I am using XPCOM to read/write file(s) on my hard drive (since Java is no longer supported on FF16,17,18,+ I have to use this). I use it in my FireFox extension(s) (I use iMacros). On this document click I found this example.
var string = '\u5909\u63db\u30c6\u30b9\u30c8';
file.initWithPath('C:\\temp\\temp.txt');
file.create(file.NORMAL_FILE_TYPE, 0666);
var charset = 'EUC-JP';
var fileStream = Components
.classes['#mozilla.org/network/file-output-stream;1']
.createInstance(Components.interfaces.nsIFileOutputStream);
fileStream.init(file, 2, 0x200, false);
var converterStream = Components
.classes['#mozilla.org/intl/converter-output-stream;1']
.createInstance(Components.interfaces.nsIConverterOutputStream);
converterStream.init(fileStream, charset, string.length,
Components.interfaces.nsIConverterInputStream.DEFAULT_REPLACEMENT_CHARACTER);
converterStream.writeString(string);
converterStream.close();
fileStream.close();
So this code does the following. If file doesn't exist it creates it and saves the data in it. However if file does exists it will return error.
If I comment that part of the code (and file exists) it will just overwrite the old data and put the new.
I need this code to create file, if it exists just move on without an error and save the data in the new line without overwriting.
Like this.
before:
data11, data12, data13
data21, data22, data23
after:
data11, data12, data13
data21, data22, data23
data31, data32, data33
data41, data42, data43
Try passing 18 as the second parameter when you init the output stream (instead of 2).
fileStream.init(file, 18, 0x200, false);
That adds the PR_APPEND flag to the io mode parameter (it's 0x10; the 2 is for PR_WRONLY).
Related
I have a simple html file in which there's javascript code referring to google charts.
The code I use is this (I'll show the important part):
function drawChart(){
var data = google.visualization
.arrayToDataTable([ ['Label', 'Value'],['Temp', 22.75],]);
// etc...
}
I use a bash command (sed) to replace that 22.75 value with a new one from the last line of a .txt file. However, this throws some errors which I haven't been able to neither correct nor ever identify.
So is there any javascript code that takes that file, extracts the last value and simply displays it on the right place of the code?
UPDATE:
Sorry for the lack of info in this question, I really appreciate all the people that took the time on reading my question. I'll try to fill with more information in the next minutes.
I am able to extract the last line of the .txt file, extract the value on the right part of the '-' symbol and store it in a variable. Then that value is taken to update the html file with a sed command. The error comes when the value is updated but with no value. I guess that happends due to a failed record of temperature in the txt file, then the extracted value is a null. Finally is the html fiel with javascrit code happens to be like this:
(...)['Temp', ],]);
Then the updater can't update the value since due to the way that sed command is written I guess there's no way that it can detect a no-number-value in there. So the html remains without a value all the time.
TXT File structure:
(...)
20:25:03-23.312
20:26:02-23.312
20:27:03-23.375
20:28:03-23.375
20:29:02-23.375
20:30:02-23.312
Bash script:
# (...code...)
lastRecord=`cat /home/pi/scripts/temp_control/logs/"$today".log | awk 'END{print}'`
function rightNow {
lastTemp=`echo $lastRecord | cut -d'-' -f2`
timeOfTemp=`echo $lastRecord | cut -d'-' -f1` # Not used yet
#Command used to update
sed -i "s/['Temp', [0-9]\{1,2\}.[0-9]\{1,3\}]/$lastTemp]/" /var/www/rightnow.html
}
rightNow
You cud get your file just like any other ajax request.
Using javascript
var request = new XMLHttpRequest();
request.open('GET', 'public_path_to_file.txt', false);
request.send();
var textFileContent = request.responseText
Using jQuery
var textFileContent;
$.get('public_path_to_file.txt', function(data) {
textFileContent = data;
});
Whats left is to get the right part from textFileContent. Dependent of the structure of the file we can do this in different ways. Without an example file you are on your own but here is some examples.
If you need the last line
var lines = textFileContent.split("\n");
var lastLine = lines[lines.length - 1];
If you need to use regex
var regex = //* some regex to get your content*//gm;
var result = regex.exec(textFileContent);
// result should now the content who matches your regex
First I'll assume that you ultimately want to read a local file with your browser and your current workflow is something like a local 'bash-script' that
first updates/modifies an inline piece of javascript (inside a locally stored html
file) with the last occurring value retrieved from a local txt-file (using sed)
opens the (just modified html-) file (via commandline) inside a common browser.
Then I assume the sed-route once worked but now doesn't work anymore (probably because the html file has changed?) and now you'd like the inline javascript (in the html file) to fetch that value from the textfile itself and subsequently use it (thus without the need for the 'bash-script'/sed solution.
