Autocomplete with Large Dataset - ASP.Net

 Friends, You might have used jquery autocomplete to a search field in your website. But have you ever wondered to deal with large datasets? JQuery auto complete makes the page unresponsive with it's search if there are lot of data to filter. Below is the solution to that. 

Original post for this can be found here

     function autocomplete(inp, arr) {  
       /*the autocomplete function takes two arguments,  
       the text field element and an array of possible autocompleted values:*/  
       var currentFocus;  
       /*execute a function when someone writes in the text field:*/  
       inp.addEventListener("input", function (e) {  
         var a, b, i, val = this.value;  
         /*close any already open lists of autocompleted values*/  
         closeAllLists();  
         if (!val) { return false; }  
         currentFocus = -1;  
         /*create a DIV element that will contain the items (values):*/  
         a = document.createElement("DIV");  
         a.setAttribute("id", this.id + "autocomplete-list");  
         a.setAttribute("class", "autocomplete-items");  
         /*append the DIV element as a child of the autocomplete container:*/  
         this.parentNode.appendChild(a);  
         /*for each item in the array...*/  
         for (i = 0; i < arr.length; i++) {  
           /*check if the item starts with the same letters as the text field value:*/  
           if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {  
             /*create a DIV element for each matching element:*/  
             b = document.createElement("DIV");  
             /*make the matching letters bold:*/  
             b.innerHTML = "<strong>" + arr[i].substr(0, val.length) + "</strong>";  
             b.innerHTML += arr[i].substr(val.length);  
             /*insert a input field that will hold the current array item's value:*/  
             b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";  
             /*execute a function when someone clicks on the item value (DIV element):*/  
             b.addEventListener("click", function (e) {  
               /*insert the value for the autocomplete text field:*/  
               inp.value = this.getElementsByTagName("input")[0].value;  
               /*close the list of autocompleted values,  
               (or any other open lists of autocompleted values:*/  
               closeAllLists();  
             });  
             a.appendChild(b);  
           }  
         }  
       });  
       /*execute a function presses a key on the keyboard:*/  
       inp.addEventListener("keydown", function (e) {  
         var x = document.getElementById(this.id + "autocomplete-list");  
         if (x) x = x.getElementsByTagName("div");  
         if (e.keyCode == 40) {  
           /*If the arrow DOWN key is pressed,  
           increase the currentFocus variable:*/  
           currentFocus++;  
           /*and and make the current item more visible:*/  
           addActive(x);  
         } else if (e.keyCode == 38) { //up  
           /*If the arrow UP key is pressed,  
           decrease the currentFocus variable:*/  
           currentFocus--;  
           /*and and make the current item more visible:*/  
           addActive(x);  
         } else if (e.keyCode == 13) {  
           /*If the ENTER key is pressed, prevent the form from being submitted,*/  
           e.preventDefault();  
           if (currentFocus > -1) {  
             /*and simulate a click on the "active" item:*/  
             if (x) x[currentFocus].click();  
           }  
         }  
       });  
       function addActive(x) {  
         /*a function to classify an item as "active":*/  
         if (!x) return false;  
         /*start by removing the "active" class on all items:*/  
         removeActive(x);  
         if (currentFocus >= x.length) currentFocus = 0;  
         if (currentFocus < 0) currentFocus = (x.length - 1);  
         /*add class "autocomplete-active":*/  
         x[currentFocus].classList.add("autocomplete-active");  
       }  
       function removeActive(x) {  
         /*a function to remove the "active" class from all autocomplete items:*/  
         for (var i = 0; i < x.length; i++) {  
           x[i].classList.remove("autocomplete-active");  
         }  
       }  
       function closeAllLists(elmnt) {  
         /*close all autocomplete lists in the document,  
         except the one passed as an argument:*/  
         var x = document.getElementsByClassName("autocomplete-items");  
         for (var i = 0; i < x.length; i++) {  
           if (elmnt != x[i] && elmnt != inp) {  
             x[i].parentNode.removeChild(x[i]);  
           }  
         }  
       }  
       /*execute a function when someone clicks in the document:*/  
       document.addEventListener("click", function (e) {  
         closeAllLists(e.target);  
       });  
     }  

And you will have to apply the following CSS.

 /*the container must be positioned relative:*/  
 .autocomplete {  
   position: relative;  
   display: inline-block;  
 }  
 .autocomplete-items {  
   position: absolute;  
   border: 1px solid #d4d4d4;  
   border-bottom: none;  
   border-top: none;  
   z-index: 99;  
   /*position the autocomplete items to be the same width as the container:*/  
   top: 100%;  
   left: 0;  
   right: 0;  
   max-height: 300px;  
   /*height: 300px;*/  
   overflow-y: auto;  
   margin-left: 20px;  
 }  
   .autocomplete-items div {  
     padding: 5px 15px;  
     cursor: pointer;  
     background-color: #fff;  
     border-bottom: 1px solid #d4d4d4;  
   }  
     /*when hovering an item:*/  
     .autocomplete-items div:hover {  
       background-color: #e9e9e9;  
     }  
 /*when navigating through the items using the arrow keys:*/  
 .autocomplete-active {  
   background-color: DodgerBlue !important;  
   color: #ffffff;  
 }  

Then the reference can be made as below;

 autocomplete(document.getElementById("txtSearch"), keywords);  

Keywords are the array of strings to search. So, it will look like below eventually,

Unlike jquery autocomplete, this doesn't slowdown your page. 

