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how to generate datatable from linq query?

Posted on 2011-03-13
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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;
        }

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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;
        }
    }

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any help please?
0
Comment
Question by:njgroup
  • 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;
}

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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 2000 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;
    }

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