Finding Location with the Geolocation API - HTML5 Programming for ASP.NET Developers - page 316

});
});
});
This code shows the Show button's click event-handler function. It first retrieves the user's location
using the getCurrentPosition() method of the geolocation object. This time, a success function is
provided inline with the getCurrentPosition() call instead of as a separate function. The user's location's
latitude and longitude values are stored in the local variables lat1 and long1 . A JSON object with three
keys— lat1 , long1 , and distance —is formed using the values from the variables and the <input> ield.
Next, an Ajax request is made to the GetJobs() action method using the jQuery $.ajax() method.
GetJobs() returns zero or more Job objects and is discussed shortly. The success function of the $.ajax()
method receives the Job objects returned by GetJobs() . It then iterates through the jobs array and adds the
jobs to an HTML table. The table contains the Title , Description , and LocationName properties of the Job
objects.
The error-handler function of the $.ajax() method displays the error message in an alert box. The
GetJobs() action method that returns the relevant jobs based on the user's location and the specified
distance is shown in Listing 12-10.
Listing 12-10. GetJobs() Action Method
[HttpPost]
public JsonResult GetJobs(double lat1, double long1, double distance)
{
JobsDbEntities db = new JobsDbEntities();
var data = from item in db.Jobs
select item;
List<Job> selectedJobs = new List<Job>();
foreach(Job job in data)
{
var temp = from item in db.Locations
where item.LocationName==job.LocationName
select item;
double lat2 = (double)((Location)temp.SingleOrDefault()).Latitude;
double long2 = (double)((Location)temp.SingleOrDefault()).Longitude;
if (GetDistance(lat1, long1, lat2, long2) <= distance)
{
selectedJobs.Add(job);
}
}
var finalData = from obj in selectedJobs
orderby obj.LocationName
select obj;
return Json(finalData);
}
The GetJobs() action method from the Home controller takes three parameters of type double . The
lat1 and long1 parameters represent the latitude and longitude of the user's location. The distance
parameter represents the distance specified by the user. The method then iterates through all the available
job postings. With each iteration, the latitude and longitude of the job location are determined. The