Thus, the answer (based on above assumptions) to your final question: 'is there any javascript code that takes that file, extracts the last value and simply displays it on the right place of the code?', depends on your final requirement:
are you ok with a file-input where you select the text-file every time you view the html-file?
If your answer is YES, then, (depending on the browser you use) you can read a local file (and work your magic on it's contents).
In modern browsers, using the File API (which was added to the DOM in HTML5) it's now possible for web content to ask the user to select local files, then read the contents of those files.
For example, using FireFox's 'FileReader' you could do:
html:
<input type="file" id="fileinput" multiple />
javascript:
function readAllFiles(evt){
var files = evt.target.files, i = 0, r, f;
if(files){
for(; f = files[i++]; ){
r = new FileReader();
r.onload = (function(f){
return function(e){
alert(e.target.result);
};
})(f);
r.readAsText(f);
}
} else {
alert("Error loading files");
}
}
document.getElementById('fileinput')
.addEventListener('change', readAllFiles, false);
Note that for accessing local files in Chrome you must start Chrome with this switch: chrome --disable-web-security
However,
if the answer is NO (so you want to specify the file, and more importantly it's path, inside the 'code', so you don't have to select the text-file every time your local app runs) then you (usually) can't (because you can't get/set the path, thank the great maker)...
Unless you choose a specific older/unpatched browser (specifically for this task) where you know of a (hack) way to do this anyway (like the IE xml vulnerability or the XMLHTTP vulnerability or etc... you get the picture..).
Some alternative solutions (that don't require you to select the correct textfile over and over again)
Setup a fullblown web (LAMP) server (to use the XMLHttpRequest way as used in aross answer, but this might feel like shooting at a mosquito with a cannon..)
Explore different script languages (but effectively still do the same as your now broken sed-solution)
Combine 1 and 2, choosing from php (the latest version has a small webserver included, you might start/stop it when needed (even in the bash-script workflow) OR using node.js (which is 'javascript' and where you can program/control a small task-specific server in just a couple of lines).
Hope this helps!
Update:
Based on your updated question, comments and request for recommendation, I'd like to suggest to use PHP to dynamically fetch the value from your log txt file and have it generate your html code with inline javascript on the fly (every time you visit the page).
The browser will never see the php code, only what php inserted to your page (in this example the last found value or 0).
You'd rename the rightnow.html file to rightnow.php and modify it (something like) this:
<!DOCTYPE html>
<html><head>
<!-- your header code -->
<script type="text/javascript">
//parts of your javascript
<?php // start php script
$logFile= '/pathToYour/logFile.log'; // <-Modify
if( $fp= #fopen($logFile, "r") ){ // if logfile succesfully opened,
fseek($fp, -30, SEEK_END); // set pointer 30 chars from EOF
$val= array_pop(explode("-", rtrim(fread($fp, 30)))); //get last value
fclose($fp); // close file
}
?> // end php script
function drawChart(){
var data=google.visualization
.arrayToDataTable([ ['Label', 'Value'],
['Temp', <?php echo $val? $val : "0"; ?>],
]); // ^php above inserts value or 0
// etc...
}
//parts of your javascript
</script>
</head><body>
<!-- your body code -->
</body></html>
Note that fopen in combination with setting the filepointer via fseek and sequentially fread-ing from the pointer to EOF does not load the complete logfile (60min * 24hour=1440 lines of 16 bytes=22.5kB at the end of the day) into memory (good for this purpose), but only the last 30 chars (as in this example).
The variable to your logfile and path must still be modified to your situation (I don't know the format of your $today variable).
Depending on your further needs you might want to perform some extra checks/logic on the array of values that explode returns (instead of popping the last value). Or what about modifying the html a little so you could also include the last temperature's time reading, etc. (But this tested piece of code should get you started and explains the procedure of going the php way).
Update:
Since you have chosen to place the last known value of your logfile as in textfile placed inside your public www-root (with a bash script I assume, every minute of the day?), you can now indeed go the 'ajax' way, as answered by aross!
However I want to hint that the code/solutions in all current answers here could be mixed (since you now also have ajax working): instead of ajax-ing (loading) a txt file, you could have php fetch and send this value to the browser on-the-fly/on-demand!
So, instead of requesting http://url_to_my_rpi/file_to_download.txt, you could request http://url_to_my_rpi/read_last_temperature.PHP which should fetch the last known value out of the log-file (set proper security/access) and send it to the browser (set proper headers), just like your text-file did. You wouldn't have to change anything in the html/javascript except the url you request.
