Integration of Salesforce.com and AutoCAD WS - Part 4

By Daniel Du

In part 3, I have already list the attachments in visual force page, and add one command link behind each attachment. Now I want to pass parameters to Apex class controllers from visual force page. I need to know which attachment should be opened in AutoCAD WS when user clicks the command link, I am passing the attachment ID as parameter.

<script type="text/javascript"> 
 function openInWS(url){
   window.open(url);
 }
</script>

<apex:column id="colOpenInAcadWS" 
       rendered="{!CONTAINS(item.ContentType, 'application/x-dwg')}">
    <p id="{!count}.openInAcadWS"></p>
    <apex:commandLink action="{!transferToWSStorage}" 
         title="Open In AutoCAD WS"   
         id="btnOpenInAutoCADWs"
         value="Open In AutoCAD WS" 
         styleClass="btn"  style="text-decoration:none"
         oncomplete="openInWS('{!openInAutocadWSUrl}');" >
        <apex:param name="selectedAttachmentId" 
              value="{!item.Id}"/>
    </apex:commandLink>
    <apex:pageBlock id="hiddenBlock" rendered="false">
    </apex:pageBlock>
</apex:column>

Here I assign an action “transferToWSStorage” to command link, it is defined in controller, it will be executed when command link is clicked. Another visual force tag <apex: param> is added to pass parameters.

To avoid query database twice, I store the attachments into a map, so that it can be retrieved by ID without query database again.

Here is the controller code:

public with sharing class                    OpenInAutocadWS_Controller {     public List<Attachment> listAttachment      {get;set;}     public Map<String, Attachment> mapAttachment       {get; set;}     public Case currentCase {get; set;}         public string openInAutocadWSUrl{get;set;}               //constructor       public OpenInAutocadWS_Controller        (ApexPages.StandardController controller) {         //get the controller instance         currentCase = (Case)controller                            .getRecord();                  //initialize the attachments list         listAttachment = new List<Attachment>();                 //get all the case related attachments         listAttachment =            [Select Id, ContentType, Name, Body              from Attachment              where ParentId = :currentCase.Id              and Name like '%DWG'];                 //save into a map for latter use         mapAttachment =               new Map<String, Attachment>();         for(Attachment item : listAttachment ) {            //trim() is important!!!!             //Where the hell blanks comes from?!             //It took me almost two days to debug...             mapAttachment.put(                    String.valueOf(item.Id).trim(),                     item);             System.Debug('ID=' + item.Id                         + 'Name=' + item.name                         + ' is added to map');         }              }             public string selectedAttachmentId     {get; set; }         public void transferToWSStorage()     {             //trim() is important!!!!          //Where the hell blanks comes from?!          //It took me almost two days to debug...         selectedAttachmentId =               ApexPages.currentPage()             .getParameters()             .get('selectedAttachmentId').trim();                 //I have already get the selected attachment ID,         //this is to get the attachement from map by id         Attachment attach =            getAttachmentById(selectedAttachmentId);                 //TO DO: Transfer the attachment to AutoCAS WS         // and get file open url in AutoCAD WS               //TO DO: set openInAutocadWSUrl          //so that it can be opened in AutoCAD WS         openInAutocadWSUrl = ‘https://www.autocadws.com/…’;             }         //get the attachment from map by id     public Attachment getAttachmentById                       (String attachmentId){        //This blocks me almost 2 days,         //just because the trim() issue!         Attachment att = mapAttachment                     .get(attachmentId);         return att;             } }

You probably have known, to access Apex objects from visual force page, we can use {! apexPublicVarible}. For example, I will open the DWG file in AutoCAD WS, after get the file URL I will open it with JavaScript.

An attribute is defined in Apex Class:

public string openInAutocadWSUrl{get;set;}

To get the value from apex class controller and use as parameter of JavaScript:

oncomplete="openInWS('{!openInAutocadWSUrl}');"

Please pay attention to the singe quote in parameter.

I am using an <Apex : param> tag to pass attachment ID to Apex class controller. 

<apex:param name="selectedAttachmentId"
value="{!item.Id}"/>

The value can be retrieved from Apex class by following code:

selectedAttachmentId =
ApexPages.currentPage()
.getParameters()
.get('selectedAttachmentId').trim();

Actually the code is pretty simple, but a very small bug blocked me almost 2 days! As careless as me, I accidentally type a SPACE in value, so the value passed to the controller is not correct, no wander I cannot get the correct item by mapAttachment (attchemendId);

<apex:param name="selectedAttachmentId" 
                    value="[SPACE]{!item.Id}"/>

It is not a big deal, but is very difficult to debug! I will talk about debug in next post.

Stay tuned and have fun!