Pre populate field value in Sitecore WFFM

In order to pre populate values in Sitecore WFFM, we can create custom action for this. Sample code to pre populate values in Sitecore WFFM

public class SampleCustomAction<T> : RuleAction<T> where T : ConditionalRuleContext
    {
        public override void Apply(T ruleContext)
        {
            Item FieldItem = null;
            if (ruleContext.Control is IResult)
            {
                FieldItem = GetItemFromDatabase(Sitecore.Context.Database.Name, ((IResult)ruleContext.Control).FieldID);
                if (FieldItem != null)
                {
                    string FieldValue = GetFieldValueFromDB(((IResult)ruleContext.Control).ControlName);
                    ((IResult)ruleContext.Control).DefaultValue = FieldValue;
                }
                return;
            }
        }

        public Item GetItemFromDatabase(string database, string FormUri)
        {
            Sitecore.Data.Database db = Sitecore.Configuration.Factory.GetDatabase(database);
            return db.GetItem(FormUri);
        }

        public string GetFieldValueFromDB(string fieldName)
        {
            string FieldValue = string.Empty;
            return FieldValue;
        }
    }