Tuesday, September 24, 2019

[Code Snippet] Example of using Delegate, Func and Action side by side in C#

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Quick and dirty example of using Delegate, Func and Action
side by side in C# to show how to use function pointer  or callback in C#


Example #1  Delegate and Func side by side

     static int DoubleTheValue(int x)
        {
            return x * 2;
        }

        // delegate type should match the function signature  - DoubleTheValue
        public delegate int functionDelegateType(int x);
     
        static void Method1(functionDelegateType func)
        {
            int doubleValue = func(5);
        }


        static void Method2(Func<int, int> func) // easier syntax
        {
            int doubleValue = func(5);
        }

        static void Main(string[] args)
        {
            Method1(DoubleTheValue);

            Method2(DoubleTheValue);
        }

Example #2  Delegate and Action side by side

static void DisplayOnConsole(int x)
        {
            Console.WriteLine(x.ToString());
        }

        // delegate type should match the function signature  - DisplayOnConsole
        public delegate void functionDelegateType (int x);
        static void Method1(functionDelegateType func)
        {
            func(5);
        }

     
        static void Method2(Action<int> func) // easier syntax
        {
            func(5);
        }

     
        static void Main(string[] args)
        {
            Method1(DisplayOnConsole);
            Method2(DisplayOnConsole);
        }

Reference:
https://social.msdn.microsoft.com/Forums/vstudio/en-US/a1ac99ed-0801-4773-a866-4223d42422cf/how-to-pass-function-as-an-argument-to-another-function-in-c?forum=csharpgeneral

Tuesday, September 3, 2019

[Code snippet] INotifyPropertyChanged in the model and subscribed the PropertyChanged event of the model in ViewModel

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internal class Model:INotifyPropertyChanged
    {
        public Model()
        {
        }

        string _FirstName = "Shahir";
        public string FirstName
        {
            get { return _FirstName; }
            set
            {
                _FirstName = value;
                OnPropertyChanged();
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged([CallerMemberName] string propertyName = "")
        {
            if(PropertyChanged!=null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }


internal class MyViewModel:INotifyPropertyChanged
    {
        private Model myModel;

        public MyViewModel(Model model)
        {
            this.myModel = model;
            myModel.PropertyChanged += myModel_PropertyChanged;
        }


        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged([CallerMemberName] string propertyName = "")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }


        string _FirstName;
        public string MyFirstName
        {
            get { return myModel.FirstName; }
            set
            {
                _FirstName = value;
                OnPropertyChanged();
            }
        }

        private void myModel_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            if (e.PropertyName == "FirstName")
            {
                MyFirstName = myModel.FirstName;
            }
        }
    }

REFERECE - https://www.codeproject.com/Questions/1055820/How-the-Model-changes-could-be-notified-to-ViewMod

Tuesday, August 20, 2019

Code snippet: ArcGIS Runtime 100.x Geodatabase Delta Sync

1 Comment
ESRI namespaces

using Esri.ArcGISRuntime.Tasks.Offline;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Tasks;
using Esri.ArcGISRuntime.Http;



Code snippet

string localGeodatabaseName = @"C:\Data\test.geodatabase";

string deltaGeodatabaseName = @"C:\Deltas\_ags_data{52DwertD40459D02EC197E5EC12C}.geodatabase";

Task<IReadOnlyList<SyncLayerResult>> syncTaskResult = GeodatabaseSyncTask.ImportGeodatabaseDeltaAsync(localGeodatabaseName , deltaGeodatabaseName );

Code snippet: HTTP call to ArcGIS server from ArcGIS Runtime Enviroment 100.x

1 Comment
Required namespaces - 

using System.Net.Http;
using Esri.ArcGISRuntime.Http;

using Newtonsoft.Json; //To parse the response

Code snippet - 

Uri requestUri = new Uri(serviceUrl +"?f=pjson");

//Default HttpClient handler which also handles the ArcGIS server Identity
ArcGISHttpClientHandler handler = new ArcGISHttpClientHandler() 
                                                                  { UseDefaultCredentials = true };

HttpClient client = new HttpClient(handler);

string serverResponseJsonString = await client.GetStringAsync(requestUri);

Console.WriteLine(serverResponseJsonString );  
              

//Convert respones string to JSON Object, optional
ArcGisServerResponse  serverResponseJson = JsonConvert.DeserializeObject<ArcGisServerResponse>(serverResponseJsonString);


Saturday, June 15, 2019

Flavours of .NET implementation

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 OSOpen SourcePurpose
.NET FrameworkWindowsNoUsed for building Windows desktop applications and ASP.NET Web apps running on IIS.
.NET CoreWindows, Linux, macOSYesUsed for building cross-platform console apps and ASP.NET Core Web apps and cloud services.
XamariniOS, Android, macOSYesUsed for building mobile applications for iOS and Android, as well as desktop apps for macOS.
.NET StandardN/AYesUsed for building libraries that can be referenced from all .NET implementations, such as .NET Framework, .NET Core and Xamarin.


