digitalmars.D.learn - Display a random image with vibe.d
- vnr (60/60) Jun 20 2021 Hello,
- pilger (4/9) Jun 20 2021 maybe this works:
- jfondren (21/24) Jun 20 2021 ```
- vnr (7/31) Jun 20 2021 Thanks for the answers, I understand better what is going on.
- jfondren (8/14) Jun 20 2021 Responding with a random image is an option, but what you have is
- vnr (30/50) Jun 20 2021 Great, thanks a lot, it works as expected! Here is the code used
- =?UTF-8?Q?Christian_K=c3=b6stlin?= (24/84) Jun 21 2021 The Random object should only be created once, but here its created for
Hello,
I would like to display a random image each time a page is
refreshed. I think my random function works, but the image does
not appear on the page. I have this template:
```
/public
/images
/rndimg
img1.jpg
img2.jpg
img3.jpg
/source
app.d
/views
index.dt
```
index.dt:
```
doctype html
html(lang="en")
head
meta(charset="UTF-8")
meta(name="viewport", content="width=device-width,
initial-scale=1.0")
meta(http-equiv="X-UA-Compatible", content="ie=edge")
title Document
body
```
And the code itself is:
```
import vibe.vibe;
void main()
{
auto settings = new HTTPServerSettings;
settings.port = 8080;
settings.bindAddresses = ["::1", "127.0.0.1"];
auto listener = listenHTTP(settings, &index);
scope (exit)
listener.stopListening();
logInfo("Please open http://127.0.0.1:8080/ in your browser.");
runApplication();
}
/// The index page
void index(HTTPServerRequest req, HTTPServerResponse res)
{
import std.random;
import std.format;
auto rnd = Random(unpredictableSeed);
auto a = uniform(1, 3, rnd);
const auto rndimg = format("images/rndimg/img%d.jpg", a);
res.render!("index.dt", req, rndimg);
}
```
I don't understand why the image doesn't display, when I take an
image from the internet and give the url, it works fine though.
Also, is this a good way to randomly display an image or is there
a way that is maybe cleaner/efficient?
Thank you.
Jun 20 2021
pilger <abcd dcba.com> On Sunday, 20 June 2021 at 12:34:33 UTC, vnr wrote:I don't understand why the image doesn't display, when I take an image from the internet and give the url, it works fine though.maybe this works: const auto rndimg = format("/images/rndimg/img%d.jpg", a);Also, is this a good way to randomly display an image or is there a way that is maybe cleaner/efficient?i would use the a/b testing capabilities of the webserver.
Jun 20 2021
On Sunday, 20 June 2021 at 12:34:33 UTC, vnr wrote:I don't understand why the image doesn't display, when I take an image from the internet and give the url, it works fine though.``` $ curl -s http://127.0.0.1:8080/|grep img <img src="images/rndimg/img2.jpg"/> ``` This is a relative URL, so to satisfy it the browser will tack it onto the end of the current request, making a request like the following: ``` $ curl -s http://127.0.0.1:8080/images/rndimg/img2.jpg|grep img <img src="images/rndimg/img2.jpg"/> ``` ... which is answered, not with an image, but with the random-image page. Your webserver needs to serve images if it's going to be asking visitors to ask it for images. Right now your webserver *only* tells visitors to ask it for images. Your webserver will also always recommend the same image.
Jun 20 2021
On Sunday, 20 June 2021 at 13:06:20 UTC, jfondren wrote:On Sunday, 20 June 2021 at 12:34:33 UTC, vnr wrote:Thanks for the answers, I understand better what is going on. So, what should I do to make my server respond with a random image, and not the random image page? I'm fairly new to vibe.d, so I don't yet know the intricacies of how to handle this style of thing and I couldn't find how to do it in the documentation. Thank you.I don't understand why the image doesn't display, when I take an image from the internet and give the url, it works fine though.``` $ curl -s http://127.0.0.1:8080/|grep img <img src="images/rndimg/img2.jpg"/> ``` This is a relative URL, so to satisfy it the browser will tack it onto the end of the current request, making a request like the following: ``` $ curl -s http://127.0.0.1:8080/images/rndimg/img2.jpg|grep img <img src="images/rndimg/img2.jpg"/> ``` ... which is answered, not with an image, but with the random-image page. Your webserver needs to serve images if it's going to be asking visitors to ask it for images. Right now your webserver *only* tells visitors to ask it for images. Your webserver will also always recommend the same image.
