public class attachController{
public case objcase{get;set;}
public Attachment myAttachment{get;set;}
public string fileName{get;set;}
public Blob fileBody{get;set;}

RecordType recordId = [SELECT Id FROM RecordType WHERE DeveloperName = 'Product_Case'];
Id recId = (recordId != null) ? recordId.Id : null;

Group queueId = [select Id from Group where Type = 'Queue' AND DeveloperNAME = 'Product_Support_Case_Queue' LIMIT 1];
Id ownerId = (queueId != null) ? queueId.Id : null;

//string recId = Schema.SObjectType.Case.getRecordTypeInfosByName().get('Product Case').getRecordTypeId();

public attachController(Apexpages.standardcontroller controller)
{
    objcase = (Case)controller.getRecord();
    myAttachment = new Attachment();
}
public PageReference submit(){
  List<Contact> contacts = [SELECT Id, Email FROM Contact];

    Contact con = [SELECT Id, Email FROM Contact];
    String conId = [SELECT Id, Email FROM Contact WHERE Email := con].Id;

    if (fileName != null){
        objcase.RecordTypeId = recId;
        objcase.ownerId = ownerId;
        objcase.contactID = conId;
        insert objcase;

        myAttachment = new Attachment();
        Integer i=0;
        myAttachment .clear();
        myAttachment.Body = fileBody;
        myAttachment.Name = fileName ;
        myAttachment.ParentId = objcase.id;
        insert myAttachment;
    } else {
        objcase.RecordTypeId = recId;
        objcase.ownerId = ownerId;
        objcase.contactID = conId;
        insert objcase;

    }
    pagereference pr = Page.thankYouForSubmittingYourProductCase;
    pr.setRedirect(true);
    return pr;
}}