Asp.net MVC 如何对所有用户输入的字符串字段做Trim处理

经常需要对用户输入的数据在插入数据库或者判断之前做Trim处理，针对每个ViewModel的字段各自做处理是我们一般的想法。最近调查发现其实也可以一次性实现的。

MVC4.6中实现方式

1，实现IModelBinder接口,创建自定义ModelBinder。

public class TrimModelBinder : IModelBinder
    {
        public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
        {
            var valueResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
            string attemptedValue = valueResult?.AttemptedValue;
 
            return string.IsNullOrWhiteSpace(attemptedValue) ? attemptedValue : attemptedValue.Trim();
        }
    }

2，添加ModelBinder到MVC的绑定库。

protected void Application_Start()
        {
            //System.Web.Mvc.ModelBinders.Binders.DefaultBinder = new ModelBinders.TrimModelBinder();
            System.Web.Mvc.ModelBinders.Binders.Add(typeof(string), new ModelBinders.TrimModelBinder());
 
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
        }

3，确认一下效果

将密码后面的空格做Trim处理，绑定到ViewModel的时候变成1了：

Asp.net core 1.1 MVC中实现方式

1,自定义ModelBinder并继承ComplexTypeModelBinder

public class TrimModelBinder : ComplexTypeModelBinder
    {
        public TrimModelBinder(IDictionary propertyBinders) : base(propertyBinders) { }
 
        protected override void SetProperty(ModelBindingContext bindingContext, string modelName, ModelMetadata propertyMetadata, ModelBindingResult result)
        {
            var value = result.Model as string;
 
            result= string.IsNullOrWhiteSpace(value) ? result : ModelBindingResult.Success(value.Trim());
 
            base.SetProperty(bindingContext, modelName, propertyMetadata, result);
        }
    }

2,为ModelBinder添加自定义Provider

public class TrimModelBinderProvider : IModelBinderProvider
    {
        public IModelBinder GetBinder(ModelBinderProviderContext context)
        {
            if (context.Metadata.IsComplexType && !context.Metadata.IsCollectionType)
            {
                var propertyBinders = new Dictionary();
                for (int i = 0; i < context.Metadata.Properties.Count; i++)
                {
                    var property = context.Metadata.Properties[i];
                    propertyBinders.Add(property, context.CreateBinder(property));
                }
                return new TrimModelBinder(propertyBinders);
            }
            return null;
        }
    }

3,将Provider添加到绑定管理库

services.AddMvc().AddMvcOptions(s =>
            {
                s.ModelBinderProviders[s.ModelBinderProviders.TakeWhile(p => !(p is ComplexTypeModelBinderProvider)).Count()] = new TrimModelBinderProvider();
            });

4,确认一下效果