Update not working for Visual Force Page fields

Question

I am writing a class to update a record with data from visual force page if it exists in contact, if it does not it will insert a row.I am using Update and Insert statements for this purpose.Looks like the Id of current page not retrieved for update operation. I am using this to update the record. ApexPages.currentPage().getParameters().get('Id') I am using getrecord() to insert a row I am using Try Catch to perform Update and Insert. It always performs Insert.

I put Insert code in Catch because it is giving 'No rows in list to assign to SObject' error for SELECT statement .Let me know if you need code for the page.

Thank you for the help.

Code for Apex Class

 public class thankyoupageredirectext {


 public contact con{get;set;}                    
 public contact con1{get;set;}     

 string Other_In_Kind_Donation__c,Scoop_value,description_value;
  string Clothing_In_Kind_Donation_value;
  string contact_url;
 string Food_In_Kind_Donation_value;         

 public thankyoupageredirectext (ApexPages.StandardController stdController)    {   

 con1 = (contact)stdController.getRecord();     

  }     

 public PageReference save(){  

     try
  {
     con =  [SELECT Id,firstname, Title,lastname,description,The_Scoop__c,email,Other_In_Kind_Donation__c,Clothing_In_Kind_Donation__c,Food_In_Kind_Donation__c FROM contact  WHERE Id = :ApexPages.currentPage().getParameters().get('Id')];
   update con;     
   retun null;
}
  catch (exception e)
{

  this.con = con1;
  insert con;
  return  null;

  }                      


  }

}

Code for Visual Force Page

 <apex:page standardController="contact"    extensions="thankyoupageredirectext"   sidebar="false" showHeader="false" >

<style type="text/css">

 .myClass {
  color:Black;
  font-size: 30px;          
  text-align:center;
}

</style>

<apex:form >

<apex:pageBlock >
<apex:pageBlockSection columns="1" >
  <apex:outputLabel value="In-Kind Donation" styleClass="myClass"/>

     <apex:inputField value="{! contact.firstname}"/> 
     <apex:inputField value="{! contact.lastname}"/>
     <apex:inputField value="{! contact.GW_Volunteers__Volunteer_Organization__c}"/>
     <apex:inputField value="{! contact.Title}"/>
     <apex:inputField value="{! contact.email}"/>
     <apex:inputField value="{! contact.phone}"/>      
     <apex:inputField value="{!contact.MailingStreet}"/>
     <apex:inputField value="{!contact.MailingCity}"/>
     <apex:inputField value="{!contact.MailingState}"/>
     <apex:inputField value="{!contact.MailingPostalCode}"/>
     <apex:inputField value="{!contact.MailingCountry}"/>             
     <apex:inputField value="{! contact.Clothing_In_Kind_Donation__c}"/>
     <apex:inputField value="{! contact.Food_In_Kind_Donation__c}"/>
     <apex:inputField value="{! contact.The_Scoop__c}" required="true"/>

 </apex:pageBlockSection>       
<apex:pageBlockButtons location="bottom" >          
<apex:commandbutton value="Submit" action="{!save}"/>
</apex:pageBlockButtons>     
</apex:pageBlock> 
</apex:form>  
</apex:page>

Answer 1

Better gather the data during page load and assign in the controller Constructor.

And finally perform upsert operation (which is combination of insert and update) in Save method. Refer Upsert Records in documentation.

Controller

public contact con{get;set;}
public thankyoupageredirectext (ApexPages.StandardController stdController)    
{
    con = (contact)stdController.getRecord();     
}     



 public PageReference save()
 { 
     try
    {   upsert con;     
        return null;
    }
     catch (exception ex)
    {
        ApexPages.Message msg = new ApexPages.Message(ApexPages.Severity.Error, ex.getMessage());
        ApexPages.addMessage(msg);
        return null;
    }
}

Change the <apex:inputField/> value attribute from Contact to con (which is Contact instance)

Visualforce

<apex:form>
     <apex:inputField value="{! con.firstname}"/> 
     <apex:inputField value="{! con.lastname}"/>
     <!--  add other attributes -->

</apex:form>

Updated based on comments

Put id explicitly in the parameter

PageReference pg = new PageReference(ApexPages.CurrentPage);
pg.getParameters().put('id', controller.getId());
pg.setRedirect(true);
return pg;