C# 将数据集转换为列表

Convert DataSet to List

提问by iJade

Here is my c# code

这是我的 C# 代码

Employee objEmp = new Employee();
List<Employee> empList = new List<Employee>();
foreach (DataRow dr in ds.Tables[0].Rows)
{
    empList.Add(new Employee { Name = Convert.ToString(dr["Name"]), Age = Convert.ToInt32(dr["Age"]) });
}

It uses a loop to create a List from a dataset.Is there any direct method or shorter method or one line code to convert dataset to list

它使用循环从数据集创建列表。是否有任何直接方法或更短的方法或一行代码将数据集转换为列表

采纳答案by Carra

Try something like this:

尝试这样的事情：

var empList = ds.Tables[0].AsEnumerable()
    .Select(dataRow => new Employee
    {
        Name = dataRow.Field<string>("Name")
    }).ToList();

回答by kostas ch.

Try the above which will run with any list type.

尝试使用任何列表类型运行的上述方法。

  public DataTable ListToDataTable<T>(IList<T> data)
    {
        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, prop.PropertyType);
        }
        object[] values = new object[props.Count];
        foreach (T item in data)
        {
            for (int i = 0; i < values.Length; i++)
            {
                values[i] = props[i].GetValue(item);
            }
            table.Rows.Add(values);
        }
        return table;
    }

回答by Fabian Bigler

var myData = ds.Tables[0].AsEnumerable().Select(r => new Employee {
    Name = r.Field<string>("Name"),
    Age = r.Field<int>("Age")
});
var list = myData.ToList(); // For if you really need a List and not IEnumerable

回答by Nitin Sawant

Here's extension method to convert DataTable to object list:

这是将 DataTable 转换为对象列表的扩展方法：

    public static class Extensions
    {
        public static List<T> ToList<T>(this DataTable table) where T : new()
        {
            IList<PropertyInfo> properties = typeof(T).GetProperties().ToList();
            List<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)
            {
                if (property.PropertyType == typeof(System.DayOfWeek))
                {
                    DayOfWeek day = (DayOfWeek)Enum.Parse(typeof(DayOfWeek), row[property.Name].ToString());
                    property.SetValue(item,day,null);
                }
                else
                {
                    if(row[property.Name] == DBNull.Value)
                        property.SetValue(item, null, null);
                    else 
                        property.SetValue(item, row[property.Name], null); 
                }
            }
            return item;
        }
    }

usage:

用法：

List<Employee> lst = ds.Tables[0].ToList<Employee>();

@itay.b CODE EXPLAINED: We first read all the property names from the class T using reflection
then we iterate through all the rows in datatable and create new object of T,
then we set the properties of the newly created object using reflection.

@itay.b 代码解释：我们首先使用反射从类 T 中读取所有属性名称，
然后遍历数据表中的所有行并创建 T 的新对象，
然后我们使用反射设置新创建对象的属性。

The property values are picked from the row's matching column cell.

属性值是从行的匹配列单元格中选取的。

PS:class property name and table column names must be same

PS：类属性名和表列名必须相同

回答by Qasim Javaid Khan

Try this....modify the code as per your needs.

试试这个....根据您的需要修改代码。

      List<Employee> target = dt.AsEnumerable()
      .Select(row => new Employee
      {
        Name = row.Field<string?>(0).GetValueOrDefault(),
        Age= row.Field<int>(1)
      }).ToList();

回答by Simon Dowdeswell

Fill the dataset with data from, say a stored proc command

用来自存储的 proc 命令的数据填充数据集

DbDataAdapter adapter = DbProviderFactories.GetFactory(cmd.Connection).CreateDataAdapter();
adapter.SelectCommand = cmd;
DataSet ds = new DataSet();
adapter.Fill(ds);

Get The Schema,

获取架构，

string s = ds.GetXmlSchema();

save it to a file say: datasetSchema.xsd. Generate the C# classes for the Schema: (at the VS Command Prompt)

将其保存到一个文件中，例如：datasetSchema.xsd。为架构生成 C# 类：（在 VS 命令提示符处）

xsd datasetSchema.xsd /c

Now, when you need to convert the DataSet data to classes you can deserialize (the default name given to the generated root class is NewDataSet):

