I am trying to develop an app for Ubuntu Touch. I am using QML integrated with JavaScript.
I know that it is a huge mess to read or write to files in JavaScript when it is embedded in a webpage, but this is not embedded in a webpage so it should be easier right? The Ubuntu documentation is pretty bad right now.
Does anyone know how I can get this done? I want to get it done without using c++ because using QML, JavaScript and c++ seems like just a big mess. If the only way to do it is using c++ then I guess thats what I will have to do, but I would like to find another way.
You will have to write a wrapper for QFile class that will be exposed to QML code. Here is an example how to do that. I'm not sure if it's outdated but it looks like it should work just fine.
The simplest way to handle data in your Ubuntu Touch app is to actually use SQLite (No surprise there). You can find a really good tutorial on using SQLite with Ubuntu Touch here:
https://askubuntu.com/questions/352157/how-to-use-a-sqlite-database-from-qml
It seems like this is the most efficient way to handle app data in Ubuntu Touch. If you want to be able to write to an actual file, you need to handle it using c++. Check out Kamil's answer for that.
Related
I am working on a sentiment analysis project, where the backbone is ofc a model. This was developed using sklearn's off the shelf solutions (MLP) trained with my data. I would like to "save" this model and use it again in JavaScript.
Adam
I have looked at pickle for python but I'm not sure how i could use this for JS. This is a chrome extension I am developing so I would rather not set up and server. I should add this is course work, so spending money is a no!
After some research I pretty much determined its not possible using sklearn in JS. My solution was to use keras and use tensorflow JS.
Alternatively, I have learnt the maths behind the network and "raw" code it using no libraries. This took a lot longer than just converting everything to keras although.
I am currently evaluating different approaches / solutions to call C++ functions from JavaScript code embedded in an HTML page. The application must be run on Ubuntu Server 12.04 LTS.
I am not an expert in Linux based development. This is the first time I am trying to work on something to interface between JavaScript and C++ code.
The C++ code basically resides in the .so files ( dynamic libraries) that would provide interface methods to access certain hardware and file system. The GUI needs to be in HTML and I am searching for different solutions that are possible that can call C++ from HTML. I searched and ended up deciding to try 2 approaches, both using the WebKit engine.
Approach 1: Using Qt 5.0.2 Webkit Bridge - the WebView control
The GUI framework will be on Qt framework, the main application window will contain a webview control that would run an HTML code which in turn contains the JavaScript code.
The interface between Web page and C++ is done using the addToJavaScriptWindowObject() function.
I created a sample application and tested this solution and it seems to works fine.
Approach 2: Using GTK+ WebKit WebView
I downloaded and installed the GTK 3.0 library.
I got the webkitgtk 2.0.1 and have installed it.
I have created a test application with GTK without webkit, it works well.
I am trying to create a webkit webview control using GTK.
When trying my Approach 1 with Qt, there was quite a good set of documentation and samples to do what I wanted to. But after starting with Approach 2 using GTK+, I feel am moving slower comparitively. I personally feel that the documentation part is not that straight forward for the kind of application I am trying to develop.
Other Approaches:
I also want to try to check if either using Applets (to call the .so files directly) or using the V8 JavaScript engine to interface between JavaScript and C++ are viable options(https://code.google.com/p/v8/)
I have tried the following resources:
http://webkitgtk.org/
http://www.webkit.org/
https://live.gnome.org/WebKitGtk/ProgrammingGuide/Tutorial
I want to know how exactly to do this interface part of calling a C++ functions (in .so files) when a button is clicked in a HTML web page containing JavaScript. What kind of signal am I supposed to look for. If I am using a WebkitWebview control, how do I map a button click to a c++ function?
Can someone point me to the right direction?
I would really appreciate your time and knowledge.
Regards.
Webkit GTK 2 changed significantly in terms of API's. So I am not sure if this will work with Webkit GTK 2. However this will definitely work in Webkit GTK 1.* versions. Don't know anything about QT.
For your need of connecting html view with C/C++ side of the world, you can use two approaches. Please take a look at function webkit_dom_event_target_add_event_listener. There is example at https://live.gnome.org/WebKitGtk/ProgrammingGuide/Cookbook
Another approach you can take is to use alert on click of the button and send a string as information. On C side, you can hookup the alert listener and parse the message and decide what needs to be done. I have written lot of code in python which takes this approach since call mentioned above is not exposed to python.
I agree documentation is bit sparse for webkit gtk. However if you know how you can acomplish something in javascript, usually you can map the javascript DOM management and event calls to C side. This includes generating elements dynamically, managing events such onclick etc. You just have to dig through the header files and find matching call.
If you need to use C++ code or native applications in your web application you can try to create a service over the C++ code and access it throught a REST (for example) API.
You can use a common web application framework (Spring/Java, Django/Python, etc.) to develop your web application and use Apache Thrift to interface your library.
the best solution for you is g-xml it is a good solution by GAMA but sorry it is not free.
This is part of a project I am working on for work.
I want to automate a Sharepoint site, specifically to pull data out of a database that I and my coworkers only have front-end access to.
