Hi guys,

I need your help. I have this error and i can't find any solution. im stuck for a few days now...thanks (heres the code)

Error Message:    System.QueryException: List has no rows for assignment to SObject  ---- Class.POController.<init>: line 31, column 1

Code:

public class POController {
public String orderLineItems { get; set; }

public String getPO_Line_Item() {
return null;
}

public class MissingAccountException extends Exception {}
public class NoLineItemsException extends Exception {}


public Account account {get; private set;}
public Opportunity opportunity {get; private set;}
public Purchase_Order__c order {get; private set;}
public OpportunityLineItem oppLineItem {get; private set;}
public PO_Line_Item__c[] poLineItems {get; private set;}
public PO_Line_Item__c poLineItem {get; private set;}
public List<PO_Line_Item__c> lineItems= new List<PO_Line_Item__c>();
private integer itemCount=0;

private PriceBookEntry pbEntry;

public POController() {

Boolean ShowPartner=false;
Id id = ApexPages.currentPage().getParameters().get('id');
//Id accountId=ApexPages.currentPage().getParameters().get('aId');
Id opportunityId = ApexPages.currentPage().getParameters().get('oId');

opportunity = (opportunityId == null) ? new Opportunity() :[SELECT name, accountID, CloseDate, Description, StageName, Pricebook2Id FROM Opportunity WHERE id = pportunityId];

if (opportunity.AccountId != null){
account =new Account();
account= [SELECT name, accountnumber, billingstreet, BillingCity, BillingState, BillingPostalCode, BillingCountry,ShippingStreet, ShippingCity, ShippingState, ShippingPostalCode, ShippingCountry, phone, fax FROM account WHERE id = pportunity.AccountId] ;
}else {
throw new MissingAccountException('Cannot create an order from this opportunity: Please assign an account to the opportunity.');
}

order = (id == null) ? new Purchase_Order__c() :
[SELECT Purchase_Order__c.Name FROM Purchase_Order__c WHERE id = :id];

//Pre-populate Opportunity and account information
order.Status_Code__c='New';


//Create a new PO_Line_Item__c and populate a row for each POLineItem that exists

integer i = 0;
poLineItems = new PO_Line_Item__c[0];
for(OpportunityLineItem opp: [SELECT Id, SortOrder, PricebookEntryId, Description, Quantity, ListPrice, UnitPrice, TotalPrice, ServiceDate FROM OpportunityLineItem WHERE Opportunityid = pportunityId])
{

string pbeID = opp.PricebookEntryId;
pbEntry = (pbeId == null) ? new PriceBookEntry() :
[Select Id, Name, Pricebook2Id, Product2Id, ProductCode from PricebookEntry where Id=beID];


poLineItem = new PO_Line_Item__c();
poLineItem.Purchase_Order__c=order.Id;
poLineItem.Product__c = pbEntry.Product2Id;
poLineItem.Name = pbEntry.Name;
poLineItem.Unit_Price__c = opp.ListPrice;
poLineItems.add(poLineItem);
i++;
}
itemCount=i;
if (itemCount == 0) {
throw new NoLineItemsException('Unable to create PO: Products must be added to Sales Order before creating a PO.');
}
System.Debug('Finished Page Load');

}

//Returns the user back to the Sales Order page this was launched from
public PageReference cancel(){
return (new ApexPages.StandardController(Opportunity)).view();
}
//saves PO and child PO
public PageReference save() {
System.Debug('Running Save Method');

try
{
insert order;
System.Debug(order.id);
for(PO_Line_Item__c li: poLineItems)
{
li.Purchase_Order__c=order.id;
}
insert poLineItems;
//If the Opportunity Stage is not 'Closed Won' then update it
if (Opportunity.StageName != 'Closed Won'){
Opportunity.StageName='Closed Won';
update Opportunity;
}
}catch(System.DMLException e)
{
ApexPages.addMessages(e);
return null;
}

// After Save, navigate to the default view page:
return (new ApexPages.StandardController(order)).view();
}

public PageReference loadHelpPage(){
PageReference pg = new PageReference('/apex/CreatePOHelp');
return pg;
}

}