现在，当您需要将 DataSet 数据转换为类时，您可以反序列化（生成的根类的默认名称是 NewDataSet）：

public static T Create<T>(string xml)
{
    XmlSerializer serializer = new XmlSerializer(typeof(T));
    using (StringReader reader = new StringReader(xml))
    {
        T t = (T)serializer.Deserialize(reader);

        reader.Close();
        return t;
    }
}

var xml = ds.GetXml();
var dataSetObjects = Create<NewDataSet>(xml);

回答by Jeetendra Negi

                DataSet ds = new DataSet();
                ds = obj.getXmlData();// get the multiple table in dataset.

                Employee objEmp = new Employee ();// create the object of class Employee 
                List<Employee > empList = new List<Employee >();
                int table = Convert.ToInt32(ds.Tables.Count);// count the number of table in dataset
                for (int i = 1; i < table; i++)// set the table value in list one by one
                {
                    foreach (DataRow dr in ds.Tables[i].Rows)
                    {
                        empList.Add(new Employee { Title1 = Convert.ToString(dr["Title"]), Hosting1 = Convert.ToString(dr["Hosting"]), Startdate1 = Convert.ToString(dr["Startdate"]), ExpDate1 = Convert.ToString(dr["ExpDate"]) });
                    }
                }
                dataGridView1.DataSource = empList;

回答by Ajsatis

Use the code below:

使用下面的代码：

using Newtonsoft.Json;
string JSONString = string.Empty;
JSONString = JsonConvert.SerializeObject(ds.Tables[0]);

回答by vivek ramasamy

Add a new class named as "Helper" and change the property of the class to "public static"

添加一个名为“Helper”的新类并将该类的属性更改为“public static”

public static class Helper
{
    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);
                        propertyInfo.SetValue(obj, Convert.ChangeType(row[prop.Name], propertyInfo.PropertyType), null);
                    }
                    catch
                    {
                        continue;
                    }
                }

                list.Add(obj);
            }

            return list;
        }
        catch
        {
            return null;
        }
    }
}

and access this class in your code behind as like below

并在后面的代码中访问此类，如下所示

 DataTable dtt = dsCallList.Tables[0];
 List<CallAssignment> lstCallAssignement = dtt.DataTableToList<CallAssignment>();

回答by anubhav rawat

 List<GSTEntity.gst_jobwork_to_mfgmaster> ListToGetJwToMfData = new List<GSTEntity.gst_jobwork_to_mfgmaster>();
            DataSet getJwtMF = new DataSet();
            getJwtMF = objgst_jobwork_to_mfgmaster_BLL.GetDataJobWorkToMfg(AssesseeId, PremiseId,  Fyear,  MonthId, out webex);
            if(getJwtMF.Tables["gst_jobwork_to_mfgmaster"] != null)
            {

                ListToGetJwToMfData = (from master in getJwtMF.Tables["gst_jobwork_to_mfgmaster"].AsEnumerable() select new GSTEntity.gst_jobwork_to_mfgmaster { Partygstin = master.Field<string>("Partygstin"), Partystate =
                                       master.Field<string>("Partystate"), NatureOfTransaction = master.Field<string>("NatureOfTransaction"), ChallanNo = master.Field<string>("ChallanNo"), ChallanDate=master.Field<int>("ChallanDate"),  OtherJW_ChallanNo=master.Field<string>("OtherJW_ChallanNo"),   OtherJW_ChallanDate = master.Field<int>("OtherJW_ChallanDate"),
                    OtherJW_GSTIN=master.Field<string>("OtherJW_GSTIN"),
                    OtherJW_State = master.Field<string>("OtherJW_State"),
                    InvoiceNo = master.Field<string>("InvoiceNo"),
                    InvoiceDate=master.Field<int>("InvoiceDate"),
                    Description =master.Field<string>("Description"),
                    UQC= master.Field<string>("UQC"),
                    qty=master.Field<decimal>("qty"),
                    TaxValue=master.Field<decimal>("TaxValue"),
                    Id=master.Field<int>("Id")                        

                }).ToList();