Page Block Table With Dynamic Columns In Salesforce

This is something extensively used, but every time I need to look for some easy code.

So here is the solution (apologies as I've not covered the negative cases in code, and I hope you all are smart enough to take care of that). Requirement is to build the dynamic page block table with dynamic columns, but this is not it. It should be so dynamic that user can select the object and it's fields by himself and nothing should be hard-coded. So first of all I've provided a picklist with all objects (not all objects... why? Take a look at it Please Remove The System Objects From My sObject List)

Visualforce Page Code:

<apex:page controller="DynamicTableController">
<apex:pageBlock >
    <apex:form >
        <apex:actionFunction name="ObjectFileds" action="{!ObjectFields}"/>
        
        <apex:commandButton  value="Show Table" action="{!ShowTable}"/>
        
        <apex:pageBlockSection >
            <apex:pageBlockSectionItem >
                <apex:outputLabel value="Select Object"/>
                <apex:selectList multiselect="false" size="1" value="{!SelectedObject}" onchange="ObjectFileds();">
                    <apex:selectOption itemLabel="--None--" itemValue="--None--"/>
                    <apex:selectoptions value="{!supportedObject}" />
                </apex:selectlist>
            </apex:pageBlockSectionItem>
            
            <apex:pageBlockSectionItem >
                <apex:outputLabel value="Select Field"/>
                <apex:selectList multiselect="true" size="5" value="{!SelectedFields}">
                    <apex:selectOption itemLabel="--None--" itemValue="--None--"/>
                    <apex:selectoptions value="{!fieldLableAPI}" />
                </apex:selectlist>
            </apex:pageBlockSectionItem>
            
            <apex:pageBlockTable rendered="{!IF(ObjectList.size > 0 , true , false)}" value="{!ObjectList}" var="rec">
                <apex:column value="{!rec.Id}" rendered="{!IF(SelectedFields.size == 0 , true, false)}"/>
                <apex:repeat value="{!SelectedFields}" var="FieldLable">
                    <apex:column value="{!rec[FieldLable]}" rendered="{!IF(FieldLable != '--None--' , true, false)}"/>
                </apex:repeat>
            </apex:pageBlockTable>
            
            <apex:outputPanel rendered="{!IF(ObjectList.size < 1 , true , false)}">
                <apex:pageMessage severity="ERROR" summary="No records to display"/>
            </apex:outputPanel>
            
        </apex:pageBlockSection>
        
    </apex:form>
</apex:pageBlock>
</apex:page>

Apex Code (Class):

public class DynamicTableController
{
    //List displayed on UI
    public List<selectoption> supportedObject {get; set;}
    
    //Selected Object
    public String SelectedObject {get; set;}
    
    //Global describe
    Map<String, Schema.SObjectType> gd = Schema.getGlobalDescribe();
    Set<String> objectKeys = gd.keySet();
    
    //Field Select List
    public List<SelectOption> fieldLableAPI {get; set;}
    
    //Selected fields to be displayed in table
    public List<String> SelectedFields {get; set;}
    
    //List to maintain dynamic query result
    public List<sObject> ObjectList {get; set;}
    
    
    //Constructor
    public DynamicTableController()
    {
        //Initialize
        supportedObject = new List<selectoption>() ;
        SelectedObject = '' ;
        fieldLableAPI = new List<SelectOption>() ;
        SelectedFields = new List<String>() ;
        ObjectList = new List<sObject>() ;
        
        //Get only reference to objects
        for(Schema.SObjectType item : ProcessInstance.TargetObjectId.getDescribe().getReferenceTo())
        {
            //Excluding custom setting objects
            if(!item.getDescribe().CustomSetting)
            {
                //Adding to list
                supportedObject.add(new SelectOption(item.getDescribe().getLocalName().toLowerCase() , item.getDescribe().getLabel() ));
            }
        }
        
    }
    
    //Get fields of selected object
    public void ObjectFields()
    {
        if(SelectedObject != '--None--')
        {
            //Creating sObject for dynamic selected object
            Schema.SObjectType systemObjectType = gd.get(SelectedObject);
            //Fetching field results
            Schema.DescribeSObjectResult r = systemObjectType.getDescribe();
                
            Map<String, Schema.SObjectField> M = r.fields.getMap();
            //Creating picklist of fields
            for(Schema.SObjectField fieldAPI : M.values())
            {
                fieldLableAPI.add(new SelectOption(fieldAPI.getDescribe().getName() , fieldAPI.getDescribe().getLabel())) ;
            }
        }
    }
    
    public void ShowTable()
    {
        //Creating dynamic query with selected field
        String myQuery = 'Select Id ' ;
        
        for(String field : SelectedFields)
        {
            if(field.toLowerCase() != 'id' && field.toLowerCase() != '--none--')
            myQuery += ','+ field + ' ' ;
        }
        
        //Limit is 100 for now you can change it according to need
        myQuery += ' from ' + SelectedObject + ' LIMIT 100' ;
        
        //Executing the query and fetching results
        ObjectList = Database.query(myQuery) ;
    }
}

Once user selects any object from the first picklist, filed picklist will be populated with all the field labels related to that object. Note, it's a multi-select picklist so user can select multiple fields. Once fields are selected and "Show Table" is clicked, page block table will display the field values (selected in field picklist) of all records (limit is 100 right now, you can change it according to your need).

There are some extra checks that needs to be implemented in code like "isQueryable" etc..