update opportunity having error

Question

Can anyone please look into this and help me out

Update failed. First exception on row 0; first error: MISSING_ARGUMENT, Id not specified in an update call: []

here is my code :

public Class SelectProductController{

public string Product2Id{get;set;}
Public String OppName{get;set;}
public Opportunity opp{get;set;}
public OpportunityLineItem oli{get;set;}
public Integer prodCount = 0;
public String OppId{get;set;}

public PricebookEntry pdata{get;set;}
public String oppgetname{get;set;}

public String unitprice{get;set;}

public productWrapper[] productList {
get{
    if(productList == null){
        productList = New ProductWrapper[]{};

        for(Product2 p : [select Id, Name, Manufacturer__c,Description from Product2 where IsActive= true order by Manufacturer__c asc ]){
            productList.add(New productWrapper(p,Product2Id));
        }
    }

    return productList;
}
set;
}

public SelectProductController(ApexPages.StandardController Controller){        
    Product2Id = ApexPages.currentPage().getParameters().get('Product2Id');

    opp = new Opportunity();
    OppId = Apexpages.currentPage().getParameters().get('Id');
    opp.LID__LinkedIn_Company_Id__c = Apexpages.currentPage().getParameters().get('oppLID');
    //opp.IsPrivate = Boolean.ValueOf(Apexpages.currentPage().getParameters().get('oppIsPrivate'));
    opp.Name = Apexpages.currentPage().getParameters().get('oppName');
    opp.Accountid = Apexpages.currentPage().getParameters().get('oppAccountid');
    opp.CloseDate = date.parse(Apexpages.currentPage().getParameters().get('oppCloseDate'));
    opp.PrimaryTechnologyArchitect__c = Apexpages.currentPage().getParameters().get('oppPrimaryTech');
    opp.StageName = Apexpages.currentPage().getParameters().get('oppStageName');

    opp.Probability = Decimal.valueOf(Apexpages.currentPage().getParameters().get('oppProbability'));
    opp.Type = Apexpages.currentPage().getParameters().get('oppType');
    opp.WinLoss__c = Apexpages.currentPage().getParameters().get('oppWinLoss__c');
    opp.LeadSource = Apexpages.currentPage().getParameters().get('oppLeadSource');
    opp.Assessment__c = Apexpages.currentPage().getParameters().get('oppAssessment__c');

    opp.Budget__c = Apexpages.currentPage().getParameters().get('oppBudget');
    opp.ContractNumber__c = Apexpages.currentPage().getParameters().get('oppContractNumber');
    opp.Competition__c = Apexpages.currentPage().getParameters().get('oppCompetition');
    opp.Competition2__c = Apexpages.currentPage().getParameters().get('oppCompetition2');
    opp.Competition3__c = Apexpages.currentPage().getParameters().get('oppCompetition3');
    opp.SOW_Nbr__c = Apexpages.currentPage().getParameters().get('oppSOW');
    opp.BIG_Sow_Number__c = Apexpages.currentPage().getParameters().get('oppSowNumber');


    oli = new OpportunityLineItem();
}

public Pagereference save(){

     unitprice = Apexpages.currentPage().getParameters().get('unitprice');

     Product2 tbu = New Product2();


    for(productWrapper p : productlist){

        if(p.isSelected == True){
        prodCount ++;
        }
    }
    if(OppId == Null){
        if(prodCount > 0){
            Insert opp;
        }else{
            apexPages.addmessage(new apexpages.message(apexpages.severity.Error, 'Please select atleast one product.'));
            return new Pagereference('/apex/OppvsProductnew');
        }
    }else{
        update opp;
    }

    for(productWrapper p : productlist){

        if(p.isSelected == True){



            pdata = [select Id from PricebookEntry where Product2Id =: p.prod.id];

                tbu = p.prod;
                oli = new OpportunityLineItem();
                oli.PriceBookEntryId = pdata.id;
                oli.OpportunityId = opp.Id;    
                oli.Quantity = 1;
                //oli.TotalPrice = 100;
                oli.UnitPrice = p.price;
                oli.Description = p.Description;
                insert oli;
        }
    }
    return new Pagereference('/'+Opp.Id);

}


public class productWrapper{
    public Product2 prod {get;set;}
    public boolean isSelected {get;set;}
    public integer price{get;set;}
    public String Description{get;set;}

    public productWrapper(Product2 prod, Id Product2Id){
        this.prod = prod;
        isSelected = prod.Id == Product2Id; 
    }
}
}

Answer 1

You never actually set the Id on the record, you just store it in a separate property. Instead of:

oppId = Apexpages.currentPage().getParameters().get('Id');

Use:

opp.Id = Apexpages.currentPage().getParameters().get('Id');

Just remove the oppId variable from your page entirely and replace it everywhere with opp.Id.

---

You should also get in the habit of never putting DML in a for loop. Right now you have a loop where every iteration calls insert oli;. It is dead simple to move this logic out of the loop, and inexcusable to consume governor limits so wastefully. The basic idea is always:

List<OpportunityLineItem> lineItems = new List<OpportunityLineItem>();
for (...)
{
    lineItems.add(new OpportunityLineItem(...));
}
insert lineItems;

Also worth noting that SObject construction is much faster with key=value pairs:

opp = new Opportunity(
    Id = ApexPages.currentPage().getParameters.get('Id'),
    Name = Apexpages.currentPage().getParameters().get('oppName')
    // etc
);

Answer 2

In your constructor method, you have the following line:

OppId = Apexpages.currentPage().getParameters().get('Id');

The remainder of your lines are used to define the fields in

opp = new Opportunity();

As a consequence, you're not defining opp.Id. That's the source of your issue. You need to assign the value of OppId to opp.Id.