I'm trying to figure out how to render data that the server sends in an event. Let's say I write sse.write "test" or sse.write {name: "test"} to the browser. How would I be able to capture that into an element on the page? I know it can be viewed in curl... Could I implement that? I'm very new to rails.
You'll have to use JavaScript for this.
// app.js file loaded in the page
sse = new EventSource('localhost:3000/sse');
sse.addEventListener('message', function(e) {
text = document.createTextNode(e.data);
el.createElement('p').appendChild(text);
document.body.appendChild(el);
}, false);
Related
I'm new to ruby on rails. I'm trying to save data that is generated by itself to the database. i have looked into and found I was meant to use ajax, however all the videos/forums i have seen are example of ajax that use form and not refreshing page. i want to save data automatically without pressing submit.
Assume that the project is fresh project with postgresql as the database. I have created a database that can hold geo points by using postgis. i have created another page where it has map implemented where i can manully pin location. I want to save the manuuly pinned location to the database.
function onMapClick(e) {
alert("You clicked the map at " + e.latlng);
}
mymap.on('click', onMapClick);
var popup = L.popup();
function onMapClick(e) {
popup
.setLatLng(e.latlng)
.setContent("You clicked the map at " + e.latlng.toString())
.openOn(mymap);
}
mymap.on('click', onMapClick);
The e.latlng holds the geopoint, but i dont know how to save it the database if the user clicks anywhere on the map.
You don't need submit form to use ajax.
Basically what you want is add event listener to the map, and when user click then send ajax request to the controller.
For example, let's say that your map is inside div with id my-map.
If you use jQuery you can write something like this:
$('#my-map').on('click', function() {
# add your logic here
$.ajax({
url: 'your-url',
type: 'POST',
dataType: 'json',
contentType: "application/json; charset=utf-8",
data: JSON.stringify({
'let': data you want to send to backend
})
}
Hope it works!
EDIT:
After I looked your code I found that you can not have jQuery in your project so you can not use jQuery ajax. You need use vanilla javascript. So instead this snippet above, you can write this.
var xhttp = new XMLHttpRequest();
const params = { saving_location: { geoPoints: e.latlng } }
xhttp.onreadystatechange = function() {//Call a function when the state changes.
if(xhttp.readyState == 4 && xhttp.status == 200) {
alert(http.responseText);
}
}
xhttp.open("POST", "/saving_locations", true);
xhttp.setRequestHeader('Content-Type', 'application/json', 'Accept', 'application/json');
xhttp.send(JSON.stringify(params));
Also add protect_from_forgery with: :null_session in your application controller and skip_before_action :verify_authenticity_token in your Saving Location controller.(under before_action).
Here is good blog post why you need this https://blog.nvisium.com/understanding-protectfromforgery
Please notice that you wan't save your database, because your geoPoints type in database is type of point and you send string to rails controller. I never work with points in rails so I can not help you here.(You can always add two columns in db, one for longitude and one for latitude and then store numbers instead point)
I am looking to create a file on the fly and offer a download link to the user in a GRAILS application.
I followed the approach from here. I have no errors however it doesn't seem to work. Here's my controller code.
`render (file: pptFile, fileName:'someppt.pptx', contentType: 'application/octet-stream')
Client side code makes an AJAX call to retrieve the file from server. It does not cause the server to force downloading of the file on the client (browser). Here's the client side code.
$.ajax({
type : 'POST',
url : '<<URL>>',
success: function(result) {
var uri = 'data:application/octet-stream;charset=UTF-8,' +
encodeURIComponent(result);
window.open(uri, 'somePPT.pptx');
},
failure: function(){
alert ('failure')
}
});
Perhaps something akin to this (paraphrased, but used for downloading a json file):
def someControllerMethod() {
def dlContent = someService.marshalJson()
def contentType = "application/octet-stream"
def filename = "someFilename.json"
response.setHeader("Content-Disposition", "attachment;filename=${filename}")
render(contentType: contentType, text: dlContent as JSON)
}
okay. So I finally got this to work. As proposed by #railsdog and many others (This problem has been discussed on other threads in stackoverflow but the specific case I had was slightly different from those) I ended up writing to response directly from server and took out the AJAX call. The only reason I was doing an AJAX call was because I did not want to submit the current page that had the "generate file" functionality (There are many data elements on the page and I did not want to re-do the entire page just for downloading the file). So I ended up using an anchor tag with target as "_blank". Here's the code snippet
<a href="myControllerMethodToGenerateFileAndWriteToHTTPResponseDirectlyAsSuggestedByOthersInThisPost"
target="_blank"/>
This actually opened a new page and did the submission to initiate the download. Problem solved. It's working fine in CHROME. :) Thanks guys!
I like the solution using the render method from #railsdog !
A slightly other approach which I used so far was:
def controllerMethod() {
...
File file = sepaXmlService.createTransfersFile(...)
response.setContentType("application/xml")
response.setHeader("Content-disposition", "attachment;filename=${file.getName()}")
OutputStream out = response.getOutputStream()
out.write(file.bytes)
out.close()
file.delete()
return
...
}
In the view I use the following statement in the form:
<g:actionSubmit action="controllerMethod" class="btn" value="Get XML!" /></td>
I think it should also be possible to use a
<g:link controller="foobar" action="controllerMethod" class="btn">GetXML</g:link>
I have Entry model with url field, which contains link to external site.
