C# – How to use geonames API to get city name

cgeonameswindows-phone-7xml

How can i search the geonames using their API and get city name and coordinates?
Link to their API

Best Answer

Of course it depends entirely on the actual search you want to perform. Let's say you want to find all locations in Great Britain that start with Lon. The URL that will perform this search (as an example, much may change for a real search) is:

http://api.geonames.org/search?name_startsWith=lon&country=GB&maxRows=10&username=demo

You can pop that in your browser and see the results:

<geonames style="MEDIUM">
<totalResultsCount>334</totalResultsCount>
<geoname>
    <toponymName>London</toponymName>
    <name>London</name>
    <lat>51.50853</lat>
    <lng>-0.12574</lng>
    <geonameId>2643743</geonameId>
    <countryCode>GB</countryCode>
    <countryName>United Kingdom</countryName>
    <fcl>P</fcl>
    <fcode>PPLC</fcode>
</geoname>
<geoname>
    <toponymName>Lone</toponymName>
    <name>Lone</name>
    <lat>58.33333</lat>
    <lng>-4.88333</lng>
    <geonameId>2643732</geonameId>
    <countryCode>GB</countryCode>
    <countryName>United Kingdom</countryName>
    <fcl>P</fcl>
    <fcode>PPL</fcode>
</geoname>
<!-- and so on ... -->
</geonames>

Note that you want the lat and lng elements under each geoname. With LINQ to XML (include System.Linq and System.Linq.Xml in your namespace declarations):

var xml = XElement.Load("http://api.geonames.org/search?name_startsWith=lon&country=GB&maxRows=10&username=demo");

var locations = xml.Descendants("geoname").Select(g => new { 
                    Name = g.Element("name").Value, 
                    Lat = g.Element("lat").Value, 
                    Long = g.Element("lng").Value
                });

foreach (var location in locations)
{
    Console.WriteLine("{0}: {1}, {2}", location.Name, location.Lat, location.Long);
}

Of course you may choose to use these values differently, and you may want to parse Lat and Long into doubles.

Related Solutions

C# – Deep cloning objects

Whereas one approach is to implement the ICloneable interface (described here, so I won't regurgitate), here's a nice deep clone object copier I found on The Code Project a while ago and incorporated it into our code. As mentioned elsewhere, it requires your objects to be serializable.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;

/// <summary>
/// Reference Article http://www.codeproject.com/KB/tips/SerializedObjectCloner.aspx
/// Provides a method for performing a deep copy of an object.
/// Binary Serialization is used to perform the copy.
/// </summary>
public static class ObjectCopier
{
    /// <summary>
    /// Perform a deep copy of the object via serialization.
    /// </summary>
    /// <typeparam name="T">The type of object being copied.</typeparam>
    /// <param name="source">The object instance to copy.</param>
    /// <returns>A deep copy of the object.</returns>
    public static T Clone<T>(T source)
    {
        if (!typeof(T).IsSerializable)
        {
            throw new ArgumentException("The type must be serializable.", nameof(source));
        }

        // Don't serialize a null object, simply return the default for that object
        if (ReferenceEquals(source, null)) return default;

        using var Stream stream = new MemoryStream();
        IFormatter formatter = new BinaryFormatter();
        formatter.Serialize(stream, source);
        stream.Seek(0, SeekOrigin.Begin);
        return (T)formatter.Deserialize(stream);
    }
}

The idea is that it serializes your object and then deserializes it into a fresh object. The benefit is that you don't have to concern yourself about cloning everything when an object gets too complex.

In case of you prefer to use the new extension methods of C# 3.0, change the method to have the following signature:

public static T Clone<T>(this T source)
{
   // ...
}

Now the method call simply becomes objectBeingCloned.Clone();.

EDIT (January 10 2015) Thought I'd revisit this, to mention I recently started using (Newtonsoft) Json to do this, it should be lighter, and avoids the overhead of [Serializable] tags. (NB @atconway has pointed out in the comments that private members are not cloned using the JSON method)

/// <summary>
/// Perform a deep Copy of the object, using Json as a serialization method. NOTE: Private members are not cloned using this method.
/// </summary>
/// <typeparam name="T">The type of object being copied.</typeparam>
/// <param name="source">The object instance to copy.</param>
/// <returns>The copied object.</returns>
public static T CloneJson<T>(this T source)
{            
    // Don't serialize a null object, simply return the default for that object
    if (ReferenceEquals(source, null)) return default;

    // initialize inner objects individually
    // for example in default constructor some list property initialized with some values,
    // but in 'source' these items are cleaned -
    // without ObjectCreationHandling.Replace default constructor values will be added to result
    var deserializeSettings = new JsonSerializerSettings {ObjectCreationHandling = ObjectCreationHandling.Replace};

    return JsonConvert.DeserializeObject<T>(JsonConvert.SerializeObject(source), deserializeSettings);
}

C# – How to enumerate an enum

foreach (Suit suit in (Suit[]) Enum.GetValues(typeof(Suit)))
{
}

Note: The cast to (Suit[]) is not strictly necessary, but it does make the code 0.5 ns faster.

Best Answer

Related Solutions

C# – Deep cloning objects

C# – How to enumerate an enum

Related Topic