Delete button gives me error

Question

My delete button does not work after putting endless efforts and thought to post here.When i click on Delete button, its just rerendering and not deleting after trying with actionSupport.

It gives me an error of QueryExcpetion

public class PagingTasksController1{

public List<Task> Tasks;


public Task del;
public Task taskDel;
public Integer CountTotalRecords{get;set;}
public String QueryString {get;set;}
public Integer OffsetSize = 0;
private Integer QueryLimit =3 ;
public List<Task> lstTasks {get;set;}
public String searchText {get;set;}
public String rowIndex {get;set;}
public Date mydate;
public Integer totalCount {get;set;}
public string sortField = 'Subject';  // default sort column
private string sApplySOQL = '';
 public List<Task> delattendeeList {get;set;}

public List<Task> delAttendees {get; set;}

public PagingTasksController1(ApexPages.StandardController controller) {

 taskDel= (Task)controller.getRecord();
 Tasks = [Select id,Subject,Status,ActivityDate from Task where OwnerId =: taskDel.Id];
// this.Tasks=Tasks[0];
 totalCount = Tasks.size();

 delattendeeList = new List<Task>();
 delattendees = new List<Task>();
  }


  // the current sort direction. defaults to ascending
   public String sortDir {
    get  { if (sortDir == null) {  sortDir = 'asc'; } return sortDir;  }
    set;
  }

 // the current field to sort by. defaults to role name
  public String getsortField() {
    return sortField;
}

// the current field to sort by.
 public void setsortField(string value) {
    sortField = value;
 }

// toggles the sorting of query from asc<-->desc
public void toggleSort() {
    // simply toggle the direction
    sortDir = sortDir.equals('asc') ? 'desc' : 'asc';

    integer iIndex = sApplySOQL.indexOf('Order By');
    if (iIndex > -1){
      sApplySOQL = sApplySOQL.substringBefore('Order By');
      sApplySOQL = sApplySOQL + ' Order By ' + sortField + ' ' + sortDir +  ' limit ' + QueryLimit + ' offset ' + OffsetSize;
    }
    tasks = Database.query(sApplySOQL );
}

 public PagingTasksController1 (){
    //CountTotalRecords= [select count() from Task];
    //String qStr2= '7/23/2014';

 }

 public List<Task> getTasks(){
    if(tasks == null){
        tasks = new List<Task>();
    }
    return tasks;
}

   public void findTasks(){
    String qStr2 = 'Select count() from Task where Subject like \'%'+searchText+'%\' OR Status like \'%'+searchText+'%\'';
    CountTotalRecords = Database.countQuery(qStr2);
    queryTasks();
 }

public void  queryTasks(){

    String qStr2= searchText;
    Set<Id> ownerIds = new Set<Id>();
    String strnormal = '';
    try{
         mydate = date.parse(qStr2);
    }catch(Exception e)
    { }

    String strDate = '';
    if(mydate != null) {
     // strnormal = String.valueOf(mydate );
      String[] qstr3 = String.valueOf(mydate).split(' ',2); 
      strDate = ' ActivityDate =  '+ qstr3[0] + ' ';
    }else{

       strDate  =  'Subject like \'%'+searchText +'%\' OR Status like \'%' +searchText+ '%\' Order By '  + sortField;
    }

    if (ownerIds != null && ownerIds.size() > 0){

      String qStr = 'Select OwnerId,Subject,Status,ActivityDate from Task where '+strDate+' limit ' + QueryLimit + ' offset ' + OffsetSize +' and OwnerId in :ownerIds';
      System.debug(qStr); 
      tasks = Database.query(qStr);         
    }

       //String qStr ='Select OwnerId,Subject,Status,ActivityDate from Task where \''+strDate +'\' limit ' + QueryLimit + ' offset ' + OffsetSize;
      // String qStr = 'Select OwnerId,Subject,Status,ActivityDate from Task where '+strDate+' limit ' + QueryLimit + ' offset ' + OffsetSize;


        //  String qStr = 'Select OwnerId,Subject,Status,Priority from Task where Subject like \'%'+searchText+'%\' OR Status like \'%'+searchText+ '%\' Order By ' + sortField;

   //tasks.sort();

     }

   public Boolean getDisablePrevious(){
    if(OffsetSize>0){
        return false;
    }
    else return true;
}

 public Boolean getDisableNext() {
    if (OffsetSize + QueryLimit < countTotalRecords){
        return false;
    }
    else return true;
}

  public PageReference Next() {
    OffsetSize += QueryLimit;
    queryTasks();
    return null;
}

  public PageReference Previous() {
    OffsetSize -= QueryLimit;
    queryTasks();
    return null;
   }

  public PageReference save() {
    update tasks;
    return ApexPages.CurrentPage();
   }

  public void deleteRow(){

     rowIndex = String.valueOf(ApexPages.currentPage().getParameters().get('rowIndex'));
     System.debug('rowIndex ------------'+rowIndex );
     if(rowIndex!=null)
     {
     Task check=[Select id from Task where id=: rowIndex];
     System.debug('row to be deleted ' + check);
     delete check;
     Tasks=[Select Subject,Status,ActivityDate,OwnerId from Task ];
     update Tasks;
       }
     }
   }

VF Page:

      <apex:pageBlockTable value="{!Tasks}" var="tsk" id="pgTable">

     <apex:column headerValue="Action" >
       <apex:commandButton value="Delete" action="{!deleteRow}" reRender="pgTable">
       <apex:param name="rowIndex" value="{!tsk.id}"/>
      </apex:commandButton>             
    </apex:column>


         <!-- <apex:column headerValue="Action" >
        <apex:outputLink value="{!URLFOR($Action.Task.Delete, .id,['retURL'='/apex/New_Test_task_Assignment'])}"> Delete</apex:outputLink>
       </apex:column>  -->

    <apex:column headerValue="OwnerId">
        <apex:outputField value="{!tsk.OwnerId}"/>
    </apex:column>

Answer 1

This is the conventional way to get the apex:param value set on the controller:

<apex:param name="rowIndex" value="{!tsk.id}" assignTo="{!rowIndex}" />

and then all that deleteRow needs to do is to use the ID value (rowIndex ought to be renamed taskId) for the delete and then remove that item from the list of Tasks (or call queryTasks to build the list over again without the deleted Task):

public void deleteRow(){
    delete new Task(Id = rowIndex);
    for (Integer i = 0; i < Tasks.size(); i++) {
        if (Tasks[i].Id == rowIndex) {
            Tasks.remove(i);
            break;
        }
    }
}