The advantage would be (depending on how your current bash-scripts works) that your PI now only does this 'work' (of getting the last value of your logfile) when you are viewing your monitor-page. And that you are not writing that file in your www-root every minute of every day (as I suspect).
The solution achieved, finally, was like this:
I did it with a jQuery statement and reusing the javascript code of Google Charts.
First I added javascript and jQuery tags in the html file:
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script type='text/javascript' src='https://www.google.com/jsapi'></script>
Then I merged jquery code and javascript code that I had in one script:
<script type='text/javascript'>
// Needed this var so that I could use it in other places of the code
var t;
jQuery.get('http://url_to_my_rpi/file_to_download.txt',function(data){
console.log(data)
t=data;
},'text');
google.load('visualization', '1', {packages:['gauge']});
google.setOnLoadCallback(drawChart);
function drawChart() {
t=eval(t);
var data = google.visualization.arrayToDataTable([
['Label', 'Value'],
['Temp', t],]);
// (... more javascript with Google Charts options, display parameters..)
</script>
Finally, and even if it's not listed as the main question, be sure to enable *mod_headers* on your apache and add Header set to apache2.conf file (In my case: /etc/apache2/apache2.conf)
1) Enable the module:
a2enmod headers
2) Add the line on your configuration file
Header set Access-Control-Allow-Origin "*"
3) Restart apache 2
4) In case the 3 steps above didn't work, follow the instrcutions by entering in this website or reinstall apache2.
I'm trying to read in a local text file to perform functions like counting syllables, characters etc.,
I am trying to do this by doing:
var txtFile = new XMLHttpRequest();
txtFile.open("GET", "file://path/to/my/file.txt", true);
txtFile.onreadystatechange = function() {
if (txtFile.readyState === 4) { // Makes sure the document is ready to parse.
if (txtFile.status === 200) { // Makes sure it's found the file.
allText = txtFile.responseText;
//lines = txtFile.responseText.split("\r\n"); // Will separate each line into an array
} //"\r\n"
}
}
when I try to log 'txtFile' to the command line it prints [ObjectHtmlRequest], how do i look at what i'm loading and consequently iterate over it?
I also get an error message when i try doing this piece of code
var text = txtFile
//$(this).val();
//document.text_input.my_text.value = newtext;
var words = new Array(text.replace(/\s/g, ' ').split(' '));
which worked before, but i'm guessing it's not now because i'm no longer working with text
Most browsers won't allow JavaScript to use the local filesystem. Chrome definitely won't, I'm not sure about Firefox and the others.
What I do in that case is either :
Use a local web server based on the local directory if the file you want to read is static. I usually start it with python -mhttp.server (Python 3) or python -mSimpleHTTPServer (Python 2).
Use the latest HTML5 File API if you want to let the user choose the file. More information here.
EDIT: Well, what I said isn't entirely true. Chrome allows you to use local files, but you have to start it on the command line with a special switch (--allow-file-access-from-files), and frankly, it's a bother and is only really intended for development. Don't rely on it for anything in production!
I'm trying to use NetUtil.asyncCopy to append data from one file to the end of another file from a Firefox extension. I have based this code upon a number of examples at https://developer.mozilla.org/en-US/docs/Code_snippets/File_I_O, particularly the 'Copy a stream to a file' example. Given what it says on that page, my code below:
Creates nsIFile objects for the file to copy from and file to append to and initialises these objects with the correct paths.
Creates an output stream to the output file.
Runs the NetUtil.asyncCopy function to copy between the file (which, I believe, behaves as an nsIInputStream) and the output stream.
I run this code as append_text_from_file("~/CopyFrom.txt", "~/AppendTo.txt");, but nothing gets copied across. The Appending Text and After ostream dumps appear on the console, but not the Done or Error dumps.
Does anyone have any idea what I'm doing wrong here? I'm fairly new to both Firefox extensions and javascript (although I am a fairly experienced programmer) - so I may be doing something really silly. If my entire approach is wrong then please let me know - I would have thought that this approach would allow me to append a file easily, and asynchronously, but it may not be possible for some reason that I don't know about.
function append_text_from_file(from_filename, to_filename) {
var from_file = Components.classes["#mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
from_file.initWithPath(from_filename);
var to_file = Components.classes["#mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
to_file.initWithPath(to_filename);
dump("Appending text\n");
var ostream = FileUtils.openFileOutputStream(to_file, FileUtils.MODE_WRONLY | FileUtils.MODE_APPEND)
dump("After ostream\n");
NetUtil.asyncCopy(from_file, ostream, function(aResult) {
dump("Done\n");
if (!Components.isSuccessCode(aResult)) {
// an error occurred!
dump(aResult);
dump("Error!\n")
}
});
}
asyncCopy() requires an input stream not a file.
you can do this:
var fstream = Cc["#mozilla.org/network/file-input-stream;1"].createInstance(Ci.nsIFileInputStream);
fstream.init(from_file, 0x01, 4, null);
NetUtil.asyncCopy(fstream, ostream, function(aResult)....
