Sunday, April 20, 2014

HTML5 Geolocation

Code download available at the bottom of the post

In this tutorial we will use Jquery,Goople Api and HTML5 to capture geolocation
Browser used:Google Chrome

Step 1:
Include the Jquery and Goople maps API as shown below
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js" type="text/javascript"></script>
    <script src="http://maps.google.com/maps/api/js?sensor=true"></script>

Step 2:
Add a place holder for the Map
<div id="map"> </div>
Using HTML5 feature we will display the latitude and longitude, so add placeholders for latitude and longitude.
 <div id="lat"></div>
<div id="long"></div>

Step 3:
 Start writing code to capture the Geolocation
<script>
//using navigator (Html 5 feature) to get the Geolocation
x = navigator.geolocation;
x.getCurrentPosition(sucess,failure);

'getCurrentPosition' method has 2 argument, one when the function success and other for failure

If the browser supports HTML5 success method is invoked else the failure method is invoked.
In the failure method we will show a warning message to user as shown below..

function failure()
{
        //Using Jquery we will display the warning message in the lat DIV element.
$('#lat').html("<p>It din't work, co-ordinated not available</p>")
}

Step 4:
We will implement the Success method to display the Geolocation
We use the position variable in the success method to get the latitude and longitude
//Fetch the co-ordinates 
var mylat=position.coords.latitude;
var mylong = position.coords.longitude;
//Display the co-ordinates in the mylat and mylong DIV elements respectively
$('#lat').html(mylat)
$('#long').html(mylong)

Open up Google chrome, you will see the longitude and latitude if successful or the error message in case of unsupported browsers.

Step 5:
Now using the google API we will display the map
//Declare the coords variable to hold the co-ordinates
var coords = new google.maps.LatLng(mylat,mylong);

//Setting up our Google Map
We are going to specify three different parameters
i. Zoom,
ii.Co-ordinates
iii.Type of map (In this case we will define a road map)

var mapOptions = {zoom:16,
center:coords,

mapTypeId:google.maps.MapTypeId.ROADMAP}

//Creating a map
We will feed in 2 arguments, one the element which we want to override and fill our Map div element
Argument 1: document.getElementById("map") //get the div map element
Argument 2: Map settings which we defined earlier

var map=new google.maps.Map(document.getElementById("map"),mapOptions);

Step 6: 
Add some styles to the div element to view the map properly
<style type="text/css">
#map
{
height: 400px;width: 400px;
}
</style>

Step 7:
Add marker to specify the exact location
 //Create a marker
           var marker = new google.maps.Marker({ map: map, position: coords });





Save and open the page in Google Chrome



Note: Please change the browser setting to allow the application to access the geolocations
Browser Setting -> Advance Settings -> Privacy Settings -> Content settings -> Location ........

Download Code




Thursday, April 17, 2014

How to find a column reference in a given database schema

Run the below query
SELECT T.NAME AS TABLE_NAME,SCHEMA_NAME(SCHEMA_ID) AS SCHEMA_NAME,C.NAME AS COLUMN_NAME
FROM SYS.TABLES AS T
INNER JOIN SYS.COLUMNS C ON T.OBJECT_ID = C.OBJECT_ID
WHERE C.NAME LIKE '%User%'
ORDER BY SCHEMA_NAME, TABLE_NAME;

Output:



Wednesday, April 16, 2014

Change default browser in visual studio

Step 1: Right-click on an ASPX page within a Web Project and click "Browse With..."
Step 2: From this dialog you can click Set Default
Step 3: You can add other browsers, like Google Chrome to this dialog via Add

Jquery not working

6 steps to take if your jQuery is not working

1. The file is not there or does not exist

People tend to become upset and/or frustrated (Including me) when something simple doesn’t work, such as jQuery not working. Before you do anything, navigate to your jQuery file and check that it is exactly where it should be.

Also make sure that you have the correct html file open – I have actually tried to load files using the incorrect html, so the path would have been correct if I had the correct html file open. Don’t ever be too proud to check the absolute basics.

