JW/Framework/Bowin.Common/FormDataBinder.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.UI;
using System.Reflection;
using System.ComponentModel;
using Bowin.Common.Utility;

namespace Bowin.Common
{
    public class FormDataBinder
    {
        private static Dictionary<Type, PropertyInfo> controlValueProperties = new Dictionary<Type, PropertyInfo>();
        public event EventHandler<DataBindingEventArgs> DataItemBinding;
        public event EventHandler<DataBindingEventArgs> DataItemBound;

        public static IEnumerable<BindingMapping> BuildBindingMappings(Type entityType, Control container, string suffix = "")
        {
            Guard.ArgumentNotNullOrEmpty(entityType, "entityType");
            Guard.ArgumentNotNullOrEmpty(container, "container");
            suffix = suffix??string.Empty;

            return (from property in DataPropertyAttribute.GetDataProperties(entityType)
                    let control = container.FindControl(string.Format("{1}{0}", suffix, property.Name))
                    let controlValueProperty = GetControlValueProperty(control)
                    where null != control
                    select new BindingMapping(control, controlValueProperty, property)).ToArray();
        }

        public void BindData(object entity, Control container, string suffix = "")
        {
            Guard.ArgumentNotNullOrEmpty(entity, "entity");
            Guard.ArgumentNotNullOrEmpty(container, "container");
            var bingingMappings = BuildBindingMappings(entity.GetType(), container, suffix);
            this.BindData(entity, bingingMappings);
        }

        public void BindData( object entity,IEnumerable<BindingMapping> bindingMappings)
        {
            Guard.ArgumentNotNullOrEmpty(bindingMappings, "bindingMappings");
            Guard.ArgumentNotNullOrEmpty(entity, "entity");
            this.OnBindData(bindingMappings, entity);
        }

        protected virtual void OnBindData(IEnumerable<BindingMapping> bindingMappings, object entity)
        {
            foreach (var bindingMapping in bindingMappings)
            {
                object value = bindingMapping.DataSourceProperty.GetValue(entity, null);               

                if (null != this.DataItemBinding)
                {
                    this.DataItemBinding(this, new DataBindingEventArgs(bindingMapping, value));
                }
                if (!bindingMapping.AutomaticBind)
                {
                    continue;
                }

                if (!string.IsNullOrEmpty(bindingMapping.FormatString))
                {
                    value = Format(value, bindingMapping.FormatString);
                }
                
                value = ChangeType(value, bindingMapping.ControlValueProperty.PropertyType);
                if (null != value)
                {
                    bindingMapping.ControlValueProperty.SetValue(bindingMapping.Control, value, null);
                    if (null != this.DataItemBound)
                    {
                        this.DataItemBound(this, new DataBindingEventArgs(bindingMapping, value));
                    }
                }
            }
        }

        private static object Format(object value, string formatString)
        {
            if (null == value)
            {
                return string.Empty;
            }
            IFormattable formattable = value as IFormattable;
            if (null != formattable)
            {
                return formattable.ToString(formatString, null);
            }

            if (value.GetType().IsGenericType && value.GetType().GetGenericTypeDefinition() == typeof(Nullable<>))
            { 
                object underlyingValue = Convert.ChangeType(value, Nullable.GetUnderlyingType(value.GetType()));
                return Format(underlyingValue, formatString);
            }
            return value;            
        }

        private static PropertyInfo GetControlValueProperty(Control control)
        {
            if (null == control)
            {
                return null;
            }
            Type entityType = control.GetType();
            if (controlValueProperties.ContainsKey(entityType))
            {
                return controlValueProperties[entityType];
            }
            lock (typeof(FormDataBinder))
            {
                if (controlValueProperties.ContainsKey(entityType))
                {
                    return controlValueProperties[entityType];
                }
                var controlValuePropertyAttribute = (ControlValuePropertyAttribute)entityType.GetCustomAttributes(typeof(ControlValuePropertyAttribute), true)[0];
                var property = entityType.GetProperty(controlValuePropertyAttribute.Name);
                controlValueProperties[entityType] = property;
                return property;
            }
        }

        private static object ChangeType(object value, Type type)
        {
            if (null == value)
            {
                if (type == typeof(string))
                { 
                    return string.Empty;
                }
                if (type == typeof(bool))
                {
                    return false;
                }
                return null;
            }
            if (type.IsGenericType)
            {
                if (type.GetGenericTypeDefinition() == typeof(Nullable<>))
                {
                    return new NullableConverter(type).ConvertTo(value, type);
                }
                throw new InvalidCastException(string.Format("Invalid cast from \"{0}\" to \"{1}\".",
                    value.GetType().FullName, type.FullName));
            }
            else
            {                
                return Convert.ChangeType(value, type);
            }
        }
    }
}