(o);
        }
        else if (propertyType == typeof(long))
        {
            return Convert.ToInt64(o);
        }
        else if (propertyType == typeof(bool) || propertyType == typeof(bool?))
        {
            return Convert.ToBoolean(o);
        }
        else if (propertyType == typeof(DateTime) || propertyType == typeof(DateTime?))
        {
            return Convert.ToDateTime(o);
        }
        return o.ToString();
    }

要调用上述方法，请使用以下语法：

List< Student > studentDetails = new List< Student >();  
studentDetails = ConvertDataTable< Student >(dt);

根据您的要求更改 Student 类名称和 dt 值。在这种情况下，DataTable 列的名称和类属性名称应该相同，否则此函数将无法正常工作。

于 2018-01-30T09:36:26.100 回答
2

将 DataTable 转换为类的通用列表的最简单方法

使用 Newtonsoft.Json；

var json = JsonConvert.SerializeObject(dataTable);
var model = JsonConvert.DeserializeObject<List<ClassName>>(json);
于 2020-01-23T12:49:56.653 回答
1

使用System.Data命名空间然后你会得到.AsEnumerable().

于 2015-04-20T06:34:21.787 回答
1 
lPerson = dt.AsEnumerable().Select(s => new Person()
        {
            Name = s.Field<string>("Name"),
            SurName = s.Field<string>("SurName"),
            Age = s.Field<int>("Age"),
            InsertDate = s.Field<DateTime>("InsertDate")
        }).ToList();

链接到工作DotNetFiddle 示例

    using System;
    using System.Collections.Generic;   
    using System.Data;
    using System.Linq;
    using System.Data.DataSetExtensions;

    public static void Main()
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("Name", typeof(string));
        dt.Columns.Add("SurName", typeof(string));
        dt.Columns.Add("Age", typeof(int));
        dt.Columns.Add("InsertDate", typeof(DateTime));

        var row1= dt.NewRow();
        row1["Name"] = "Adam";
        row1["SurName"] = "Adam";
        row1["Age"] = 20;
        row1["InsertDate"] = new DateTime(2020, 1, 1);
        dt.Rows.Add(row1);

        var row2 = dt.NewRow();
        row2["Name"] = "John";
        row2["SurName"] = "Smith";
        row2["Age"] = 25;
        row2["InsertDate"] = new DateTime(2020, 3, 12);
        dt.Rows.Add(row2);

        var row3 = dt.NewRow();
        row3["Name"] = "Jack";
        row3["SurName"] = "Strong";
        row3["Age"] = 32;
        row3["InsertDate"] = new DateTime(2020, 5, 20);
        dt.Rows.Add(row3);

        List<Person> lPerson = new List<Person>();
        lPerson = dt.AsEnumerable().Select(s => new Person()
        {
            Name = s.Field<string>("Name"),
            SurName = s.Field<string>("SurName"),
            Age = s.Field<int>("Age"),
            InsertDate = s.Field<DateTime>("InsertDate")
        }).ToList();
        
        foreach(Person pers in lPerson)
        {
            Console.WriteLine("{0} {1} {2} {3}", pers.Name, pers.SurName, pers.Age, pers.InsertDate);
        }
    }   
    
    public class Person
    {
        public string Name { get; set; }
        public string SurName { get; set; }
        public int Age { get; set; }
        public DateTime InsertDate { get; set; }
    }
}
于 2020-05-06T13:12:39.987 回答
0

这对我有用： 至少需要 .Net Framework 3.5， 下面的代码显示 DataRow 转为 Generic.IEnumerable，comboBox1 已用于更好的说明。 

using System.Linq;

DataTable dt = new DataTable();            
dt = myClass.myMethod();                 
List<object> list = (from row in dt.AsEnumerable() select (row["name"])).ToList();
comboBox1.DataSource = list;
于 2014-09-02T13:26:15.667 回答
0

