Solved

how to generate datatable from linq query?

Posted on 2011-03-13
3
718 Views
Last Modified: 2013-12-17
hi,

I am trying to select data from datatable using linq, now the problem I want to put selected data in datatable schema, I found a ready class to create datatable from implemented IEnumerable returned query, but that generate errors, so how can I create datatable from that query?

here is my try:

 
private DataTable GetInvoicesForCustomer(string id)
        {
            var invoices = (from invoice in dtCustomersInvoices.AsEnumerable()
                            where invoice.Field<int>("id").ToString() == id
                            select invoice);
            if (invoices == null) return null;
            DataTable dt = invoices.CreateDataTable("SelectedInvoicesTable");
            return null;
        }

Open in new window


 
public static class HelperUtils
    {
        // From the Book Programming Microsoft Linq in Microsoft .Net Framework 4
        // By Paolo Pialorsi and Marco Russo
        public static DataTable CreateDataTable<T>(this IEnumerable<T> query, string tableName)
        {
            DataTable table = new DataTable(tableName);
            var fields = typeof(T).GetProperties();

            // Create Columns
            foreach (var field in fields)
            {
                DataColumn column = new DataColumn(field.Name);

                //column.AllowDBNull = (typeof(T).IsSubclassOf(typeof(ValueType))) 
                //    ? IsNullableType(typeof(T)) 
                //    : true;

                // This line modified from original the original line is above
                column.AllowDBNull = (typeof(T).IsSubclassOf(typeof(ValueType)))
                    ? (typeof(T).IsGenericType && typeof(T).GetGenericTypeDefinition() == typeof(Nullable<>))
                    : true;
                table.Columns.Add(column);
            }

            // Copy rows
            foreach (var row in query)
            {
                object[] values = new object[fields.Length];
                for (int i = 0; i < values.Length; i++)
                {
                    values[i] = fields[i].GetValue(row, null);
                }
                table.Rows.Add(values);
            }
            return table;
        }
    }

Open in new window



any help please?
0
Comment
Question by:njgroup
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 35121757
Would this be simpler?
private DataTable GetInvoicesForCustomer(string id)
{
    DataTable invoices = (from invoice in dtCustomersInvoices.AsEnumerable()
                          where invoice.Field<int>("id").ToString() == id
                          select invoice).AsDataview().Table;
}

Open in new window

0
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 35121759
That should be "AsDataView()", with a capital "V".
0
 
LVL 5

Accepted Solution

by:
vivekpv10 earned 500 total points
ID: 35127260
for converting linq result into a datatable,use this function..
eg.
var drevlinq = from drelinq_obj in context.drev where userid == drelinq_obj.user_master.user_id select new { drelinq_obj.dreid };
 DataTable devtab = LINQToDataTable(drevlinq);
Public DataTable LINQToDataTable<T>(System.Collections.Generic.IEnumerable<T> varlist)
    {
        DataTable dtReturn = new DataTable();

        // column names 
        PropertyInfo[] oProps = null;

        if (varlist == null) return dtReturn;
    

        foreach (T rec in varlist)
        {
            // Use reflection to get property names, to create table, Only first time, others 
            //   will follow 
            if (oProps == null)
            {
                oProps = ((Type)rec.GetType()).GetProperties();
                foreach (PropertyInfo pi in oProps)
                {
                    Type colType = pi.PropertyType;

                    if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition()
                    == typeof(Nullable<>)))
                    {
                        colType = colType.GetGenericArguments()[0];
                    }

                    dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
                }
            }

            DataRow dr = dtReturn.NewRow();

            foreach (PropertyInfo pi in oProps)
            {
                dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue
                (rec, null);
            }

            dtReturn.Rows.Add(dr);
        }
        return dtReturn;
    }

Open in new window

0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article describes relatively difficult and non-obvious issues that are likely to arise when creating COM class in Visual Studio and deploying it by professional MSI-authoring tools. It is assumed that the reader is already familiar with the cla…
Calculating holidays and working days is a function that is often needed yet it is not one found within the Framework. This article presents one approach to building a working-day calculator for use in .NET.
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
NetCrunch network monitor is a highly extensive platform for network monitoring and alert generation. In this video you'll see a live demo of NetCrunch with most notable features explained in a walk-through manner. You'll also get to know the philos…

615 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question