Sunday, May 19, 2019

Code Snippet: ESRI JS API 4.11 get Latittude Longitude on mouse hover

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ESRI JS API 4.11 get Latittude Longitude on mouse hover


//print point on mouse hover on map






mapView.on("pointer-move", function(event){
let mapPoint = mapView.toMap({x: event.x, y: event.y});
console.log(mapPoint);
});




//print point on mouse click on map

mapView.on("click", function(event){
let mapPoint = event.mapPoint;
console.log(mapPoint)
});

Both console statement will return the identical object as below which has latitude and longitude

  1. {__accessor__: b}
    1. cache(...)
    2. extent(...)
    3. hasM(...)
    4. hasZ(...)
    5. latitude(...)
    6. longitude(...)
    7. m(...)
    8. spatialReference(...)
    9. type(...)
    10. x(...)
    11. y(...)
    12. z(...)
    13. constructed(...)
    14. destroyed(...)
    15. initialized(...)

Friday, April 12, 2019

Code Snippet : Windows NTLM POST using Node JS

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let ntlm = require('request-ntlm-lite');

let postData = 'user=test';   //anything

let headers = {'Content-Type': 'application/x-www-form-urlencoded'};

let ntlmOptions = {                 
url: 'postUrl',
username: 'username',
password: 'password',
workstation:'',
rejectUnauthorized: false, //disable ssl certificate error
ntlm_domain: 'domain_name',
json: true,
headers:headers
};


ntlm.post(ntlmOptions, postData, function(error, response, body){
console.log(error);
console.log(response);                     
});

Database Configuration to connect with named instance SQL Server with mssql for node.js

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After some frustration, it found that Node JS mssql (5.0.5) doesn't like instance name in config file to make mssql.ConnectionPool(config)-

Works


    dbConfig: {
        "user": "user",
        "password": "pass",
        "server": "myserver",  //  Without instance name 
        "database": "dbname",
        "port":1433,
        "driver": "tedious",
        "options": {
            "instance":"mylocaldevdatabase",
            "trustedConnection": true
          }
        }


Doesn't Work

Thursday, March 28, 2019

ESRI JS API 4.8 makes default call to unsupported API to generate token.

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ESRI Identity Manager, ESRI JS API 4.8 makes default call to unsupported API to generate token.
ID calls to portal/sharing  in stead of portal/sharing/rest/ for token.

Friday, March 22, 2019

Generate ArcGIS Token By URL Request From ArcGIS Portal, Federated Environment , ESRI JS API and Angular snippets

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In my custom angular web application, I had to pull the data from different ArcGIS server environments, say Dev ArcGIS server and Test ArcGIS server environment, some of my items are directly referred from ArcGIS server services and some of them are from Enterprise portal referring the WebMapId and PortalId from both environment (Dev, Test). Servers are in federated environment.

To pull the data from different ArcGIS server environment, user must login in each environment. In addition, user must login to get inside the custom application and Enterprise AD Group was set to authenticate users on the custom web application and ArcGIS server environments. So, there will be 3 login attempts (1 –application itself, 2- Dev server/portal, 3- Test server/portal) to use the application, which doesn’t provide good user experience.

To improve the better application workflow, I decided to reduce the number of logins required in the application and use AD Username and Password captured during application login to generate token for each ArcGIS server environment. Here are some reference snippets to generate token from ArcGIS server and use tokens request parameter in ESRI JS API and Angular.


Step 1: Generate token and store tokens in session 


 devServerLogin(username, password){
     let portalTokenUrl = ....+'/portal/sharing/rest/generateToken'; //Federated evn.,  use Portal  to generate user token.

    if(username && password){
      this.httpClient.post(tokenUrl, this.getCredentials(username, password), this.getHttpOptions()).subscribe(esriResponse =>{
        sessionStorage.setItem('dev_access_token', esriResponse['token']);
        sessionStorage.setItem('dev_access_token_expires', esriResponse['expires']);
      });;
    }
  }

  private getCredentials(username, password){
    let expiration = 720; //1440 -> 60 minute * 24 = 1 day token , 720 ->  12hrs token 
    
let urlReferer = 'https://'+window.location.host+'/';     
 
 let tokenCredentials =  'username='+username+'&password='+password+'&f=json&expiration='+expiration+'&client=referer&referer='+urlReferer;

    return tokenCredentials;
  }

  private getHttpOptions(){
    let httpOptions = {
      headers: new HttpHeaders({ 'Content-Type': 'application/x-www-form-urlencoded', }),
      withCredentials: true,            
    };
    return httpOptions;
  }

 

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