• 0

How to save ArrayList object to ViewState?


Question

//for example

[serializable]

class MyItem

{

public string = "";

}

I created several MyItem objects and saved them to an ArrayList "al". Then I store the arraylist to ViewState

ViewState["Items"] = al;

When the page postback, I retrieve the arraylist

ArrayList al = (ArrayList)ViewState["Items"];

But there are nothing in al. Why?

5 answers to this question

Recommended Posts

  • 0
  LRoling said:
Is there a specific reason you are using the ViewState? Couldn't you just Session the data?

I want to design a simple search page, when the search is done, you must display the results, so I want to save the results to a Arraylist that I can display them again without reconnect the database when the page postpack. Do you have any other good plans? thanks.

  • 0
  zhwcn said:
I want to design a simple search page, when the search is done, you must display the results, so I want to save the results to a Arraylist that I can display them again without reconnect the database when the page postpack. Do you have any other good plans? thanks.

Use either Session or System.Web.Caching.Cache. Don't use the ViewState if you can avoid it.

  • 0

The question is: when are you storing your ArrayList in ViewState and when are you trying to access the stored value again? Could be that the ViewState is not yet initialized when you're trying to access it to fetch the ArrayList.

If you're using Visual Studio you could try to debug and step through your code to ensure that things are done in correct order (ASP.NET Page Life Cycle).

  • 0
  jpalo said:
The question is: when are you storing your ArrayList in ViewState and when are you trying to access the stored value again? Could be that the ViewState is not yet initialized when you're trying to access it to fetch the ArrayList.

If you're using Visual Studio you could try to debug and step through your code to ensure that things are done in correct order (ASP.NET Page Life Cycle).

yeah, you are right. I modified my code, put the viewstate retrieve block into OnLoad(), this time it works as I expect. Thank U!

This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • A few things I am wondering about for S3: A.  What's Pike doo gonna look like this time around....yea I've watched the trailers & it looks poofed up, but still.... B. When will the unintelligible, physco-babbling Pelia go away (or at least learn how to speak English properly, without that crappy, slurred accent that sounds like she's on crack, Mary Jane, & LSD at the same time) ?  Hopefully Scotty's arrival will mean her departure is near.... C.  When do we get to see more of the stunningly gorgeous No. 1, preferably in regular/civilian clothes that show off her physical attributes better ? D. Is Spock EVER gonna get laid properly, human style ?  I feel certain that Christine could make any Vulcan-human horizontal bomp a thing to remember for a LONG time  E.  Can we PLEEEEEEZE get rid of the hatchet-head/buzz cut hair styles on Ortega & anyone else that has it....  But otherwise, as Pike says:  HIT IT !  
    • RIP Hotlips..... IMHO, her best scenes were the few where she dared to let her REAL feminine side show through from underneath all that crappy, worn-torn soldier facade that she had to keep up with...she instantly lit up every room or situation where she was featured !
    • Helium Converter 3.3.69.0 by Razvan Serea Helium Converter is a free Windows utility for converting audio files between formats such as MP3, FLAC, AAC, WMA, OGG, and WAV. It supports batch conversion, preserves or updates tag information, and offers features like volume normalization. With a simple interface, it's ideal for users who need to convert large music libraries quickly and efficiently while retaining metadata. Helium Converter key features: Supports file formats: MP3, MP4, FLAC, AAC, M4A, WMA, WAV, OGG, OPUS, APE.... Batch conversion for large music libraries Preserves and edits metadata (ID3, Vorbis Comments, etc.) Volume normalization to equalize loudness Album art extraction and embedding Drag-and-drop interface for quick file selection Adjustable encoding parameters (bitrate, sample rate, channels) Uses internal codecs for consistent performance Supports CUE sheets for split track conversion File renaming based on tags during export Unicode support for international file and tag names Logging of conversion processes for troubleshooting Multi-core CPU support for faster conversions Download: Helium Converter 3.3.69.0 | 25.1 MB (Freeware) Links: Helium Converter Home Page | Screenshot Get alerted to all of our Software updates on Twitter at @NeowinSoftware
    • Since it's been quite a while since the last episode aired, would it be fair (or cruel) to refer to Peggy as a MILF, or even a SMILF ?  HAHAHAHAHAHA
    • Their computers are not gonna stop working in October
  • Recent Achievements

    • One Year In
      WaynesWorld earned a badge
      One Year In
    • First Post
      chriskinney317 earned a badge
      First Post
    • Week One Done
      Nullun earned a badge
      Week One Done
    • First Post
      sultangris earned a badge
      First Post
    • Reacting Well
      sultangris earned a badge
      Reacting Well
  • Popular Contributors

    1. 1
      +primortal
      172
    2. 2
      ATLien_0
      124
    3. 3
      snowy owl
      121
    4. 4
      Xenon
      118
    5. 5
      +Edouard
      93
  • Tell a friend

    Love Neowin? Tell a friend!