.NET Core 6 MVC：如何让表单值绑定不受当前区域文化影响？

方法1：自定义属性级模型绑定器 #

直接创建针对特定属性的绑定逻辑，强制使用不变文化解析数值：

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

        var valueResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (valueResult == ValueProviderResult.None)
            return Task.CompletedTask;

        bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueResult);
        var rawValue = valueResult.FirstValue;

        if (string.IsNullOrEmpty(rawValue))
            return Task.CompletedTask;

        try
        {
            var parsedValue = double.Parse(rawValue, CultureInfo.InvariantCulture);
            bindingContext.Result = ModelBindingResult.Success(parsedValue);
        }
        catch (FormatException)
        {
            bindingContext.ModelState.TryAddModelError(bindingContext.ModelName, $"值 {rawValue} 无法转换为有效数字");
        }

        return Task.CompletedTask;
    }
}

然后在模型的目标属性上标记使用该绑定器：

public class OrderFormModel
{
    [ModelBinder(BinderType = typeof(InvariantDoubleModelBinder))]
    public decimal ProductPrice { get; set; }
}

方法2：自定义特性+批量绑定处理 #

如果需要给多个属性统一设置解析规则，可以用自定义特性配合绑定提供程序：

1. 创建标记特性：

[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public class UseInvariantCultureAttribute : Attribute
{
}

2. 实现通用绑定器：

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

        var valueResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (valueResult == ValueProviderResult.None)
            return Task.CompletedTask;

        bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueResult);
        var rawValue = valueResult.FirstValue;

        if (string.IsNullOrEmpty(rawValue))
            return Task.CompletedTask;

        try
        {
            object parsedValue;
            var targetType = bindingContext.ModelType;
            
            if (targetType == typeof(double))
                parsedValue = double.Parse(rawValue, CultureInfo.InvariantCulture);
            else if (targetType == typeof(decimal))
                parsedValue = decimal.Parse(rawValue, CultureInfo.InvariantCulture);
            else if (targetType == typeof(float))
                parsedValue = float.Parse(rawValue, CultureInfo.InvariantCulture);
            else
            {
                bindingContext.ModelState.TryAddModelError(bindingContext.ModelName, $"不支持的数值类型 {targetType.Name}");
                return Task.CompletedTask;
            }

            bindingContext.Result = ModelBindingResult.Success(parsedValue);
        }
        catch (FormatException)
        {
            bindingContext.ModelState.TryAddModelError(bindingContext.ModelName, $"值 {rawValue} 格式错误");
        }

        return Task.CompletedTask;
    }
}

3. 注册绑定提供程序：

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

        if (context.Metadata.PropertyAttributes.Any(a => a is UseInvariantCultureAttribute))
        {
            return new BinderTypeModelBinder(typeof(InvariantCultureModelBinder));
        }

        return null;
    }
}

4. 在Program.cs中添加绑定器注册：

builder.Services.AddControllersWithViews(options =>
{
    options.ModelBinderProviders.Insert(0, new InvariantCultureModelBinderProvider());
});

5. 给模型属性添加标记：

public class OrderFormModel
{
    [UseInvariantCulture]
    public decimal ProductPrice { get; set; }

    [UseInvariantCulture]
    public double ProductWeight { get; set; }
}

方法3：手动解析指定参数（适合简单场景） #

放弃自动模型绑定，直接从请求中获取原始值手动解析：

[HttpPost]
public IActionResult SubmitOrder()
{
    var rawPrice = Request.Form["ProductPrice"].ToString();
    if (!decimal.TryParse(rawPrice, CultureInfo.InvariantCulture, out var productPrice))
    {
        ModelState.AddModelError("ProductPrice", "价格格式不正确");
        return View();
    }

    // 后续业务逻辑
    return RedirectToAction("OrderSuccess");
}

内容的提问来源于stack exchange，提问作者user2981411