Adding Child Picklist Value to Record

Question

I have a visualforce page to generate a OpportunityLineItem. It is launched from the Opportunity page. I want a picklist for users to enter a custom field Product_Type__c.

The Opportunity is the controller of record on the page.

I have been able to query the schema for the values. How do I assign this to field?

Here is my Controller snippet:

public class AddProduct {

    private ApexPages.StandardController sc;
    public Opportunity record {get; private set;}
    public OpportunityLineItem ELI {get; set;}
    public OpportunityLineItem CusLi {get;set;}
    public Opportunity Op {get; set;}

    public List<SelectOption> getProdSubTypes1(){
        List<SelectOption> options = new List<SelectOption>();
        Schema.DescribeFieldResult fieldResult = OpportunityLineItem.Product_SubType__c.getDescribe(); 
        List<Schema.PicklistEntry> ple = fieldResult.getPicklistValues();
        for( Schema.PicklistEntry f : ple)
       {
          options.add(new SelectOption(f.getLabel(), f.getValue()));
       }       
       return options; 
    }

    public AddProduct(ApexPages.StandardController controller) {
        if (!Test.isRunningTest()) Controller.addFields(new List<String>{'Name', 'PriceBook2Id'});
        record = (Opportunity)controller.getRecord();
        sc= controller;
        ELI = new OpportunityLineItem();
        CusLI = new OpportunityLineItem();
        }


 public PageReference AddEmailProduct (){

        Opportunity TheOpp = (Opportunity)sc.GetRecord();
        ELI.OpportunityId=TheOpp.id;
        ELI.PricebookEntryId=[select id from PricebookEntry where name =: 'Email' 
                            and Pricebook2id=:Theopp.Pricebook2Id].id;

         ELI.Quantity=1;
         ELI.Product_Type__c='Email';
    ELI.Product_SubType__c = ????



        insert ELI;
}

VF Page Snip:

<apex:commandButton action="{!AddEmailProduct}" value="Email" />           
<apex:selectList size="1">
<apex:selectOptions value="{!ProdSubTypes1}"></apex:selectOptions>
</apex:selectList>

Answer 1

You need to bind the value attribute of apex:selectList as below

<apex:selectList value="{ELI.Product_SubType__c}" size="1">
    <apex:selectOptions value="{!ProdSubTypes1}"></apex:selectOptions>
</apex:selectList>

For more examples on usage refer : https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_compref_selectList.htm

Answer 2

This works with a change to the suggested answer. I still query for the picklist values but I added a variable to the class :

public String SubType{get;set;} 

Then on the visualforce page I make the variable the selectlist value:

 <apex:selectList value="{!SubType}" size="1">
    <apex:selectOptions value="{!SubTypeList}">
    </apex:selectoptions>
</apex:selectList>

This passes the value correctly.