c# - Datatable group by issue r.Field<T> -

-

i searching datatable group option , found solution in stackoverflow.

datatable t = // var groups = t.asenumerable()     .groupby(r => r.field<t>("columnname"))

what mean... r.field<t>. why field<t>?
can't here specify r.field<customer>.

read http://blogs.msdn.com/b/adonet/archive/2007/02/05/type-safety-linq-to-datasets-part-2.aspx

edited:

1) why field?

field<t> method : datatable not typed one,the values saved object. field method returns value of column generic type parameter, enable type checking.

if typed datatable can field<customer.id>

    -

Comments

Post a Comment

Popular posts from this blog

c# - how to write client side events functions for the combobox items -

-
<dx:aspxcombobox id="aspxcombobox2" runat="server" clientidmode="autoid" selectedindex="-1" onselectedindexchanged="aspxcombobox1_selectedindexchanged1" > <clientsideevents selectedindexchanged="function(s, e) { grid.selectrows();}" /> <items> <dx:listedititem text="selecte rows" /> <dx:listedititem text="unselectall" /> </items> </dx:aspxcombobox> i want write event "unselect all" item in combobox. how can this? you'll need write javascript function iterates thru combo-box , marks selected items false. see select/unselect checkbox fields using pure javascript , html sample code msdn:
Read more

exception - Python, pyPdf OCR error: pyPdf.utils.PdfReadError: EOF marker not found -

-
pypdf throws exception: pypdf.utils.pdfreaderror: eof marker not found i don't need fix pypdf, need eof error cause "except" block execute , skip on file, doesn't work. still causes program stop running. background: batch ocr program pdfs python, pypdf, adobe pdf ocr error: unsupported filter /lzwdecode ... saga continues. i got 10,000 pdfs in folder. ocrd, not. can't tell 'em apart. step 1 figure out ones not ocrd , ocr (see other threads details). so i'm using pypdf. exceptions related unrecognized characters , unsupported filters when try read text. guestimated if throws exception, it's got text in , doens't go in list. problem solved, right? so: pypdf import pdffilewriter, pdffilereader import sys, os, pypdf, re path = 'c:\users\homer\documents\my pdfs' filelist = os.listdir(path) has_text_list = [] does_not_have_text_list = [] pdf_name in filelist: pdf_file
Read more