输出

public class ModelUser
{
    #region Model

    private string _username;
    private string _userpassword;
    private string _useremail;
    private int _userid;

    /// <summary>
    /// 
    /// </summary>
    public int userid
    {
        set { _userid = value; }
        get { return _userid; }
    }


    /// <summary>
    /// 
    /// </summary>

    public string username
    {
        set { _username = value; }
        get { return _username; }
    }

    /// <summary>
    /// 
    /// </summary>
    public string useremail
    {
        set { _useremail = value; }
        get { return _useremail; }
    }

    /// <summary>
    /// 
    /// </summary>
    public string userpassword
    {
        set { _userpassword = value; }
        get { return _userpassword; }
    }
    #endregion Model
}

public List<ModelUser> DataTableToList(DataTable dt)
{
    List<ModelUser> modelList = new List<ModelUser>();
    int rowsCount = dt.Rows.Count;
    if (rowsCount > 0)
    {
        ModelUser model;
        for (int n = 0; n < rowsCount; n++)
        {
            model = new ModelUser();

            model.userid = (int)dt.Rows[n]["userid"];
            model.username = dt.Rows[n]["username"].ToString();
            model.useremail = dt.Rows[n]["useremail"].ToString();
            model.userpassword = dt.Rows[n]["userpassword"].ToString();

            modelList.Add(model);
        }
    }
    return modelList;
}

static DataTable GetTable()
{
    // Here we create a DataTable with four columns.
    DataTable table = new DataTable();
    table.Columns.Add("userid", typeof(int));
    table.Columns.Add("username", typeof(string));
    table.Columns.Add("useremail", typeof(string));
    table.Columns.Add("userpassword", typeof(string));

    // Here we add five DataRows.
    table.Rows.Add(25, "Jame", "Jame@hotmail.com", DateTime.Now.ToString());
    table.Rows.Add(50, "luci", "luci@hotmail.com", DateTime.Now.ToString());
    table.Rows.Add(10, "Andrey", "Andrey@hotmail.com", DateTime.Now.ToString());
    table.Rows.Add(21, "Michael", "Michael@hotmail.com", DateTime.Now.ToString());
    table.Rows.Add(100, "Steven", "Steven@hotmail.com", DateTime.Now.ToString());
    return table;
}

protected void Page_Load(object sender, EventArgs e)
{
    List<ModelUser> userList = new List<ModelUser>();

    DataTable dt = GetTable();

    userList = DataTableToList(dt);

    gv.DataSource = userList;
    gv.DataBind();
}[enter image description here][1]


</asp:GridView>
</div>
于 2016-02-07T09:01:22.840 回答
0

我们可以使用通用方法来转换DataTable为，List而不是手动将 a 转换DataTable为List。

注意：DataTable'sColumnName和Type'sPropertyName应该相同。

调用以下方法：

long result = Utilities.ConvertTo<Student>(dt ,out listStudent);

// Generic Method
public class Utilities
{
    public static long ConvertTo<T>(DataTable table, out List<T> entity)
    {
        long returnCode = -1;
        entity = null;

        if (table == null)
        {
            return -1;
        }

        try
        {
            entity = ConvertTo<T>(table.Rows);
            returnCode = 0;
        }

        catch (Exception ex)
        {
            returnCode = 1000;
        }

        return returnCode;
    }

    static List<T> ConvertTo<T>(DataRowCollection rows)
    {
        List<T> list = null;
        if (rows != null)
        {
            list = new List<T>();

            foreach (DataRow row in rows)
            {
                T item = CreateItem<T>(row);
                list.Add(item);
            }
        }

        return list;
    }

    static T CreateItem<T>(DataRow row)
    {
        string str = string.Empty;
        string strObj = string.Empty;

