iot/projects/Infrastructure/Extensions/ViewDataDictionaryExtensions.cs

using System;
using System.Linq.Expressions;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;

namespace Infrastructure.Extensions
{
    public static class ViewDataDictionaryExtensions
    {
        public static void Add(this ViewDataDictionary viewData, object name, object value, bool condition = true)
        {
            if (viewData is null)
            {
                throw new ArgumentNullException(nameof(viewData));
            }
            if (name is null)
            {
                throw new ArgumentNullException(nameof(name));
            }
            if (value is null)
            {
                throw new ArgumentNullException(nameof(value));
            }
            if (condition)
            {
                viewData[name.ToString()] = value;
            }
        }

        public static object Get(this ViewDataDictionary viewData, object name)
        {
            if (viewData is null)
            {
                throw new ArgumentNullException(nameof(viewData));
            }
            if (name is null)
            {
                throw new ArgumentNullException(nameof(name));
            }
            return viewData[name.ToString()];
        }

        public static void SelectList<TResult>(this ViewDataDictionary viewData, Expression<Func<object, TResult>> expression, Func<SelectList> getSelectListFunc, bool value = true)
        {
            if (viewData is null)
            {
                throw new ArgumentNullException(nameof(viewData));
            }
            if (expression is null)
            {
                throw new ArgumentNullException(nameof(expression));
            }
            if (getSelectListFunc is null)
            {
                throw new ArgumentNullException(nameof(getSelectListFunc));
            }
            if (value)
            {
                var name = (expression.Body as MemberExpression).Member.Name + "SelectList";
                viewData[name] = getSelectListFunc();
            }
        }

        public static void MultiSelectList<TResult>(this ViewDataDictionary viewData, Expression<Func<object, TResult>> expression, Func<MultiSelectList> getSelectListFunc, bool value = true)
        {
            if (viewData is null)
            {
                throw new ArgumentNullException(nameof(viewData));
            }
            if (expression is null)
            {
                throw new ArgumentNullException(nameof(expression));
            }
            if (getSelectListFunc is null)
            {
                throw new ArgumentNullException(nameof(getSelectListFunc));
            }
            if (value)
            {
                var name = (expression.Body as MemberExpression).Member.Name + "SelectList";
                if (!viewData.ContainsKey(name))
                {
                    viewData[name] = getSelectListFunc();
                }
            }
        }
    }
}