Download files from url to local device in .Net Core

Question

In .Net 4.0 I used WebClient to download files from an url and save them on my local drive. But I am not able to achieve the same in .Net Core.

Can anyone help me out on this?

Are you sure asp.net-core-mvc is the right tag? From your question it seems you're talking about client software. Either way: Use `HttpClient` if you want to download files. — jAC, Aug 30 '17 at 11:55

score 39 · Accepted Answer · edited Dec 15 '18 at 17:09

39

WebClient is not available in .NET Core. (UPDATE: It is from 2.0) The usage of HttpClient in the System.Net.Http is therefore mandatory:

using System.Net.Http;
using System.Threading.Tasks;
...
public static async Task<byte[]> DownloadFile(string url)
{
    using (var client = new HttpClient())
    {

        using (var result = await client.GetAsync(url))
        {
            if (result.IsSuccessStatusCode)
            {
                return await result.Content.ReadAsByteArrayAsync();
            }

        }
    }
    return null;
}

edited Dec 15 '18 at 17:09

Eduardo Molteni

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answered Aug 30 '17 at 12:07

jAC

5,195
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14

For readers, be aware that you shouldn't use HttpClient this way. An option is to let HttpClientFactory handle the lifetime of an Httpclient object. Read [more](https://stackoverflow.com/questions/50912160/should-httpclient-instances-created-by-httpclientfactory-be-disposed) – Kristianne Nerona Aug 06 '19 at 00:47

score 24 · Answer 2 · answered Dec 15 '18 at 17:08

24

WebClient is available from .net core 2.0

var wc = new System.Net.WebClient();
wc.DownloadFile( URL, @"c:\temp\myfile.txt");

answered Dec 15 '18 at 17:08

Eduardo Molteni

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1

Good to know, when you really want to download a file instead of using the content. – jAC Dec 18 '18 at 11:51
What happens if the remote file is not accessible, or the URL is wrong? Is there some way to know if the file was successfully downloaded or not? – Stian Mar 26 '19 at 12:31
1

@Stian It throws an exception – Eduardo Molteni Mar 27 '19 at 13:48
you should stop using webclient. – Leandro Bardelli Sep 26 '20 at 23:14
1

@Leandro: why?. – Eduardo Molteni Sep 28 '20 at 13:35
To begin, is not async. There is a lot of information about it, for e.g. this post is 6 yo: https://stackoverflow.com/questions/20530152/deciding-between-httpclient-and-webclient – Leandro Bardelli Sep 28 '20 at 13:40
2

You have the `DownloadFileAsync` method (this is .net core) – Eduardo Molteni Sep 30 '20 at 16:43

score 6 · Answer 3 · answered Apr 05 '22 at 10:27

In NetCore 6.0, you should use HttpClient instead of WebClient which is obsolete, and you have the async methods in the new File class.

The implementation is simple as the following:

static async Task DownloadFile(string url, string pathToSave, string fileName)
{
    var content = await GetUrlContent(url);
    if (content != null)
    {
        if (!Directory.Exists(pathToSave)) Directory.CreateDirectory(pathToSave);
        await File.WriteAllBytesAsync($"{pathToSave}/{fileName}", content);
    }
}

static async Task<byte[]?> GetUrlContent(string url)
{
    using (var client = new HttpClient())
    using (var result = await client.GetAsync(url))
        return result.IsSuccessStatusCode ? await result.Content.ReadAsByteArrayAsync():null;
}

Usage:

await DownloadFile("https://exampl.com/image.jpg", @"c:\DownloadedImages", "image.jpg");

This answer is nearly perfect, however it's generally not considered best practice to instantiate HttpClient using the constructor directly unless you are certain you will only do this once in the application lifetime. Better to construct a singleton to be reused or use IHttpClientFactory (personal favorite). More info here: https://learn.microsoft.com/en-us/dotnet/fundamentals/networking/httpclient-guidelines — Luke, Jun 29 '22 at 14:01

Download files from url to local device in .Net Core

3 Answers3