        T obj = default(T);

        if (row != null)
        {
            obj = Activator.CreateInstance<T>();
            strObj = obj.ToString();
            NameValueCollection objDictionary = new NameValueCollection();

            foreach (DataColumn column in row.Table.Columns)
            {
                PropertyInfo prop = obj.GetType().GetProperty(column.ColumnName);

                if (prop != null)
                {
                    str = column.ColumnName;

                    try
                    {
                        objDictionary.Add(str, row[str].ToString());
                        object value = row[column.ColumnName];
                        Type vType = obj.GetType();

                        if (value == DBNull.Value)
                        {
                            if (vType == typeof(int) || vType == typeof(Int16)
                                                     || vType == typeof(Int32)
                                                     || vType == typeof(Int64)
                                                     || vType == typeof(decimal)
                                                     || vType == typeof(float)
                                                     || vType == typeof(double))
                            {
                                value = 0;
                            }

                            else if (vType == typeof(bool))
                            {
                                value = false;
                            }

                            else if (vType == typeof(DateTime))
                            {
                                value = DateTime.MaxValue;
                            }

                            else
                            {
                                value = null;
                            }

                            prop.SetValue(obj, value, null);
                        }

                        else
                        {
                            prop.SetValue(obj, value, null);
                        }
                    }

                    catch(Exception ex)
                    {

                    }
                }
            }

            PropertyInfo ActionProp = obj.GetType().GetProperty("ActionTemplateValue");

            if (ActionProp != null)
            {
                object ActionValue = objDictionary;
                ActionProp.SetValue(obj, ActionValue, null);
            }
        }

        return obj;
    }
}
于 2016-03-10T11:58:18.400 回答
0

您可以将数据表用于通用列表的通用方法

public static List<T> DataTableToList<T>(this DataTable table) where T : class, new()
{
    try
    {
        List<T> list = new List<T>();

        foreach (var row in table.AsEnumerable())
        {
            T obj = new T();

            foreach (var prop in obj.GetType().GetProperties())
            {
                try
                {
                    PropertyInfo propertyInfo = obj.GetType().GetProperty(prop.Name);
                    if (propertyInfo.PropertyType.IsEnum)
                    {
                        propertyInfo.SetValue(obj, Enum.Parse(propertyInfo.PropertyType, row[prop.Name].ToString()));
                    }
                    else
                    {
                        propertyInfo.SetValue(obj, Convert.ChangeType(row[prop.Name], propertyInfo.PropertyType), null);
                    }                          
                }
                catch
                {
                    continue;
                }
            }

            list.Add(obj);
        }

        return list;
    }
    catch
    {
        return null;
    }
}
于 2018-09-18T16:03:38.967 回答
0

转换DataTable为通用Dictionary 

public static Dictionary<object,IList<dynamic>> DataTable2Dictionary(DataTable dt)
{
    Dictionary<object, IList<dynamic>> dict = new Dictionary<dynamic, IList<dynamic>>();

    foreach(DataColumn column in dt.Columns)
    {
        IList<dynamic> ts = dt.AsEnumerable()
                              .Select(r => r.Field<dynamic>(column.ToString()))
                              .ToList();
        dict.Add(column, ts);
    }
    return dict;
}
于 2019-06-06T06:44:51.260 回答
0

使用扩展：

public static class Extensions
{
    #region Convert Datatable To List
    public static IList<T> ToList<T>(this DataTable table) where T : new()
    {
        IList<PropertyInfo> properties = typeof(T).GetProperties().ToList();
        IList<T> result = new List<T>();

        foreach (var row in table.Rows)
        {
            var item = CreateItemFromRow<T>((DataRow)row, properties);
            result.Add(item);
        }
        return result;
    }
    private static T CreateItemFromRow<T>(DataRow row, IList<PropertyInfo> properties) where T : new()
    {
        T item = new T();
        foreach (var property in properties)
        {
            property.SetValue(item, row[property.Name], null);
        }
        return item;
    }
    #endregion
}
于 2019-11-17T10:28:26.747 回答
0

