Error: Compile Error: Invalid bind expression type of SOBJECT:Purchase_Order_Details__c does not match domain of foreign key at line 19 column 77

Question

I just started programming in apex, so I will appreciate your help in this case. This class should allow me to get the bundle_Items from bundle object where Bundle__c =(Here is the result of the 'values', which returning the correct Ids, I already tested it). I don't know if I am doing something wrong in the second query, or there might be another approach for the IN: values.

"Error: Compile Error: Invalid bind expression type of SOBJECT:Purchase_Order_Details__c does not match domain of foreign key at line 19 column 79"

Thank you so much in advance!

public class  PO_Vendor_Controller_BundleItems {

    public ApexPages.StandardController std2;
    public List<o_Bundle__c> PODetails2 {get; set;}  
    Public List<Purchase_Order_Details__c> values {get;set;}    

    public PO_Vendor_Controller_BundleItems (ApexPages.StandardController stdCtrl2){
        std2=stdCtrl2; 
        List<Purchase_Order_Details__c> values = [SELECT ProductId__c 
                                                  FROM Purchase_Order_Details__c 
                                                  WHERE PO_ID__c =:std2.getId()]; 
        String[] contractIDs = new string[values.size()]; 

        for (integer i=0; i<values.size(); i++){
             contractIDs[i] = values[i].ProductId__c;
        }
        PODetails2 = [SELECT Bundle_Item__c 
                      FROM o_Bundle__c 
                      WHERE Bundle__c IN:contractIDs ]; 
    }//END init(ApexPages.StandardController stdCtrl2)

}//END PO_Vendor_Controller_BundleItems 

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Update - above Constructor updated

Answer 1

In where clause you have used field 'PO_ID__c'. Make sure that this field is lookup or master-detail field and this field looks up to the SObject mentioned in standardController attribute on VF page.