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list control - how do I only show image if one saved in record?

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  • list control - how do I only show image if one saved in record?


    Thanks for taking a look.
    We have a list control that is pointing to a table. One of the fields in the table is a blob (image).
    How do I get the list control to only display an image if one was saved for that record?

    At the moment, the list will display the space for the image even if one wasn't saved for that record.



  • #2
    Re: list control - how do I only show image if one saved in record?

    The easiest thing to do would be to put a default image in the blob - even if that default image is an image that says "no image".

    Alternatively, you could put a show/hide on the control's display. Something like controlname > ''

    However, I've had that not work for me before.

    You might have to add a Boolean field that you set to 1 if there is an image to display and 0 if there is no image. The do the show hide off of that field.


    • #3
      Re: list control - how do I only show image if one saved in record?

      There are so many variations concerning the List control and images. This example was built with a List, SQL source, BLOB field.

      The BLOB field, SheetImageThumb, in the List, has a Client-side inline style of width:300px;height:300px; This is just to make the control big to ensure we're getting what we want.

      As well, under Image Properties, Embed Image into HTML is checked.

      Using the List control event onItemDraw, we get access to each row as the List is put together. This code...

      if(data.SheetImageThumb == null){
      	$('{dialog.ComponentName}.LISTIMAGES.SHEETIMAGETHUMB.IMG.'+index).style.display = 'none';
      tests the data in the field and if it's null, will set the display of that field to 'none'. The only changes you'll need to make are to the List name (mine is LISTIMAGES) in 1 place and to the field name (mine is SheetImageThumb) in 2 places.

      When rendered, the ID of each image tag in the List is


      index is the zero based row number of the List... available in the event.


      • #4
        Re: list control - how do I only show image if one saved in record?

        Hey Larry - I like your suggestion and it would be preferred to not have a default image as the image upload will only be used rarely.
        Hey David - thanks for popping in. I like your thinking and started to do something similar.
        var e = {listElement:photo}; = 'none';

        The trouble is that for some reason it's not detecting that the photo field is null.
        Various methods have been tried such as'',>0,'', String('' and all of them are unable to perform.
        This is a test comp with our message. It's connected to a table:
        CREATE TABLE `messageboard` (
        `id` int(11) NOT NULL AUTO_INCREMENT,
        `fk_company_id` varchar(40) DEFAULT NULL,
        `lu_created_by` varchar(100) DEFAULT NULL,
        `date_created` datetime DEFAULT NULL,
        `message` varchar(500) DEFAULT NULL,
        `photo` longblob,
        `voiceattach` longtext,
        PRIMARY KEY (`id`)

        I really don't know what to try next! Any suggestions?

        Thank you muchly.



        • #5
          Re: list control - how do I only show image if one saved in record?

          Um, I'm not sure if it's politically/programatically correct but the way I've got around it is
          if (<100) {
          //set control to hidden

          It seems the ones with pictures are coming back at 96, the ones with pictures are much bigger.


          • #6
            Re: list control - how do I only show image if one saved in record?

            This is where having a test case is so vital... so thanks for that... excellent. If you turn Pagination off in your List control, then the value will be null.

            So... if you really need pagination... then you have 2 choices...

            1. Compare to the known "empty" value of a paginated row. Which is...

            On my system, this is what a null blob value looks like when the List is paginated. It'll be interesting to find out if you're seeing the same value.

            Or... you could take a chance and figure that any image is going to be larger than say 200 bytes. Even the smallest image... a thumbnail is usually a few K in length.
            The length of a null, paginated, blob in a List row is 96.

            if( < 200){
            should be true for a row with no photo.



            • #7
              Re: list control - how do I only show image if one saved in record?

              *pleased* Aaahhh! David, I hadn't thought of that.
              Yes, mine returns the exact same "empty" value of a paginated row. "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP4//8/AwAI/AL+eMSysAAAAABJRU5ErkJggg=="

              Great - thank you. That clarifies where I was heading and solves our problem.
              Thank you David.


              • #8
                Re: list control - how do I only show image if one saved in record?

                You'd already solved it. It was an interesting puzzle... I had to find out why and where the difference was.