Working With Multiselect Picklists

Working with Picklists essentially is rewarded since it limits the options of the user and standards what is valid as a value for a field in the system. As good as they are however they bring their own complexity with them.

This is especially true when you are working with multi-select Picklists. Mostly Visualforce’s inputField is used to view multi-select Picklists as Salesforce team is working on it to be more effective and error-free.

In this article we will see how to use the multi-select Picklists.

First off, let’s see how we can load values into our Picklist and view it on our Visualforce page.
Let’s say I have a custom multi-select Picklist field on my User object to define sales regions my users operate on.

The picklist has values such as:

• North America
• Latin America
• Europe
• Asia
• Middle East
• Africa
  

and so on

In my controller class I add the following property:

public class multiselectPicklist {
 private User salesRegions;

 public multiselectPicklist()
 {
    salesRegions = new User();
 }
 public User getSalesRegions() {
      return salesRegions;
 }
 public void setSalesRegions(User Value) {
      salesRegions = Value;
 }
}

As you can see it is enough to create a new User object and later on use the picklist field to show the values on your page. Unfortunately there is no other way through which you would more control over what values are shown on your multi-select control. May be in future Salesforce will supply a Component for multi-select operations.

Please note that I have created a setter property as well that receives a User object. This setter allows us to later on read the selected values by user.

Now that we have our controller ready we can program our page to view our multi-select picklist.
in this example what I am trying to achieve is that to allow the user choose as many regions as he/she wants and them filter the Users of the system and view only those who are assigned to those regions.

<apex:page controller="multiselectPicklist" tabStyle="User" sideBar="false">
<apex:form >
   <apex:sectionHeader title="Users by Region Report"></apex:sectionHeader>
 
   <apex:pageBlock id="pageBlock" title="Search Filter">
    <apex:pageMessages ></apex:pageMessages>
    <apex:pageBlockSection title="Filters" columns="2" collapsible="true">
       <apex:inputField id="salesRegions" value="{!salesRegions.Sales_Regions__c}" ></apex:inputField>
    </apex:pageBlockSection>
   </apex:pageBlock>
   <apex:pageBlock id="searchResults" title="Results">
     <apex:pageBlockButtons >
        <apex:commandButton value="Run Report" action="{!runReport}" status="status" rerender="searchResults"></apex:commandButton>
     </apex:pageBlockButtons>
     <apex:pageMessages ></apex:pageMessages>
     <apex:pageBlockTable value="{!users}" var="u" rendered="{!NOT(ISNULL(users))}" rules="cols">
        <apex:column value="{!u.UserName}"></apex:column>
        <apex:column value="{!u.IsActive}"/>
     </apex:pageBlockTable>
  </apex:pageBlock>
</apex:form>
</apex:Page>

Something that you should bear in mind is that even though multi-select option suggests that you should be dealing with a list of Strings as a result of user’s interaction with your control on the page all you will receive will just a semicolon separated string. It is your job to separate the values and use then in whatever endeavor you intend to have.



Below on my button action I have demonstrated how you can read the selected values back and use them in your query to get a list of users in those sales regions:

 public PageReference runReport() {

    if (salesRegions.Sales_Regions__c == null || salesRegions.Sales_Regions__c == '') {
      apexPages.addmessage(new ApexPages.message(ApexPages.severity.INFO, 'Please select one or more regions first.'));
      return null;
    }
    // read the values into an array
    string[] regions = salesRegions.Sales_Regions__c.split(';',0);
    if (regions != null && regions.size() > 0)
    {
       //query the database based on the user's selection
       users = [select Username, IsActive, Id from user where Sales_Regions__c in :regions and IsActive = true order by Username];
    }
  
      return null;
  }

 private List<User> users;
 
 public List<User> getUsers()
 {
    return users;
 }
}

Something funny that occurred to me was that I tried to hook the Multi-select Component (inputField) with actionSupport to capture onChange event and load values of another Picklist item on my project which was totally a disappointment! It seems that the Salesforce team has been able to get that one to work yet.