将 DataTable 行分配给类的通用列表

  List<Candidate> temp = new List<Candidate>();//List that holds the Candidate Class,
    //Note:The Candidate class contains RollNo,Name and Department
    //tb is DataTable
    temp = (from DataRow dr in tb.Rows
                        select new Candidate()
                        {
                            RollNO = Convert.ToInt32(dr["RollNO"]),
                            Name = dr["Name"].ToString(),
                            Department = dr["Department"].ToString(),

                        }).ToList();
于 2019-12-19T10:28:55.003 回答
0

您可以使用以下两个通用函数

private static List<T> ConvertDataTable<T>(DataTable dt)
    {
        List<T> data = new List<T>();
        foreach (DataRow row in dt.Rows)
        {
            T item = GetItem<T>(row);
            data.Add(item);
        }
        return data;
    }
    private static T GetItem<T>(DataRow dr)
    {

        Type temp = typeof(T);
        T obj = Activator.CreateInstance<T>();

        foreach (DataColumn column in dr.Table.Columns)
        {
            foreach (PropertyInfo pro in temp.GetProperties())
            {
                if (pro.Name == column.ColumnName)
                    pro.SetValue(obj, dr[column.ColumnName].ToString(), null);
                else
                    continue;
            }
        }
        return obj;
    }

并按如下方式使用

List<StudentScanExamsDTO> studentDetails = ConvertDataTable<StudentScanExamsDTO>(dt);
于 2020-01-29T12:10:16.563 回答
0

如果有人想创建自定义函数将数据表转换为列表

class Program
{
    static void Main(string[] args)
    {
        DataTable table = GetDataTable();
        var sw = new Stopwatch();

        sw.Start();
        LinqMethod(table);
        sw.Stop();
        Console.WriteLine("Elapsed time for Linq Method={0}", sw.ElapsedMilliseconds);

        sw.Reset();

        sw.Start();
        ForEachMethod(table);
        sw.Stop();
        Console.WriteLine("Elapsed time for Foreach method={0}", sw.ElapsedMilliseconds);

        Console.ReadKey();
    }

    private static DataTable GetDataTable()
    {
        var table = new DataTable();
        table.Columns.Add("ID", typeof(double));
        table.Columns.Add("CategoryName", typeof(string));
        table.Columns.Add("Active", typeof(double));

        var rand = new Random();

        for (int i = 0; i < 100000; i++)
        {
            table.Rows.Add(i, "name" + i,  rand.Next(0, 2));
        }
        return table;
    }

    private static void LinqMethod(DataTable table)
    {
        var list = table.AsEnumerable()
            .Skip(1)
            .Select(dr =>
                new Category
                {
                    Id = Convert.ToInt32(dr.Field<double>("ID")),
                    CategoryName = dr.Field<string>("CategoryName"),                      
                    IsActive =
                            dr.Field<double>("Active") == 1 ? true : false
                }).ToList();
    }
    private static void ForEachMethod(DataTable table)
    {
        var categoryList = new List<Category>(table.Rows.Count);
        foreach (DataRow row in table.Rows)
        {
            var values = row.ItemArray;
            var category = new Category()
            {
                Id = Convert.ToInt32(values[0]),
                CategoryName = Convert.ToString(values[1]),                   
                IsActive = (double)values[2] == 1 ? true : false
            };
            categoryList.Add(category);
        }
    }

    private class Category
    {
        public int Id { get; set; }
        public string CategoryName { get; set; }
        public bool IsActive { get; set; }
    }
}

如果我们执行上面的代码，Foreach 方法在 56 毫秒内完成，而 linq 方法需要 101 毫秒（对于 1000 条记录）。所以 Foreach 方法更好用。资料来源：C#中将数据表转换为列表的方法（附性能测试示例）

于 2020-10-23T15:48:22.523 回答
0

使用 Newtonsoft Json 试试这个：

var json = JsonConvert.SerializeObject(dataTable);
var YourConvertedDataType = JsonConvert.DeserializeObject<YourDataType>(json);
于 2021-10-30T11:16:47.193 回答