Category: CTH

Country Tag Helper–part 5

Now the Country Tag Helper supports .NET Standard 2.0 . This means that support .NET Core 2.0 .

Also, I have made a NuGET package in order to install on every .NET Core 2.0 application with explanations: https://www.nuget.org/packages/CountryTagHelper 

The only trouble here was to add references and make documentation in VS2017 about package ( see https://docs.microsoft.com/en-us/nuget/guides/create-net-standard-packages-vs2017 )

As I said , the source is at GitHub https://github.com/ignatandrei/CountryTagHelper and demo at http://countrytaghelper.apphb.com/

What remains to be done:

localized
add select2 with image flags   

provider / dependency injection for FromIP
readme.md / wiki on github

Country Tag Helper–part 4

 

Now I want to see somewhere in order to prove it Ii s right. I choose https://appharbor.com/ because it is free – and can not beat free for free source.

I made github integration and modify the .csproj file accordingly to https://support.appharbor.com/discussions/problems/90387-is-net-core-supported-yet 

The result is at http://countrytaghelper.apphb.com/ 

Also , I have to modify the code source to get the ip of the user :

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string GetUserIP(ViewContext vc)
        {
            StringValues headerFwd;
            if (ViewContext.HttpContext?.Request?.Headers?.TryGetValue("X-Forwarded-For", out headerFwd) ?? false)
            {
                string rawValues = headerFwd.ToString();
                if (!string.IsNullOrWhiteSpace(rawValues))
                {
                    return rawValues.Split(',')[0];
                }
 
            }
            return ViewContext.HttpContext?.Connection?.RemoteIpAddress?.ToString();
 
        }

where ViewContext is

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[ViewContext]
       public ViewContext ViewContext { get; set; }

Country Tag Helper – part 3

Adding empty item – easy peasy. Just append "<option selected style=’display: none’ value=”></option>";

 

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if (ASPCountryEmpty)
                {
                    string empty = "<option selected style='display: none' value=''></option>";
                    output.Content.AppendHtml(empty);
                }

For getting the IP, I was trying to balance the 2 variants: downloading GeoIP database (https://dev.maxmind.com/geoip/geoip2/geolite2/) or calling http://freegeoip.net/ .

I do call http://freegeoip.net/ – and the next point is to use Dependency Injection … or a provider to do that.

For the moment, the code is:

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private async Task<string> GetCountryCodeFromIP(string ip)
       {
           //ip= "188.25.145.65";
           var url = "http://freegeoip.net/csv/"+ip;
           var request = WebRequest.Create(url);
           request.Method = "GET";
           using (var wr = await request.GetResponseAsync())
           {
               using (var receiveStream = wr.GetResponseStream())
               {
                   using (var reader = new StreamReader(receiveStream, Encoding.UTF8))
                   {
                       string content = reader.ReadToEnd();
                       return content.Split(',')[1];
                   }
                        
               }
                    
           }
 
 
       }

CountryTagHelper–part 2

Finally, I have arrived at functionality. I said that I want something like

<select asp-country="true" asp-country-selected="US" >
   
</select>

 

The functionality is very easy to be added:

The entire class is :

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using Microsoft.AspNetCore.Razor.TagHelpers;
using Microsoft.Extensions.Localization;
using System;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;
 
namespace CTHWeb.Controllers
{
    [HtmlTargetElement("select", Attributes = ASPCountryAttributeName)]
    public class CountryTagHelper:TagHelper
    {
        private const string ASPCountryAttributeName = "asp-country";
        private const string ASPCountrySelectedAttributeName = "asp-country-selected";
 
        [HtmlAttributeName(ASPCountryAttributeName)]
        public bool ASPCountry { get; set; }
 
        [HtmlAttributeName(ASPCountrySelectedAttributeName)]
        public string ASPCountrySelected{ get; set; }
 
        static string[] CountryISO;
        //static PropertyInfo[] properties;
        static CountryTagHelper()
        {
            var t =typeof( ResCTH);
            var properties= t.GetProperties(
                BindingFlags.Public |
                BindingFlags.Static |
                BindingFlags.GetProperty);
            CountryISO = properties
                .Where(it=>it.Name.Length==2)
                .Select(it => it.Name)
                .ToArray();
        }
        public override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
        {
            if (ASPCountry)
            {
                bool existSelected = !string.IsNullOrWhiteSpace(ASPCountrySelected);
                string option = "<option value='{0}' {2}>{1}</option>";
                foreach (var item in CountryISO)
                {
                    string selected = "";
                    string localizedName = ResCTH.ResourceManager.GetString(item);
                    if (existSelected)
                    {
                        bool currentItem = string.Equals(item, ASPCountrySelected, StringComparison.CurrentCultureIgnoreCase);
                        currentItem = currentItem || string.Equals(localizedName, ASPCountrySelected, StringComparison.CurrentCultureIgnoreCase);
                        if (currentItem)
                            selected = "selected";
                    }
                    output.Content.AppendFormat(option, item, localizedName,selected);
                }
            }
            return base.ProcessAsync(context, output);
        }
    }
}

 

The important thing is that it works with other html attributes, like

<select asp-country="true" asp-country-selected="US" disabled=”disabled”>
   
</select>

 

What it remains to be done:

  1. from IP – recognize the country of the visitor from IP
  2. localized – display messages in other language
  3. first item empty – now it selects Andorra
  4. Add select2 with image flags
  5. NuGet package
  6. readme.md / wiki on github
  7. tests

Country tag helper–part 1

 

What I want to do is to create a Country Tag Helper for asp.net core.

Something like

<select asp-country=”true”

and then list all countries in this select. More, it should be localized ( Germany vs Allemagne). That means 1 or more resource files 

 

First I need initial data: The WorldBank API gives us the names http://api.worldbank.org/countries and I have made a project https://github.com/ignatandrei/WorldBankAPi that inspects that API.

To retrieve data in resource format , it is simple:

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var r = new CountriesRepository();
           var arr = r.GetCountries().Result.
               Select(it =>
               $"<data name = \"{it.iso2Code}\" xml:space=\"preserve\" >" +
 
               $"<value>{it.name}</value>" +
               "</data>").ToArray();
           var s = string.Join(Environment.NewLine, arr);
           File.WriteAllText(@"D:\c.txt", s);

 

Then we could copy paste into resources:

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<data name = "AW" xml:space="preserve" ><value>Aruba</value></data>
 <data name = "AF" xml:space="preserve" ><value>Afghanistan</value></data>
 <data name = "AO" xml:space="preserve" ><value>Angola</value></data>
...

 

Now I want to make a list of those names – so I need this code to translate between C# generated code from resource

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public static string AD {
            get {
                return ResourceManager.GetString("AD", resourceCulture);
            }
        }
public static string AE {
            get {
                return ResourceManager.GetString("AE", resourceCulture);
            }
        }
...

 

and a list of names to be put into select.

Reflection to the rescue:

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var t =typeof( ResCTH);
          properties= t.GetProperties(
              BindingFlags.Public |
              BindingFlags.Static |
              BindingFlags.GetProperty);
          CountryISO = properties
              .Where(it=>it.Name.Length==2)
              .Select(it => it.Name)
              .ToArray();

 

The code is on github https://github.com/ignatandrei/CountryTagHelper and I will improve next time.

Andrei Ignat weekly software news(mostly .NET)

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