Hi,  I am a bit stuck trying to figure out how to properly use the assign to attribute in the param component.

I am trying to display a list of categories (using command link component) .  Based on the category the user selects in the list , I want to filter out the services and display the filtered list below on the same page.

Here is the controller:

public with sharing class wrapperClassController {


public String category {get; set;}


public pagereference viewST(){
return NULL;
}

//This query displays my categories
public List<Service_Categories__c> getCategories(){
return [SELECT Name FROM Service_Categories__c WHERE Service_Name__c = 'NULL'];

}

public List<aServiceTask> servicetaskList {get; set;}

// This query displays my services - however nothing is returned since I beleive my category variable is not being assigned properly throughout the process .
public List<aServiceTask> getServiceTasks() {
    if(servicetaskList == null) {
    servicetaskList = new List<aServiceTask>();
    for(Service_Categories__c a: [select Id, Name, Service_Name__c from Service_Categories__c where Name = :category AND Service_Name__c <>'NULL']) {
    
        servicetaskList.add(new aServiceTask(a));
        }
        }
        return servicetaskList;
       
        }
  

}

Here is the Page:

<apex:page controller="wrapperClassController">
  
  <apex:form >
       <apex:pageBlock >
          <apex:pageBlockSection title="Work Categories">
                 
                  <apex:dataList value="{!Categories}" var="c" id="table" type="none" >
                      <apex:commandLink value="{!c.Name}" action="{!ViewST}" >
                          <apex:param value="{!c.Name}" assignTo="{!category}"/>
                      </apex:commandlink>   
                  </apex:dataList>
                  
         </apex:pageBlockSection>
          
          <apex:pageBlockSection title="Service Tasks">
        
              <apex:commandButton value="Process Selected" action="{!processSelected}" rerender="table"/>
                   <apex:outputText value="{!category}"/>
                      <apex:pageBlockTable value="{!servicetasks}" var="a" id="table">
                          <apex:column >
                              <apex:inputCheckbox value="{!a.selected}"/>
                          </apex:column>
                              <apex:column value="{!a.ST.Service_Name__c}" /> 
                      </apex:pageBlockTable> 
             </apex:pageBlockSection>
        </apex:pageBlock> 
    </apex:form> 
</apex:page>

Thank you in advance!