ASP.NET Core 1 Web API模型绑定数组

Question

你如何建模在ASP.NET Core 1 Web API中使用GET从URI中绑定数组(隐式或显式)？

在ASP.NET Web API pre Core 1中,这有效:

[HttpGet]
public void Method([FromUri] IEnumerable<int> ints) { ... }

你是如何在ASP.NET Web API Core 1(又名ASP.NET 5又名ASP.NET vNext)中做到这一点的？文档什么都没有.

Answer 1

本FromUriAttribute类综合FromRouteAttribute和FromQueryAttribute类.根据路由的配置/发送的请求,您应该能够用其中一个替换您的属性.

但是,有一个垫片可供你FromUriAttribute上课.通过软件包资源管理器安装"Microsoft.AspNet.Mvc.WebApiCompatShim"NuGet软件包,或将其直接添加到project.json文件中:

"dependencies": {
  "Microsoft.AspNet.Mvc.WebApiCompatShim": "6.0.0-rc1-final"
}

虽然它有点旧,但我发现这篇文章在解释一些变化方面做得非常好.

捆绑

如果您要为数组绑定逗号分隔值("/ api/values？ints = 1,2,3"),则需要像以前一样使用自定义绑定器.这是适用于ASP.NET Core 的Mrchief解决方案的改编版本.

public class CommaDelimitedArrayModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext.ModelMetadata.IsEnumerableType)
        {
            var key = bindingContext.ModelName;
            var value = bindingContext.ValueProvider.GetValue(key).ToString();

            if (!string.IsNullOrWhiteSpace(value))
            {
                var elementType = bindingContext.ModelType.GetTypeInfo().GenericTypeArguments[0];
                var converter = TypeDescriptor.GetConverter(elementType);

                var values = value.Split(new[] { "," }, StringSplitOptions.RemoveEmptyEntries)
                    .Select(x => converter.ConvertFromString(x.Trim()))
                    .ToArray();

                var typedValues = Array.CreateInstance(elementType, values.Length);

                values.CopyTo(typedValues, 0);

                bindingContext.Result = ModelBindingResult.Success(typedValues);
            }
            else
            {
                // change this line to null if you prefer nulls to empty arrays 
                bindingContext.Result = ModelBindingResult.Success(Array.CreateInstance(bindingContext.ModelType.GetElementType(), 0));
            }

            return TaskCache.CompletedTask;
        }

        return TaskCache.CompletedTask;
    }
}

您可以指定要用于所有集合的模型绑定器Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services.AddMvc().AddMvcOptions(opts =>
        {
            opts.ModelBinders.Insert(0, new CommaDelimitedArrayModelBinder());
        });
}

或者在API调用中指定一次:

[HttpGet]
public void Method([ModelBinder(BinderType = typeof(CommaDelimitedArrayModelBinder))] IEnumerable<int> ints)

Answer 2

ASP.NET Core 1.1答案

@ WillRay的回答有点过时了.我写了一个'IModelBinder'和'IModelBinderProvider'.第一个可以与[ModelBinder(BinderType = typeof(DelimitedArrayModelBinder))]属性一起使用,而第二个可以用于全局应用模型绑定,如下所示.

.AddMvc(options =>
{
    // Add to global model binders so you don't need to use the [ModelBinder] attribute.
    var arrayModelBinderProvider = options.ModelBinderProviders.OfType<ArrayModelBinderProvider>().First();
    options.ModelBinderProviders.Insert(
        options.ModelBinderProviders.IndexOf(arrayModelBinderProvider),
        new DelimitedArrayModelBinderProvider());
})

public class DelimitedArrayModelBinderProvider : IModelBinderProvider
{
    public IModelBinder GetBinder(ModelBinderProviderContext context)
    {
        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        if (context.Metadata.IsEnumerableType && !context.Metadata.ElementMetadata.IsComplexType)
        {
            return new DelimitedArrayModelBinder();
        }

        return null;
    }
}

public class DelimitedArrayModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
        {
            throw new ArgumentNullException(nameof(bindingContext));
        }

        var modelName = bindingContext.ModelName;
        var valueProviderResult = bindingContext.ValueProvider.GetValue(modelName);
        var values = valueProviderResult
            .ToString()
            .Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
        var elementType = bindingContext.ModelType.GetTypeInfo().GenericTypeArguments[0];

        if (values.Length == 0)
        {
            bindingContext.Result = ModelBindingResult.Success(Array.CreateInstance(elementType, 0));
        }
        else
        {
            var converter = TypeDescriptor.GetConverter(elementType);
            var typedArray = Array.CreateInstance(elementType, values.Length);

            try
            {
                for (int i = 0; i < values.Length; ++i)
                {
                    var value = values[i];
                    var convertedValue = converter.ConvertFromString(value);
                    typedArray.SetValue(convertedValue, i);
                }
            }
            catch (Exception exception)
            {
                bindingContext.ModelState.TryAddModelError(
                    modelName,
                    exception,
                    bindingContext.ModelMetadata);
            }

            bindingContext.Result = ModelBindingResult.Success(typedArray);
        }

        return Task.CompletedTask;
    }
}