Happy coding..

Base64 - Encoding and Decoding s String

The following class can be used to encode a string or decode an encoded string. 

   public static class Base64  
   {  
     public static string Encode(this System.Text.Encoding encoding, string textValue)  
     {  
       if (textValue == null)  
       {  
         return null;  
       }  
       try  
       {  
         byte[] textAsBytes = encoding.GetBytes(textValue);  
         return System.Convert.ToBase64String(textAsBytes);  
       }  
       catch (Exception)  
       {  
         return textValue;  
       }        
     }  
     public static string Decode(this System.Text.Encoding encoding, string encodedTextValue)  
     {  
       if (encodedTextValue == null)  
       {  
         return null;  
       }  
       try  
       {  
         byte[] textAsBytes = System.Convert.FromBase64String(encodedTextValue);  
         return encoding.GetString(textAsBytes);  
       }  
       catch (Exception)  
       {  
         return encodedTextValue;  
       }        
     }  
   }  

So, you can refer this as below;

 EncodingForBase64.DecodeBase64(Encoding.UTF8, yourtextvalue);  

Happy coding...

Convert an Image to Base64

Base64 encoded files are larger than the original. The advantage lies in not having to open another connection and make a HTTP request to the server for the image. This benefit is lost very quickly so there's only an advantage for large numbers of very tiny individual images.

Link to the Question

However we may still need to convert an image to base64 on the way to display our data on HTML page. Assuming you have a class that represent all the necessary details, here is how you can have an additional property to the class that converts images to base64.

     public string imageBase64  
     {  
       get  
       {  
         using (var client = new WebClient())  
         {  
           byte[] dataBytes = client.DownloadData(new Uri(image));  
           string encodedFileAsBase64 = Convert.ToBase64String(dataBytes);  
           return "data:image/jpeg;base64," + encodedFileAsBase64;  
         }  
       }  
     }  

Copy this and try it in your code. it will generate your html image tag as below.

Happy Coding...

Writing a class to access mongo db end points in C#

Not knowing MongoDB? Read it here: 

https://en.wikipedia.org/wiki/MongoDB

"MongoDB is a source-available cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas. "

Today we talk about how to write a common class to access end points ( Hosted seperately) that allow us to access MongoDB collection. You can read / write collections through this.

Lets go straight to the code:

   public class MongoService  
   {  
     public XmlDocument Select(Method method, string ServiceAddress, Dictionary<string, string> Header, Dictionary<string, object> Parameter)  
     {  
       var client = new RestClient(ServiceAddress);  
       client.Timeout = -1;  
       var request = new RestRequest(method);  
       foreach (var h in Header)  
         request.AddHeader(h.Key, h.Value);  
       foreach (var p in Parameter)  
         request.AddParameter(p.Key, p.Value);  
       IRestResponse response = client.Execute(request);  
       if (string.IsNullOrEmpty(response.Content))  
         return null;  
       var node = JsonConvert.DeserializeXNode(response.Content, "Root");  
       string xml = node.ToString();  
       XmlDocument doc = new XmlDocument();  
       doc.LoadXml(xml);  
       return doc;  
     }  
     public string Select<T>(Method method, string ServiceAddress, Dictionary<string, string> Header, Dictionary<string, object> Parameter)  
     {  
       var client = new RestClient(ServiceAddress);  
       client.Timeout = -1;  
       var request = new RestRequest(method);  
       foreach (var h in Header)  
         request.AddHeader(h.Key, h.Value);  
       foreach (var p in Parameter)  
         request.AddParameter(p.Key, p.Value);  
       IRestResponse response = client.Execute(request);  
       return response.Content;  
     }  
     public string Select<T>(Method method, string ServiceAddress, Dictionary<string, string> Header)  
     {  
       var client = new RestClient(ServiceAddress);  
       client.Timeout = -1;  
       var request = new RestRequest(method);  
       foreach (var h in Header)  
         request.AddHeader(h.Key, h.Value);  
       IRestResponse response = client.Execute(request);  
       return response.Content;  
     }  
     public string Save<T>(Method method, string ServiceAddress, Dictionary<string, string> Header, Dictionary<string, object> Parameter)  
     {  
       var client = new RestClient(ServiceAddress);  
       client.Timeout = -1;  
       var request = new RestRequest(method);  
       foreach (var h in Header)  
         request.AddHeader(h.Key, h.Value);  
       foreach (var p in Parameter)  
         request.AddParameter(p.Key, p.Value);  
       IRestResponse response = client.Execute(request);  
       return response.Content;  
     }  
     public string Update<T>(Method method, string ServiceAddress, Dictionary<string, string> Header, Dictionary<string, object> Parameter)  
     {  
       var client = new RestClient(ServiceAddress);  
       client.Timeout = -1;  
       var request = new RestRequest(method);  
       foreach (var h in Header)  
         request.AddHeader(h.Key, h.Value);  
       foreach (var p in Parameter)  
         request.AddParameter(p.Key, p.Value);  
       IRestResponse response = client.Execute(request);  
       return response.Content;  
     }  
     public string Delete<T>(Method method, string ServiceAddress, Dictionary<string, string> Header, Dictionary<string, object> Parameter)  
     {  
       var client = new RestClient(ServiceAddress);  
       client.Timeout = -1;  
       var request = new RestRequest(method);  
       foreach (var h in Header)  
         request.AddHeader(h.Key, h.Value);  
       foreach (var p in Parameter)  
         request.AddParameter(p.Key, p.Value);  
       IRestResponse response = client.Execute(request);  
       return response.Content;  
     }  
   }  