2. Incorrect File Path

This is a common problem and it is the first thing I check when I’m having a javascript problem (I actually do step 1 and 2 with my style.css as well). After checking that the file path is correct, I double check by viewing the page source using Firefox, I then click on the .js link. If it opens up the jQuery file (Double check it is opening the correct file) then the destination is correct. If it does not, or it opens a page-not-found, then I know I have a problem with my file path.

3. Script load order

Help! jQuery not working, however it is loading perfectly!!!
Make sure that it is the first script loaded on your page. This is very easy to overlook. The problem exists because browsers understand javascript and not stand alone jQuery snippets. jQuery turns our code into normal javascript code, so that the browsers can interpret what we are saying. Javascript libraries are shortcuts.
If you were to load a library plugin before the library itself has been loaded, the plugin would be seen as bunch of mumbo-jumbo by the browser. This snippet of code means absolute nothing before the library has been loaded.

4. Plugin not working

Plugins malfunction sometimes, for whatever reason; And people sometimes tend to think that jQuery is not working, which isn’t always the case. When it gets this far I think to myself, “Lets get out the big guns”.
Note: Step 1 and 2 can also be applied to CSS problems.
Even though I have tried step 1, step 2 and step 3, I do ANOTHER test to make 100% sure that it is loading properly. 99.999% of the time this is the final test.
Firstly, I make sure there are absolutely NO plugins, other libraries or anything javascript related on my page, except for the jQuery library and a little script I write beneath it.
<script type='text/javascript' src='http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js'></script>
<script type="text/javascript">
$(document).ready(function(){ 
         
 $("div").css("border", "3px solid red");
 
});
</script>
This adds a 3px red border to every single div on the page.
If this works, which it really should, the library is loading correctly. You then know that there is something wrong with the plugin(s) and that it is time for more troubleshooting. If you have more than one plugin, try switching the plugin order (This has worked for me on a few occasions), if it is still unsuccessful then remove each plugin and test until something works. Once you find the problem plugin, download it’s latest available version and see if it works.
If the 3px red border does not show up, then it’s time to jump to the next step.

5. Javascript library issues

Do not use multiple javascript libraries simultaneously! There are a few reasons to avoid this even besides the conflicts that could occur. More .js libraries means more html requests and more things to load. It doesn’t matter what .js library you use, use which ever you prefer more but stick with it throughout your project. There are thousands of jQuery plugins, I would say that 99% of the time there is no need for multiple libraries anyway.

6. Javascript disabled/not supported by browser

Make sure you are using a modern browser, and not IE 5.5 or something old and outdated.
It is possible to turn off the javascript support within a browser, and I have had this problem before (I actually turned off javascript support and forgot to turn it back on).
jQuery not working by this point? Try viewing the page with a different modern browser and see if there is any difference or make sure that javascript is enabled within the browser. This is a last resort.

Tips

  • Don’t load two different javascript library versions, only one is ever needed.
  • I have started loading jquery through Google at all times:
<script type='text/javascript' src='http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js?ver=1.4.2'></script>
The only downside to doing this that I can think of is if you are working offline (Obviously it won’t load) or if Google goes down for whatever reason.
  • Step 1, 2 and 3 can be applied to CSS files too. The Step 3 load order could refer to the IE specific stylesheets loading before the main one.
  • jQuery not working? Then follow the 6 steps again :)
  • Feel free to comment and ask for help if any is needed.

Friday, April 11, 2014

Difference between HTTP Post and HTTP Get

In an HTTP GET request, key/value pairs are specified in the URL:  

http://Aditya/PageName?value1=foo&value2=bar 

In an HTTP POST request, key/value pairs are sent as part of the HTTP request after the headers.
For example: 

 POST /something HTTP/1.1  Host: server  Content-Length: 21  Content-Type: application/x-www-form-urlencoded 


It's hard to really describe one as being more or less secure than the other, but HTTP POST data is not visible in the URL, and when submitting data to a website, an HTTP POST can usually only be performed as a result of user interaction (for example clicking on a "Submit" button). 

This means a user can't be tricked into visiting a URL like http://Aditya/update_profile?name=I_Test and sensitive data is not exposed in the URL. 

You can also use nonces and other anti-forgery tokens with html forms (which use POST) to prevent other forms of cross-site request forgeries. 

In general, POST should be used for requests that potentially modify state on the server, and GET should be used for read-only operations.