本地化ASP.NET core模型绑定错误消息

默认错误消息：

MissingBindRequiredValueAccessor    A value for the '{0}' property was not provided.
MissingKeyOrValueAccessor           A value is required.
ValueMustNotBeNullAccessor          The value '{0}' is invalid.
AttemptedValueIsInvalidAccessor     The value '{0}' is not valid for {1}.
UnknownValueIsInvalidAccessor       The supplied value is invalid for {0}.
ValueIsInvalidAccessor              The value '{0}' is invalid.
ValueMustBeANumberAccessor          The field {0} must be a number.

MissingRequestBodyRequiredValueAccessor       A non-empty request body is required.
NonPropertyAttemptedValueIsInvalidAccessor    The value '{0}' is not valid.
NonPropertyUnknownValueIsInvalidAccessor      The supplied value is invalid.
NonPropertyValueMustBeANumberAccessor         The field must be a number.

若要本地化ASP.NET Core 模型绑定错误消息，请按照下列步骤操作：

1. 创建资源文件 - 在解决方案的Resources文件夹下创建资源文件，并将文件命名为ModelBindingMessages.resx。名称可以是其他任何名称，但我们将使用它来创建本地化程序。

2. 添加资源键 - 打开资源文件并添加要用于本地化错误消息的键和值。我使用了键和值

3. 配置选项 - 在ConfigureServices方法中，添加时Mvc，配置其选项以设置以下内容的消息访问者ModelBindingMessageProvider

4.     services.AddMvc(options =>
                {
                    IStringLocalizerFactory F = services.BuildServiceProvider().
                    GetService<IStringLocalizerFactory>();
                    IStringLocalizer L = F.Create("ModelBindingMessages",
                        "AspNetCoreLocalizationSample");
                    options.ModelBindingMessageProvider.
                    SetValueIsInvalidAccessor((x) => L["The value '{0}' is invalid."]);
                    options.ModelBindingMessageProvider.SetValueMustBeANumberAccessor(
                        (x) =>L["The field {0} must be a number."]);
                    options.ModelBindingMessageProvider.SetMissingBindRequiredValueAccessor(
                        (x) => L["A value for the '{0}' property was not provided.", x]);
                    options.ModelBindingMessageProvider.SetAttemptedValueIsInvalidAccessor(
                        (x, y) => L["The value '{0}' is not valid for {1}.", x, y]);
                    options.ModelBindingMessageProvider.SetMissingKeyOrValueAccessor(
                        () => L["A value is required."]);
                    options.ModelBindingMessageProvider.SetUnknownValueIsInvalidAccessor(
                        (x) => L["The supplied value is invalid for {0}.", x]);
                    options.ModelBindingMessageProvider.SetValueMustNotBeNullAccessor(
                        (x) => L["Null value is invalid.", x]);
                }).AddDataAnnotationsLocalization()
        .AddViewLocalization();
        services.Configure<RequestLocalizationOptions>(options =>
        {
            var supportedCultures = new[]{new CultureInfo("en"), new CultureInfo("zh-cn")};
            options.DefaultRequestCulture = new RequestCulture("en", "en");
            options.SupportedCultures = supportedCultures;
            options.SupportedUICultures = supportedCultures;
        });

5. 还要在Configure方法开头添加此代码：

    var supportedCultures = new[] { new CultureInfo("en"), new CultureInfo("zh-CN") };
    app.UseRequestLocalization(new RequestLocalizationOptions()
    {
        DefaultRequestCulture = new RequestCulture(new CultureInfo("en")),
        SupportedCultures = supportedCultures,
        SupportedUICultures = supportedCultures
    });

6. 关于属性DisplayAttribute 

   通过查看源码 在 Microsoft.AspNetCore.Mvc.DataAnnotations.Internal.DataAnnotationsMetadataProvider中有IDisplayMetadataProvider的实现
   主要是判断DisplayName不为空和ResourceType为空的时候使用IStringLocalizerFactory 
   代码片段如下：

       var dataTypeAttribute = attributes.OfType<DataTypeAttribute>().
    if (displayFormatAttribute == null && dataTypeAttribute != null)
                {
                    displayFormatAttribute = dataTypeAttribute.DisplayFormat;
                }
                var displayMetadata = context.DisplayMetadata;
   
