一.前言

　　通过各种姿势搜索都没搜到这方面的,唯一找到一个比较符合的,但是只适合简单类型,而且代码还没贴全,心累。。

然后查看官网和源码之后,发现继承并实现 IModelBinder和IModelBinderProvider 即可。

我这里是WebApi,所以要区分绑定属性[FromBody]、[FromForm]等。不同的绑定方法要实现不同的IModelBinder。

二:正文

　　api主要设计到的就是[FromBody]和[FromQuery],我这里也只实现了这两种,其余的方式没测试过。

 

public class StringTrimModelBinderProvider : IModelBinderProvider    {        private readonly IList
     
       _formatters;        public StringTrimModelBinderProvider(IList
      
        formatters)        {            _formatters = formatters;        }        public IModelBinder GetBinder(ModelBinderProviderContext context)        {            if (context == null)                throw new ArgumentNullException(nameof(context));            if (!context.Metadata.IsComplexType && context.Metadata.ModelType == typeof(string))            {                //简单类型                var loggerFactory = (ILoggerFactory)context.Services.GetService(typeof(ILoggerFactory));                return new SimpleStringTrimModelBinder(context.Metadata.ModelType);            }            else if (context.BindingInfo.BindingSource != null &&                context.BindingInfo.BindingSource.CanAcceptDataFrom(BindingSource.Body))            {                //通过[FromBody]绑定的                return new BodyStringTrimModelBinder(_formatters, context.Services.GetRequiredService
       
        ());            }            //else            //if (context.Metadata.IsComplexType && !context.Metadata.IsCollectionType)            //{            //    //复杂类型            //    var propertyBinders = context.Metadata.Properties            //        .ToDictionary(modelProperty => modelProperty, modelProperty => context.CreateBinder(modelProperty));            //    var loggerFactory = (ILoggerFactory)context.Services.GetService(typeof(ILoggerFactory));            //    return new AComplexTypeModelBinder(propertyBinders);            //}            return null;        }    }
       
      
     

 

 

下面的是实现IModelBinder

 

public class SimpleStringTrimModelBinder : IModelBinder    {        private readonly Type _type;        public SimpleStringTrimModelBinder(Type type)        {            _type = type;        }        public Task BindModelAsync(ModelBindingContext bindingContext)        {            if (bindingContext == null)            {                throw new ArgumentNullException(nameof(bindingContext));            }            var valueProvider = bindingContext.ValueProvider;            var modelName = bindingContext.ModelName;            var valueProviderResult = valueProvider.GetValue(modelName);            if (valueProviderResult == ValueProviderResult.None)            {                return Task.CompletedTask;            }            string value = valueProviderResult.FirstValue.Trim();            //bindingContext.ModelState.SetModelValue(modelName, new ValueProviderResult(value));            //替换原有ValueProvider            bindingContext.ValueProvider = new CompositeValueProvider                {                    new ElementalValueProvider(modelName, value, valueProviderResult.Culture),                    bindingContext.ValueProvider                };            //调用默认系统绑定            SimpleTypeModelBinder simpleTypeModelBinder = new SimpleTypeModelBinder(_type, (ILoggerFactory)bindingContext.HttpContext.RequestServices.GetService(typeof(ILoggerFactory)));            simpleTypeModelBinder.BindModelAsync(bindingContext);            //bindingContext.Result = ModelBindingResult.Success(value);            return Task.CompletedTask;        }    }

 

public class BodyStringTrimModelBinder : IModelBinder    {        private readonly BodyModelBinder bodyModelBinder;        public BodyStringTrimModelBinder(IList
     
       formatters, IHttpRequestStreamReaderFactory readerFactory)        {            bodyModelBinder = new BodyModelBinder(formatters,readerFactory);        }        public Task BindModelAsync(ModelBindingContext bindingContext)        {            if (bindingContext == null)            {                throw new ArgumentNullException(nameof(bindingContext));            }            //调用原始body绑定数据            bodyModelBinder.BindModelAsync(bindingContext);            //判断是否设置了值            if (!bindingContext.Result.IsModelSet)            {                return Task.CompletedTask;            }            //获取绑定对象            var model = bindingContext.Result.Model;            /*通过反射修改值,            也可以实现 IInputFormatter接口里面的ReadAsync方法,自己从Request.Body里面获取数据进行处理,但是那样考虑的比较多也比较复杂,原谅我能力有限。。*/            var stringPropertyInfo = model.GetType().GetProperties().Where(c=>c.PropertyType == typeof(string));            foreach (PropertyInfo property in stringPropertyInfo)            {                string value = property.GetValue(model)?.ToString()?.Trim();                property.SetValue(model, value);            }            //bindingContext.Result = ModelBindingResult.Success(value);            return Task.CompletedTask;        }    }
     

最后,需要将我们自定义的在Startup注册进去,

services.AddMvc(options =>            {                //需要插入到第一条,内置默认是匹配到合适的Provider就不会在向下继续绑定;如果添加到末尾,即不会调用到我们实现的                options.ModelBinderProviders.Insert(0,new StringTrimModelBinderProvider(options.InputFormatters));            })

 

记录成长中的点点滴滴。。