This method is to convert the list to a DataTable. I commented the code for you understanding.
public static DataTable ToDataTable<T>(this List<T> iList)
{
DataTable dataTable = new DataTable();
//Creates a new collection and assign it the properties for typeof(T)
PropertyDescriptorCollection propertyDescriptorCollection = TypeDescriptor.GetProperties(typeof(T));
//Traverse this collection
for (int i = 0; i < propertyDescriptorCollection.Count; i++)
{
//Set the PropertyDescriptor
PropertyDescriptor propertyDescriptor = propertyDescriptorCollection[i];
//Get the type of the property
Type type = propertyDescriptor.PropertyType;
//type.IsGenericType represent the current type is a generic type
//type.GetGenericTypeDefinition() return a Type object that represents a generic type definition from which the current generic type can be constructed
//Nullable<> represent a value type that can be assigned null
if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
type = Nullable.GetUnderlyingType(type); //Return the underlying type argument of the specified nullable type.
dataTable.Columns.Add(propertyDescriptor.Name, type); // add propertyDescriptor.Name as the table column name
}
//Define an array
object[] values = new object[propertyDescriptorCollection.Count];
foreach (T iListItem in iList)
{
for (int i = 0; i < values.Length; i++)
{
//Assign the value of the collection propertyDescriptorCollection to value
values[i] = propertyDescriptorCollection[i].GetValue(iListItem);
}
dataTable.Rows.Add(values); //add the values as the table value
}
return dataTable;
}
jsshivalik
how i can call this by passing Sql Query
Can you tell me why call this method by passing sql query? what is its application scenario?
Best regards,
Sam
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As PatriceSc said, using adapter can meet your needs.
private static DataTable dt(DataTable datatable,string connectionString, string queryString)
{
using (SqlConnection connection =new SqlConnection(connectionString))
{
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = new SqlCommand(queryString, connection);
adapter.Fill(datatable);
return datatable;
}
}
The above is the sql database. what should note is what database you are using.
Best regards,
Sam
MSDN Community Support
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I don't quite understand what you mean. Isn't this a variable that declares a DataTable type?
Best regards,
sam
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Generic List
Sep 28, 2019 05:52 AM|jsshivalik|LINK
Hi
How the below code works & how i can call this by passing Sql Query
public static DataTable ToDataTable<T>(this List<T> iList) { DataTable dataTable = new DataTable(); PropertyDescriptorCollection propertyDescriptorCollection = TypeDescriptor.GetProperties(typeof(T)); for (int i = 0; i < propertyDescriptorCollection.Count; i++) { PropertyDescriptor propertyDescriptor = propertyDescriptorCollection[i]; Type type = propertyDescriptor.PropertyType; if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>)) type = Nullable.GetUnderlyingType(type); dataTable.Columns.Add(propertyDescriptor.Name, type); } object[] values = new object[propertyDescriptorCollection.Count]; foreach (T iListItem in iList) { for (int i = 0; i < values.Length; i++) { values[i] = propertyDescriptorCollection[i].GetValue(iListItem); } dataTable.Rows.Add(values); } return dataTable; }Thanks
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Re: Generic List
Sep 30, 2019 08:05 AM|samwu|LINK
Hi jsshivalik,
This method is to convert the list to a DataTable. I commented the code for you understanding.
public static DataTable ToDataTable<T>(this List<T> iList) { DataTable dataTable = new DataTable(); //Creates a new collection and assign it the properties for typeof(T) PropertyDescriptorCollection propertyDescriptorCollection = TypeDescriptor.GetProperties(typeof(T)); //Traverse this collection for (int i = 0; i < propertyDescriptorCollection.Count; i++) { //Set the PropertyDescriptor PropertyDescriptor propertyDescriptor = propertyDescriptorCollection[i]; //Get the type of the property Type type = propertyDescriptor.PropertyType; //type.IsGenericType represent the current type is a generic type //type.GetGenericTypeDefinition() return a Type object that represents a generic type definition from which the current generic type can be constructed //Nullable<> represent a value type that can be assigned null if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>)) type = Nullable.GetUnderlyingType(type); //Return the underlying type argument of the specified nullable type. dataTable.Columns.Add(propertyDescriptor.Name, type); // add propertyDescriptor.Name as the table column name } //Define an array object[] values = new object[propertyDescriptorCollection.Count]; foreach (T iListItem in iList) { for (int i = 0; i < values.Length; i++) { //Assign the value of the collection propertyDescriptorCollection to value values[i] = propertyDescriptorCollection[i].GetValue(iListItem); } dataTable.Rows.Add(values); //add the values as the table value } return dataTable; }Can you tell me why call this method by passing sql query? what is its application scenario?
Best regards,
Sam
Please remember to click "Mark as Answer" the responses that resolved your issue.
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Re: Generic List
Sep 30, 2019 04:47 PM|jsshivalik|LINK
Hi Samwu
Thank but how i will call this method
Thanks
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Re: Generic List
Sep 30, 2019 05:08 PM|PatriceSc|LINK
Hi,
Which db access API are you using ? Some more context could help.
If you want to fill a DataTable using a SQL query you could use https://docs.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqldataadapter?view=netframework-4.8 (this code sample uses a DataSet but you can use the same code with a DataTable instead).
Or do you really want to use for example Entity Framework to fill a list of objects and then fill a DataTable from this list?
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Re: Generic List
Sep 30, 2019 06:23 PM|mgebhard|LINK
The shared snippet is part of an extension method pattern (it's missing the class) that converts a List<T> into a DataTable.
Implementation would look similar to the following.
List<MyType> items = datalayer.getMyItems(); DataTable dt = items.ToDataTable();Extension method reference.
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/extension-methods
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Re: Generic List
Oct 01, 2019 01:43 AM|samwu|LINK
Hi jsshivalik,
As PatriceSc said, using adapter can meet your needs.
private static DataTable dt(DataTable datatable,string connectionString, string queryString) { using (SqlConnection connection =new SqlConnection(connectionString)) { SqlDataAdapter adapter = new SqlDataAdapter(); adapter.SelectCommand = new SqlCommand(queryString, connection); adapter.Fill(datatable); return datatable; } }The above is the sql database. what should note is what database you are using.
Best regards,
Sam
Please remember to click "Mark as Answer" the responses that resolved your issue.
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Re: Generic List
Oct 01, 2019 04:39 AM|jsshivalik|LINK
Hi Samwu
With this i can use only Sql Database . Suppose some other Database is used at later stage then this code may not work.
Secondly how DataTable datatables works
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Re: Generic List
Oct 01, 2019 05:28 AM|samwu|LINK
Hi jsshivalik,
Other databases are similarly written. you can refer to this link:
https://docs.microsoft.com/en-us/dotnet/api/system.data.oledb.oledbdataadapter?view=netframework-4.8
I don't quite understand what you mean. Isn't this a variable that declares a DataTable type?
Best regards,
sam
Please remember to click "Mark as Answer" the responses that resolved your issue.
If you have any compliments or complaints to MSDN Support, feel free to contact MSDNFSF@microsoft.com.