                // ConvertEmptyStringToNull
                if (displayFormatAttribute != null)
                {
                    displayMetadata.ConvertEmptyStringToNull = displayFormatAttribute.
                        ConvertEmptyStringToNull;
                }
                // DataTypeName
                if (dataTypeAttribute == null)
                {
                    if (displayFormatAttribute != null && !displayFormatAttribute.HtmlEncode)
                    {
                        displayMetadata.DataTypeName = DataType.Html.ToString();
                    }
                }
                else
                {
                    displayMetadata.DataTypeName = dataTypeAttribute.GetDataTypeName();
                }
   
                var containerType = context.Key.ContainerType ?? context.Key.ModelType;
                IStringLocalizer localizer = null;
                if (_stringLocalizerFactory != null && _localizationOptions.DataAnnotationLocalizerProvider != null)
                {
                    localizer = _localizationOptions.DataAnnotationLocalizerProvider(containerType, _stringLocalizerFactory);
                }
   
                // Description
                if (displayAttribute != null)
                {
                    if (localizer != null &&
                        !string.IsNullOrEmpty(displayAttribute.Description) &&
                        displayAttribute.ResourceType == null)
                    {
                        displayMetadata.Description = () => localizer[displayAttribute.Description];
                    }
                    else
                    {
                        displayMetadata.Description = () => displayAttribute.GetDescription();
                    }
                }
   
                // DisplayFormatString
                if (displayFormatAttribute != null)
                {
                    displayMetadata.DisplayFormatString = displayFormatAttribute.DataFormatString;
                }
   
                // DisplayName
                // DisplayAttribute has precedence over DisplayNameAttribute.
                if (displayAttribute?.GetName() == null)
                {
                    if (displayNameAttribute != null)
                    {
                        if (localizer != null &&
                            !string.IsNullOrEmpty(displayNameAttribute.DisplayName))
                        {
                            displayMetadata.DisplayName = () => localizer[displayNameAttribute.DisplayName];
                        }
                        else
                        {
                            displayMetadata.DisplayName = () => displayNameAttribute.DisplayName;
                        }
                    }
                }
                else
                {
                    if (localizer != null &&
                        !string.IsNullOrEmpty(displayAttribute.Name) &&
                        displayAttribute.ResourceType == null)
                    {
                        displayMetadata.DisplayName = () => localizer[displayAttribute.Name];
                    }
                    else
                    {
                        displayMetadata.DisplayName = () => displayAttribute.GetName();
                    }
                }
   
                // EditFormatString
                if (displayFormatAttribute != null && displayFormatAttribute.ApplyFormatInEditMode)
                {
                    displayMetadata.EditFormatString = displayFormatAttribute.DataFormatString;
                }
   
                // IsEnum et cetera
                var underlyingType = Nullable.GetUnderlyingType(context.Key.ModelType) ?? context.Key.ModelType;
                var underlyingTypeInfo = underlyingType.GetTypeInfo();
   
                if (underlyingTypeInfo.IsEnum)
                {
                    // IsEnum
                    displayMetadata.IsEnum = true;
   
                    // IsFlagsEnum
                    displayMetadata.IsFlagsEnum = underlyingTypeInfo.IsDefined(typeof(FlagsAttribute), inherit: false);
   
                    // EnumDisplayNamesAndValues and EnumNamesAndValues
                    //
                    // Order EnumDisplayNamesAndValues by DisplayAttribute.Order, then by the order of Enum.GetNames().
                    // That method orders by absolute value, then its behavior is undefined (but hopefully stable).
                    // Add to EnumNamesAndValues in same order but Dictionary does not guarantee order will be preserved.
   
