Field not rendering properly on VF page

Question

I have developed page to display..object,itsfields,childobjects,relationships and childobjfields

right now i have a problem with to render the child object fields..when we do change in parent objects... it should render by according to respective child object fields.

Class:

public with sharing class ConfigurationController {

    public Map <String, Schema.SObjectType> schemaMap = Schema.getGlobalDescribe();
    public String selectedObject {get; set;}
    public String selectedField {get; set;}
    public String selectedChildobject {get; set;}
    public String selectedchildField {get; set;}
    public String Relationship {get; set;}

    Public ConfigurationController() {
        selectedObject = 'Account';
        selectedChildobject = 'Account';
    }

    public List<SelectOption> getObjectNames() {
        List<SelectOption> objNames = new List<SelectOption>();
        List<String> entities = new List<String>(schemaMap.keySet());
        entities.sort();
        for (String name : entities) {
            objNames.add(new SelectOption(schemaMap.get(name).getDescribe().getName() , schemaMap.get(name).getDescribe().getLabel() ));
        }
        return objNames;
    }

    public List<SelectOption> getObjectFields() {
        Map<String, Schema.SObjectType> schemaMap = Schema.getGlobalDescribe();
        Schema.SObjectType ObjectSchema = schemaMap.get(selectedObject);
        Map<String, Schema.SObjectField> fieldMap = ObjectSchema.getDescribe().fields.getMap();
        List<SelectOption> fieldNames = new List<SelectOption>();
        for (String fieldName : fieldMap.keySet()) {
            fieldNames.add(new SelectOption(fieldMap.get(fieldName).getDescribe().getLabel(), fieldMap.get(fieldName).getDescribe().getLabel()));
        }
        return fieldNames;
    }

    public List<SelectOption> getRelatedObjects() {
        map<string, string> relatedObjectsMap = new map<string, string>();
        system.debug('selectedObject :' + selectedObject);
        list<Schema.Childrelationship> relatedObjectsList = Schema.getGlobalDescribe().get(selectedObject).getdescribe().getChildRelationships();
        system.debug('relatedObjectsList :' + relatedObjectsList);
        List<SelectOption> ChildobjNames = new List<SelectOption>();
        for (Schema.Childrelationship  relatedObject : relatedObjectsList) {
            if (relatedObject.getChildSObject().getDescribe().isUpdateable()
                    &&
                    relatedObject.getChildSObject().getDescribe().getKeyPrefix() != null
                    &&
                    !relatedObject.getChildSObject().getDescribe().isCustomSetting()
                    &&
                    relatedObject.getChildSObject().getDescribe().isCreateable()
               )
                ChildobjNames.add(new SelectOption(relatedObject.getChildSObject().getDescribe().getName(), relatedObject.getChildSObject().getDescribe().getLabel()));
            system.debug('ChildobjNames :' + ChildobjNames);
        }
        return ChildobjNames;
    }

    public List<SelectOption> getRelationships() {
        map<string, string> relatedObjectsMap = new map<string, string>();
        system.debug('selectedObject :' + selectedObject );
        list<Schema.Childrelationship> relatedObjectsList = Schema.getGlobalDescribe().get(selectedObject).getdescribe().getChildRelationships();
        system.debug('relatedObjectsList :' + relatedObjectsList);
        List<SelectOption> Relationships = new List<SelectOption>();
        for (Schema.Childrelationship  relatedObject : relatedObjectsList) {
            if (relatedObject.getChildSObject().getDescribe().isUpdateable()
                    &&
                    relatedObject.getChildSObject().getDescribe().getKeyPrefix() != null
                    &&
                    !relatedObject.getChildSObject().getDescribe().isCustomSetting()
                    &&
                    relatedObject.getChildSObject().getDescribe().isCreateable()
               )
                if (relatedObject.getRelationshipName() != null) {
                    Relationships.add(new SelectOption(relatedObject.getRelationshipName(), relatedObject.getRelationshipName()));
                }
            system.debug('Relationships :' + Relationships);
        }
        return Relationships;
    }

