Hi

I have a requirement in which i have to make a dynamic picklist , such that picklist values should change as per the value selected by user in other field.

I have two fields one is look up and another is picklist , Whatever user selects in look up field   i have to make a query depending on that input and show picklist values.

My code

VF

<apex:page standardController="Account" extensions="Accountextension" >
<apex:form >
<apex:pageBlock id="thePageBlock" >
<apex:pageBlockSection >
<apex:inputField id="product" value="{!Account.Product__c}">
<apex:actionSupport event="onchange" rerender="thePageBlock"
status="status"/>
</apex:inputField>
<apex:pageBlockSectionItem >
<apex:outputLabel value="Products available" for="Productsavailable"></apex:outputLabel>
<apex:selectList id="Productsavailable" size="1" title="Products available">
<apex:selectOptions value="{!mgrs}"></apex:selectOptions>
</apex:selectList>
</apex:pageBlockSectionItem>
</apex:pageBlockSection>
</apex:pageBlock>
</apex:form>
</apex:page>

Controller

public class Accountextension {
    private final Account acc;
    String product;
        
    public String getProduct() {
    return acc.Product__c ;
    }
   
    public void setProduct() {
   product=acc.Product__c;

    }
           
        public Accountextension(ApexPages.StandardController stdController) {
        this.acc = (Account)stdController.getRecord();
    }
            //builds a picklist
          public List<selectOption> getMgrs() {
           System.debug ('**********************LOGIN1*********************'+acc.Product__c);

        List<selectOption> options = new List<selectOption>(); //new list for holding all of the picklist options
        options.add(new selectOption('', '- None -')); //add the first option of '- None -' in case the user doesn't want to select a value or in case no values are returned from query below
        for (Product2 prod : [Select id ,Name From Product2 where id = :product]) { //query for products
                   options.add(new selectOption(prod.id ,String.valueOf(prod.Name))); //for all records found - add them to the picklist options
        }
        return options; //return the picklist options
    }

}

My problem is  in the query (highlighted in bold)  it is not  recognising the id in query , though i am getting the correct id  .

Debug log:

USER_DEBUG|[20]|DEBUG|**********************LOGIN1*********************01t90000000pbhEAAQ
22:51:50.054 (54454000)|SYSTEM_METHOD_EXIT|[20]|System.debug(ANY)
22:51:50.054 (54482000)|SYSTEM_METHOD_ENTRY|[23]|LIST.add(ANY)
22:51:50.054 (54513000)|SYSTEM_METHOD_EXIT|[23]|LIST.add(ANY)
22:51:50.054 (54530000)|SOQL_EXECUTE_BEGIN|[24]|Aggregations:0|Select id ,Name From Product2 where id= :product
22:51:50.057 (57518000)|SOQL_EXECUTE_END|[24]|Rows:0

Please  help me with this problem