                    var groupedDisplayNamesAndValues = new List<KeyValuePair<EnumGroupAndName, string>>();
                    var namesAndValues = new Dictionary<string, string>();
   
                    IStringLocalizer enumLocalizer = null;
                    if (_localizationOptions.AllowDataAnnotationsLocalizationForEnumDisplayAttributes)
                    {
                        if (_stringLocalizerFactory != null && _localizationOptions.DataAnnotationLocalizerProvider != null)
                        {
                            enumLocalizer = _localizationOptions.DataAnnotationLocalizerProvider(underlyingType, _stringLocalizerFactory);
                        }
                    }
                    else
                    {
                        enumLocalizer = _stringLocalizerFactory?.Create(underlyingType);
                    }
   
                    var enumFields = Enum.GetNames(underlyingType)
                        .Select(name => underlyingType.GetField(name))
                        .OrderBy(field => field.GetCustomAttribute<DisplayAttribute>(inherit: false)?.GetOrder() ?? );
   
                    foreach (var field in enumFields)
                    {
                        var groupName = GetDisplayGroup(field);
                        var value = ((Enum)field.GetValue(obj: null)).ToString("d");
   
                        groupedDisplayNamesAndValues.Add(new KeyValuePair<EnumGroupAndName, string>(
                            new EnumGroupAndName(
                                groupName,
                                () => GetDisplayName(field, enumLocalizer)),
                            value));
                        namesAndValues.Add(field.Name, value);
                    }
   
                    displayMetadata.EnumGroupedDisplayNamesAndValues = groupedDisplayNamesAndValues;
                    displayMetadata.EnumNamesAndValues = namesAndValues;
                }
   
                // HasNonDefaultEditFormat
                if (!string.IsNullOrEmpty(displayFormatAttribute?.DataFormatString) &&
                    displayFormatAttribute?.ApplyFormatInEditMode == true)
                {
                    // Have a non-empty EditFormatString based on [DisplayFormat] from our cache.
                    if (dataTypeAttribute == null)
                    {
                        // Attributes include no [DataType]; [DisplayFormat] was applied directly.
                        displayMetadata.HasNonDefaultEditFormat = true;
                    }
                    else if (dataTypeAttribute.DisplayFormat != displayFormatAttribute)
                    {
                        // Attributes include separate [DataType] and [DisplayFormat]; [DisplayFormat] provided override.
                        displayMetadata.HasNonDefaultEditFormat = true;
                    }
                    else if (dataTypeAttribute.GetType() != typeof(DataTypeAttribute))
                    {
                        // Attributes include [DisplayFormat] copied from [DataType] and [DataType] was of a subclass.
                        // Assume the [DataType] constructor used the protected DisplayFormat setter to override its
                        // default.  That is derived [DataType] provided override.
                        displayMetadata.HasNonDefaultEditFormat = true;
                    }
                }
   
                // HideSurroundingHtml
                if (hiddenInputAttribute != null)
                {
                    displayMetadata.HideSurroundingHtml = !hiddenInputAttribute.DisplayValue;
                }
   
                // HtmlEncode
                if (displayFormatAttribute != null)
                {
                    displayMetadata.HtmlEncode = displayFormatAttribute.HtmlEncode;
                }
   
                // NullDisplayText
                if (displayFormatAttribute != null)
                {
                    displayMetadata.NullDisplayText = displayFormatAttribute.NullDisplayText;
                }
   
                // Order
                if (displayAttribute?.GetOrder() != null)
                {
                    displayMetadata.Order = displayAttribute.GetOrder().Value;
                }
   
                // Placeholder
                if (displayAttribute != null)
                {
                    if (localizer != null &&
                        !string.IsNullOrEmpty(displayAttribute.Prompt) &&
                        displayAttribute.ResourceType == null)
                    {
                        displayMetadata.Placeholder = () => localizer[displayAttribute.Prompt];
                    }
                    else
                    {
                        displayMetadata.Placeholder = () => displayAttribute.GetPrompt();
                    }
                }

7.