Jun 20 2021
On Sunday, 20 June 2021 at 13:58:22 UTC, vnr wrote:Thanks for the answers, I understand better what is going on. So, what should I do to make my server respond with a random image, and not the random image page? I'm fairly new to vibe.d, so I don't yet know the intricacies of how to handle this style of thing and I couldn't find how to do it in the documentation. Thank you.Responding with a random image is an option, but what you have is a good start, you just need to also serve images on request. I'm very distracted right now or I would've included more in my earlier post, but Vibe's online documentation has what you need. Try, especially, https://vibed.org/docs#http-routing You want a route for the random-image page, and you want to serve static files under images/
Jun 20 2021
On Sunday, 20 June 2021 at 14:28:26 UTC, jfondren wrote:On Sunday, 20 June 2021 at 13:58:22 UTC, vnr wrote:Great, thanks a lot, it works as expected! Here is the code used (app.d), for those who are interested: ``` import vibe.vibe; void main() { auto router = new URLRouter; router.get("/", &index); router.get("*", serveStaticFiles("public")); auto settings = new HTTPServerSettings; settings.bindAddresses = ["::1", "127.0.0.1"]; settings.port = 8080; auto listener = listenHTTP(settings, router); scope (exit) listener.stopListening(); logInfo("Please open http://127.0.0.1:8080/ in your browser."); runApplication(); } /// The index page void index(HTTPServerRequest req, HTTPServerResponse res) { import std.random; import std.format; auto rnd = Random(unpredictableSeed); const auto rndimg = format("/images/rndimg/img%d.jpg", uniform(1, 27, rnd)); res.render!("index.dt", req, rndimg); } ```Thanks for the answers, I understand better what is going on. So, what should I do to make my server respond with a random image, and not the random image page? I'm fairly new to vibe.d, so I don't yet know the intricacies of how to handle this style of thing and I couldn't find how to do it in the documentation. Thank you.Responding with a random image is an option, but what you have is a good start, you just need to also serve images on request. I'm very distracted right now or I would've included more in my earlier post, but Vibe's online documentation has what you need. Try, especially, https://vibed.org/docs#http-routing You want a route for the random-image page, and you want to serve static files under images/
Jun 20 2021
On 2021-06-20 17:14, vnr wrote:On Sunday, 20 June 2021 at 14:28:26 UTC, jfondren wrote:The Random object should only be created once, but here its created for every request. 1. It is relatively slow to reinitialize it 2. If you really want to have uniform distribution its probably better to not throw the UniformRandomNumberGenerator generator away. You can simplify that by using just uniform(1, 27) (it should fallback to the default rndGen that is initialized per thread (https://dlang.org/library/std/random/rnd_gen.html). here a benchmark of both functions: ``` import std; import std.datetime.stopwatch; auto onlyUniform() { return uniform(1, 27); } auto withNewRandom() { auto rnd = Random(unpredictableSeed); return uniform(1, 27, rnd); } void main() { 100_000.benchmark!(onlyUniform, withNewRandom).writeln; } ```On Sunday, 20 June 2021 at 13:58:22 UTC, vnr wrote:Great, thanks a lot, it works as expected! Here is the code used (app.d), for those who are interested: ``` import vibe.vibe; void main() { auto router = new URLRouter; router.get("/", &index); router.get("*", serveStaticFiles("public")); auto settings = new HTTPServerSettings; settings.bindAddresses = ["::1", "127.0.0.1"]; settings.port = 8080; auto listener = listenHTTP(settings, router); scope (exit) listener.stopListening(); logInfo("Please open http://127.0.0.1:8080/ in your browser."); runApplication(); } /// The index page void index(HTTPServerRequest req, HTTPServerResponse res) { import std.random; import std.format; auto rnd = Random(unpredictableSeed); const auto rndimg = format("/images/rndimg/img%d.jpg", uniform(1, 27, rnd)); res.render!("index.dt", req, rndimg); } ```Thanks for the answers, I understand better what is going on. So, what should I do to make my server respond with a random image, and not the random image page? I'm fairly new to vibe.d, so I don't yet know the intricacies of how to handle this style of thing and I couldn't find how to do it in the documentation. Thank you.Responding with a random image is an option, but what you have is a good start, you just need to also serve images on request. I'm very distracted right now or I would've included more in my earlier post, but Vibe's online documentation has what you need. Try, especially, https://vibed.org/docs#http-routing You want a route for the random-image page, and you want to serve static files under images/
Jun 21 2021