I FINALLY managed to get mechanize (in python) to accomplish this using Python-NTLM, and by patching part of it's source code to fix a reoccurring error.
Now, I am at what I would hope is my final roadblock: Part of the form I need to submit seems to be output of a JavaScript function :| and lo and behold... Mechanize does not support javascript. I don't want to emulate the javascript functionality myself in python because I would ideally like a reusable solution...
So, does anyone know how I could evaluate the javascript on the local html I download from sharepoint? I just want to run the javascript somehow (to complete the loading of the page), but without a browser.
I have already looked into selenium, but it's pretty slow for the amount of work I need to get done... I am currently looking into PyV8 to try and evaluate the javascript myself... but surely there must be an app or library (or anything) that can do this??
Well, in the end I came down to the following possible solutions:
Run Chrome headless and collect the html output (thanks to koenp for the link!)
Run PhantomJS, a headless browser with a javascript api
Run HTMLUnit; same thing but for Java
Use Ghost.py, a python-based headless browser (that I haven't seen suggested anyyyywhere for some reason!)
Write a DOM-based javascript interpreter based on Pyv8 (Google v8 javascript engine) and add this to my current "half-solution" with mechanize.
For now, I have decided to use either use Ghost.py or my own modification of the PySide/PyQT Webkit (how ghost works) to evaluate the javascript, as apparently they can run quite fast if you optimize them to not download images and disable the GUI.
Hopefully others will find this list useful!
Well you will need something that both understands the DOM and understand Javascript, so that comes down to a headless browser of some sort. Maybe you can take a look at the selenium webdriver, but I guess you already did that. I don't hink there is an easy way of doing this without running the stuff in an actually browser engine.
I would like to setup a simple web browser that download a html page , parse it, generate a dom and execute the javascript code. I would like to know if there is a simple project(so not firefox which is good but too big to just understand this piece of logic) showing if it is the right way to handle this or someone to explain me if i am missing something. No particular language( but preferably be python, c#/c++/c ). I am stuck now at integrating the javascript engine, i don't know what to do.
Thx
I don't think its easy to pull off a javascript engine on your own. You could however use an open source engine (like WebKit's JS engine for example) and integrate it in your project.
More Infos:
http://www.webkit.org
google chrome is open source too with a neat javascript engine v8.
http://code.google.com/chromium/
http://code.google.com/p/v8/
another way could be nodejs. it's server side javascript using the v8 engine. so there is no rendering, just pure javascript. maybe thats enough if you do not need the rendering.
http://nodejs.org/
You might want to use the WebBrowser class from .NET for that purpose.
http://msdn.microsoft.com/en-us/library/system.windows.forms.webbrowser.aspx
I'm trying to scrape and submit information to websites that heavily rely on Javascript to do most of its actions. The website won't even work when i disable Javascript in my browser.
I've searched for some solutions on Google and SO and there was someone who suggested i should reverse engineer the Javascript, but i have no idea how to do that.
So far i've been using Mechanize and it works on websites that don't require Javascript.
Is there any way to access websites that use Javascript by using urllib2 or something similar?
I'm also willing to learn Javascript, if that's what it takes.
I wrote a small tutorial on this subject, this might help:
http://koaning.io.s3-website.eu-west-2.amazonaws.com/dynamic-scraping-with-python.html
Basically what you do is you have the selenium library pretend that it is a firefox browser, the browser will wait until all javascript has loaded before it continues passing you the html string. Once you have this string, you can then parse it with beautifulsoup.
I've had exactly the same problem. It is not simple at all, but I finally found a great solution, using PyQt4.QtWebKit.
You will find the explanations on this webpage : http://blog.motane.lu/2009/07/07/downloading-a-pages-content-with-python-and-webkit/
I've tested it, I currently use it, and that's great !
Its great advantage is that it can run on a server, only using X, without a graphic environment.
You should look into using Ghost, a Python library that wraps the PyQt4 + WebKit hack.
This makes g the WebKit client:
import ghost
g = ghost.Ghost()
You can grab a page with g.open(url) and then g.content will evaluate to the document in its current state.
Ghost has other cool features, like injecting JS and some form filling methods, and you can pass the resulting document to BeautifulSoup and so on: soup = bs4.BeautifulSoup(g.content).
So far, Ghost is the only thing I've found that makes this kind of thing easy in Python. The only limitation I've come across is that you can't easily create more than one instance of the client object, ghost.Ghost, but you could work around that.
Check out crowbar. I haven't had any experience with it, but I was curious about the answer to your question so I started googling around. I'd like to know if this works out for you.
http://grep.codeconsult.ch/2007/02/24/crowbar-scrape-javascript-generated-pages-via-gecko-and-rest/
Maybe you could use Selenium Webdriver, which has python bindings I believe. I think it's mainly used as a tool for testing websites, but I guess it should be usable for scraping too.
I would actually suggest using Selenium. Its mainly designed for testing Web-Applications from a "user perspective however it is basically a "FireFox" driver. I've actually used it for this purpose ... although I was scraping an dynamic AJAX webpage. As long as the Javascript form has a recognizable "Anchor Text" that Selenium can "click" everything should sort itself out.
Hope that helps