自定义属性类型的模型绑定器

Question

在ASP.NET Core项目中,我有以下操作:

public async Task<IActionResult> Get(ProductModel model) {
}

public class ProductModel {
  public Filter<Double> Price { get; set; }
}    

我有一个Filter基类和一个RangeFilter,如下所示:

public class Filter<T> { }

public class RangeFilter<T> : Filter<T> { 
  public abstract Boolean TryParse(String value, out Filter<T> filter);  
}

我将String("[3.34;18.75]")传递给Action as Price.

我需要创建一个ModelBinder我使用该TryParse方法的地方,尝试将其String转换RangeFilter<Double>为定义ProductModel.Price属性.

如果TryParse失败,例如,返回false则ProductModel.Price属性变为null.

如何才能做到这一点？

Answer 1

如果您愿意将解析方法移动到静态类中,这将变得更加可行.

分析器

public static class RangeFilterParse
{
    public static Filter<T> Parse<T>(string value)
    {
        // parse the stuff!
        return new RangeFilter<T>();
    }
}

public abstract class Filter<T> { }

public class RangeFilter<T> : Filter<T> { }

模型

public class ProductModel
{
    [ModelBinder(BinderType = typeof(RangeModelBinder))]
    public Filter<double> Price { get; set; }
}

活页夹

public class RangeModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        try
        {
            var input = bindingContext.ValueProvider.GetValue(bindingContext.ModelName).ToString();
            var inputType = bindingContext.ModelType.GetTypeInfo().GenericTypeArguments[0];

            // invoke generic method with proper type
            var method = typeof(RangeFilterParse).GetMethod(nameof(RangeFilterParse.Parse), BindingFlags.Static);
            var generic = method.MakeGenericMethod(inputType);
            var result = generic.Invoke(this, new object[] { input });

            bindingContext.Result = ModelBindingResult.Success(result);
            return Task.CompletedTask;
        }
        catch(Exception) // or catch a more specific error related to parsing
        {
            bindingContext.Result = ModelBindingResult.Success(null);
            return Task.CompletedTask;
        }
    }
}