In view I list these links, and now I'd like to start counting when someone clicks it, and keep this info in database. What's the best way of doing it?
You can easily use google analytics to track outbound links: http://support.google.com/analytics/bin/answer.py?hl=en&answer=1136920
If that is not an option you will need to add some javascript to your links make an ajax request to the server to increment the count before transferring the user to the new url. Something similar to this jquery code:
$('a').click(function(){
var stored_ulr = $(this).attr('href');
$.ajax({
url: #your server url to increment count,
data: #data you need to send,
success: function() { window.location = stored_url; },
});
return false;
});
The above code is just a general outline. You will have to fill in the blanks and make it work for your needs.
In my Grails application, a user can click on a g:link which will call my controller to export certain data to a CSV file. This works with no problems.
I then moved that button to a jQuery dialog box and, when the button is clicked, I use
${remoteFunction(action:'export', onSuccess:'closeMe();', id:courseInstance?.id)}
to call the same controller method and close the dialog box. I've confirmed that the method is actually called, and the dialog box closes. The user is not prompted with the CSV dowmload, however. I'm assuming this has something to do with the remoteFunction, but I'm not really sure. Can anyone explain why this might happen, and a potential fix?
Thanks!
With AJAX requests you can't handle to download content as attachment and so it can't trigger the Save As dialog.
There are a couple of workarounds for this:
Use a plain g:link as before and bind the 'closeMe();' function to the 'click' event. The problem is that you have no control on error or success response.
Use an iframe: You can create a temporary invisible iframe and set its location to the URL of the file to download. It also has the backside of not controlling the success/error response.
The code could be the same as in this answer:
<script type="text/javascript">
function downloadURL(url) {
var iframe;
var hiddenIFrameID = 'hiddenDownloader';
iframe = document.getElementById(hiddenIFrameID);
if (iframe === null) {
iframe = document.createElement('iframe');
iframe.id = hiddenIFrameID;
iframe.style.display = 'none';
document.body.appendChild(iframe);
}
iframe.src = url;
}
</script>
And the link
Export
I want to prefix URLs which match my patterns. When I open a new tab in Firefox and enter a matching URL the page should not be loaded normally, the URL should first be modified and then loading the page should start.
Is it possible to modify an URL through a Mozilla Firefox Addon before the page starts loading?
Browsing the HTTPS Everywhere add-on suggests the following steps:
Register an observer for the "http-on-modify-request" observer topic with nsIObserverService
Proceed if the subject of your observer notification is an instance of nsIHttpChannel and subject.URI.spec (the URL) matches your criteria
Create a new nsIStandardURL
Create a new nsIHttpChannel
Replace the old channel with the new. The code for doing this in HTTPS Everywhere is quite dense and probably much more than you need. I'd suggest starting with chrome/content/IOUtils.js.
Note that you should register a single "http-on-modify-request" observer for your entire application, which means you should put it in an XPCOM component (see HTTPS Everywhere for an example).
The following articles do not solve your problem directly, but they do contain a lot of sample code that you might find helpful:
https://developer.mozilla.org/en/Setting_HTTP_request_headers
https://developer.mozilla.org/en/XUL_School/Intercepting_Page_Loads
Thanks to Iwburk, I have been able to do this.
We can do this my overriding the nsiHttpChannel with a new one, doing this is slightly complicated but luckily the add-on https-everywhere implements this to force a https connection.
https-everywhere's source code is available here
Most of the code needed for this is in the files
IO Util.js
ChannelReplacement.js
We can work with the above files alone provided we have the basic variables like Cc,Ci set up and the function xpcom_generateQI defined.
var httpRequestObserver =
{
observe: function(subject, topic, data) {
if (topic == "http-on-modify-request") {
var httpChannel = subject.QueryInterface(Components.interfaces.nsIHttpChannel);
var requestURL = subject.URI.spec;
if(isToBeReplaced(requestURL)) {
var newURL = getURL(requestURL);
ChannelReplacement.runWhenPending(subject, function() {
var cr = new ChannelReplacement(subject, ch);
cr.replace(true,null);
cr.open();
});
}
}
},
get observerService() {
return Components.classes["#mozilla.org/observer-service;1"]
.getService(Components.interfaces.nsIObserverService);
},
register: function() {
this.observerService.addObserver(this, "http-on-modify-request", false);
},
unregister: function() {
this.observerService.removeObserver(this, "http-on-modify-request");
}
};
httpRequestObserver.register();
The code will replace the request not redirect.
While I have tested the above code well enough, I am not sure about its implementation. As far I can make out, it copies all the attributes of the requested channel and sets them to the channel to be overridden. After which somehow the output requested by original request is supplied using the new channel.
P.S. I had seen a SO post in which this approach was suggested.
You could listen for the page load event or maybe the DOMContentLoaded event instead. Or you can make an nsIURIContentListener but that's probably more complicated.
Is it possible to modify an URL through a Mozilla Firefox Addon before the page starts loading?
YES it is possible.
Use page-mod of the Addon-SDK by setting contentScriptWhen: "start"
Then after completely preventing the document from getting parsed you can either
fetch a different document from the same domain and inject it in the page.
after some document.URL processing do a location.replace() call
Here is an example of doing 1. https://stackoverflow.com/a/36097573/6085033