    public List<SelectOption> getChildObjectFields() {
        Map<String, Schema.SObjectType> schemaMap = Schema.getGlobalDescribe();
        system.debug('selectedChildobject :' + selectedChildobject);
        Schema.SObjectType ObjectSchema = schemaMap.get(selectedChildobject);
        Map<String, Schema.SObjectField> ChildfieldMap = ObjectSchema.getDescribe().fields.getMap();
        List<SelectOption> ChildfieldNames = new List<SelectOption>();
        for (String ChildfieldName : ChildfieldMap.keySet()) {
            ChildfieldNames.add(new SelectOption(ChildfieldMap.get(ChildfieldName).getDescribe().getLabel(), ChildfieldMap.get(ChildfieldName).getDescribe().getLabel()));
        }
        return ChildfieldNames;
    }
}

Vf page:

<apex:page controller="ConfigurationController" sidebar="false"> 
<apex:form > 
  <apex:pageBlock >
      <apex:pageBlockSection columns="2" title="ParentSection">

          <apex:pageBlockSectionItem >
              <apex:outputlabel value="Object:"/> 
                  <apex:actionRegion >      
                       <apex:selectList value="{!selectedObject}" size="1">
                                <apex:selectOptions value="{!ObjectNames}"/>
                                <apex:actionSupport event="onchange" rerender="myFields,childobj,relationship,childfields1"/>
                       </apex:selectList>
                 </apex:actionRegion>                         
          </apex:pageBlockSectionItem>

          <apex:pageBlockSectionItem >
                  <apex:outputlabel value="Fields:"/>   
                  <apex:outputPanel id="myFields">   
                    <apex:actionRegion >  
                       <apex:selectList value="{!selectedField}" size="1">
                            <apex:selectOptions value="{!ObjectFields}"/>
                        </apex:selectList>
                    </apex:actionRegion>      
                 </apex:outputPanel>
          </apex:pageBlockSectionItem>

      </apex:pageBlockSection>

       <apex:pageBlockSection columns="3" title="ChildSection"> 

          <apex:pageBlockSectionItem >
              <apex:outputlabel value="ChildObjects:"/> 
                  <apex:outputPanel id="childobj">   
                  <apex:actionRegion >      
                       <apex:selectList value="{!selectedChildobject}" size="1">
                                <apex:selectOptions value="{!RelatedObjects}"/>  
                                <apex:actionSupport event="onchange" rerender="childfields"/>
                        </apex:selectList>
                 </apex:actionRegion>
                 </apex:outputPanel>                         
          </apex:pageBlockSectionItem>

          <apex:pageBlockSectionItem >
              <apex:outputlabel value="Relationships:"/> 
                 <apex:outputPanel id="relationship">
                 <apex:actionRegion >      
                       <apex:selectList value="{!Relationship}" size="1">
                                <apex:selectOptions value="{!Relationships}"/>
                        </apex:selectList>
                 </apex:actionRegion>
                 </apex:outputPanel>                          
          </apex:pageBlockSectionItem>

          <apex:pageBlockSectionItem >
                  <apex:outputlabel value="Fields:"/>   
                  <apex:outputPanel id="childfields">    
                    <apex:actionRegion >  
                       <apex:selectList value="{!selectedchildField}" size="1">
                            <apex:selectOptions value="{!ChildObjectFields}"/>
                        </apex:selectList>
                    </apex:actionRegion>      
                  </apex:outputPanel>     
          </apex:pageBlockSectionItem>

      </apex:pageBlockSection>
  </apex:pageBlock>
 </apex:form>

Answer 1

The issue is not that it is not re-rendering but actually the way you have written your code, it means it is dependent on the value of

selectedObject

However you are not explicitly updating this when you select a new value in the dropdown for selected object. This happens because you are using the standard setter / getter and have not provided your own implementation. What you need to do is update the setter of

selectedObject

so that it looks something like this

public String selectedObject { get; set { selectedObject = value; selectedChildobject = value; } }

Hope this helps.