I am trying to find a way where by we can auto save a file in Firefox using JS. The way I have done till yet using FireShot on a Windows Desktop:
var element = content.document.createElement("FireShotDataElement");
element.setAttribute("Entire", EntirePage);
element.setAttribute("Action", Action);
element.setAttribute("Key", Key);
element.setAttribute("BASE64Content", "");
element.setAttribute("Data", Data);
element.setAttribute("Document", content.document);
if (typeof(CapturedFrameId) != "undefined")
element.setAttribute("CapturedFrameId", CapturedFrameId);
content.document.documentElement.appendChild(element);
var evt = content.document.createEvent("Events");
evt.initEvent("capturePageEvt", true, false);
element.dispatchEvent(evt);
But the issue is that it opens a dialog box to confirm the local drive location details. Is there a way I can hard code the local drive storage location and auto save the file?
If you are creating a Firefox add-on then FileUtils and NetUtil.asyncCopy are your friends:
Components.utils.import("resource://gre/modules/FileUtils.jsm");
Components.utils.import("resource://gre/modules/NetUtil.jsm");
var TEST_DATA = "this is a test string";
var source = Components.classes["#mozilla.org/io/string-input-stream;1"].
createInstance(Components.interfaces.nsIStringInputStream);
source.setData(TEST_DATA, TEST_DATA.length);
var file = new FileUtils.File("c:\\foo\\bar.txt");
var sink = file.openSafeFileOutputStream(file, FileUtils.MODE_WRONLY |
FileUtils.MODE_CREATE);
NetUtil.asyncCopy(source, sink);
This will asynchronously write the string this is a test string into the file c:\foo\bar.txt. Note that NetUtil.asyncCopy closes both streams automatically, you don't need to do it. However, you might want to pass a function as third parameter to this method - it will be called when the write operation is finished.
See also: Code snippets, writing to a file
Every computer has a different file structure. But still, there is a way. You can save it to cookie / session, depends on how "permanent" your data wants to be.
Do not consider writing a physical file as it requires extra permission.
I'm working on a project (BrowserIO - go to browserio dot googlecode dot com if you want to check out the code and work on it. Help welcome!) in which I'm using Firefox's nsIFileInputStream in tandem with nsIConverterInputStream, per their example (https://developer.mozilla.org/en/Code_snippets/File_I%2F%2FO#Simple), but only a portion of the full data is being loaded. The code is:
var file = Components.classes["#mozilla.org/file/local;1"].createInstance(Components.interfaces.nsILocalFile);
file.initWithPath(path);
var data = "";
var fstream = Components.classes["#mozilla.org/network/file-input-stream;1"].createInstance(Components.interfaces.nsIFileInputStream);
var cstream = Components.classes["#mozilla.org/intl/converter-input-stream;1"].createInstance(Components.interfaces.nsIConverterInputStream);
fstream.init(file, -1, 0, 0);
cstream.init(fstream, "UTF-8", 0, 0); // you can use another encoding here if you wish
var str = {};
cstream.readString(-1, str); // read the whole file and put it in str.value
data = str.value;
cstream.close(); // this closes fstream
If you want to see this behavior, checkout the code from the BrowserIO project page, and use Firebug to set a breakpoint at the data = str.value; line in file_io.js. Then select a text file from the list, and click the "Open" button. In Firebug, in the watch panel set a watch for str.value. Look at the file... It should be truncated, unless it's really short.
For reference, the code above is the main body of the openFile() function in trunk/scripts/file_io.js.
Anybody have any clue what's happening with this?
See nsIConverterInputStream; basically, -1 doesn't mean "give me everything" but rather "give me the default amount", which the docs claim is 8192.
More generally, if you want to exhaust the contents of an input stream, you have to loop until it's empty. Nothing in any of the stream contracts guarantees that the amount of data returned by a call is the entirety of the contents of the stream; it could even return less than it has immediately available if it wanted.
I discovered how to do the file read without converting, to avoid issues from not knowing the file encoding type. The answer is to use nsIScriptableInputStream with nsIFileInputStream:
var sstream = Components.classes["#mozilla.org/scriptableinputstream;1"].createInstance(Components.interfaces.nsIScriptableInputStream);
fstream.init(file, 0x01, 0004, 0);
sstream.init(fstream);
data = sstream.read(sstream.available());