The MongoService class has the following methods.

public XmlDocument Select(Method method, string ServiceAddress, Dictionary<string, string> Header, Dictionary<string, object> Parameter)  

This return the result as an xml document.

The parameters contain;

• Method
• ServiceAddress
• Header
• Parameter

The method is the restsharp method as it is GET or POST or any other.

Service address is the service address.

Header is the Dictionary of strings for headers.

Parameter is the Dictionary of string and object values for the parameters.

Using this class will help to ease with dealing the end points.

Happy coding.

Creating country flag emoji from country code - c#

Sometimes you might need to show the country flag as an icon or imoji in your webpage. But we don't need to host images of country flags anywhere which we can create images from the code itself. look at the below code.

 public static string CountryCodeToFlag(this string country)  
     {  
       return string.Concat(country.ToUpper().Select(x => char.ConvertFromUtf32(x + 0x1F1A5)));  
     }  

This is an extension method. so we can use it as below.

 "us".CountryCodeToFlag()  

The result will look like below,

Happy coding...

c# - App.config - read and write - easy way

Let's discuss about how we can read and write App.Config file in a easy way. Before that if you need to know more about what is this file, read this post https://blog.submain.com/app-config-basics-best-practices/

Lets get back to code.

     public static bool UpdateAppSettings(string key, string value)  
     {  
       try  
       {  
         var configFile = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);  
         var settings = configFile.AppSettings.Settings;  
         if (settings[key] == null)  
         {  
           settings.Add(key, value);  
         }  
         else  
         {  
           settings[key].Value = value;  
         }  
         configFile.Save(ConfigurationSaveMode.Modified);  
         ConfigurationManager.RefreshSection(configFile.AppSettings.SectionInformation.Name);  
         return true;  
       }  
       catch (Exception)  
       {  
         throw;  
       }  
     }  

     public static string ReadAppSetting(string key)  
     {  
       try  
       {  
         return ConfigurationManager.AppSettings[key];  
       }  
       catch (Exception)  
       {  
         throw;  
       }  
     }  

UpdateAppSettings and ReadAppSetting are two methods we use. lets say we have a config value like below.



We can read and update this values as this.

 public static string ConString { get { return ReadAppSetting("ConString"); } set { UpdateAppSettings("ConString", value); } }  

Hope you can get this applied to your need too.
Happy coding.

Creating Images from Text in C#

Sometimes you might need to create images from text. Following method can be used to do that.

 public static Image DrawText(String text, Font font, Color textColor, Color backColor)  
     {        
       Image img = new Bitmap(1, 1);  
       Graphics drawing = Graphics.FromImage(img);  
       SizeF textSize = drawing.MeasureString(text, font);  
       img.Dispose();  
       drawing.Dispose();  
       img = new Bitmap((int)textSize.Width, (int)textSize.Height);  
       drawing = Graphics.FromImage(img);  
       drawing.Clear(backColor);  
       drawing.SmoothingMode = SmoothingMode.AntiAlias;  
       drawing.InterpolationMode = InterpolationMode.HighQualityBicubic;  
       drawing.PixelOffsetMode = PixelOffsetMode.HighQuality;  
       drawing.TextRenderingHint = TextRenderingHint.SingleBitPerPixelGridFit;  
       Brush textBrush = new SolidBrush(textColor);  
       drawing.DrawString(text, font, textBrush, 0, 0);  
       drawing.Save();  
       textBrush.Dispose();  
       drawing.Dispose();  
       return img;  
     }  

Such scenario can be applied to a website like below, The logo is created from a text there.

Happy coding.
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