Using JS Charting Libraries with NodeJS - javascript

I've got a question regarding JavaScript charting libraries (Flot Charts, to be more specific).
At the moment, every library I've come across requires an HTML document in order to work (where the chart/graph would be constructed, in a canvas element, for example), but my problem is that I'm not creating a traditional web-page/application that requires an .html document, I'm creating a bot.
The reason I'm using the chart library is to generate an image that the bot can render to the user. In order to generate the graphic, do I need to create some generic html page where I can generate the graphic and then grab it and store it with JavaScript in my NodeJS project? Or perhaps there's something that I'm missing entirely.
Any and all help is really appreciated. Thanks a lot

Since Javascript runs on the client and node runs on the server, you're going to have a hard time getting the server to save a snapshot of your generated graphic. That's typically done on the server side of things.
I would switch your library to Plotly (http://plot.ly) and utilize it's Static Image Export feature:
https://plot.ly/nodejs/static-image-export/

Related

What is the simplest way of receiving and then processing a csv on a website?

Essentially I built an application using Python (specifically Pandas) that reads a csv then performs some actions on it then ultimately produces an output graph.
I wanted to make this application into a website and I have learnt a bit of HTML, CSS and JavaScript to do this. I want the website to mainly do these 2 things
Receive a file
Process the file using Python then output the image back to the website
What is the best course of action for this problem? Learn Flask? Learn Django? Would I need to learn anything else?
I've already learnt how to create a file uploader for the website using Vue but can't seem to wrap my head around connecting it to a database.
The simplest, leanest solution to just receive data and reply would be to start a http.server, see: https://docs.python.org/3/library/http.server.html. Anything else will be extra overhead, both in terms of learning and running. On the other hand, if this application will grow, learning Flask or Django will have added benefits.
Here I found a quick introductory tutorial on http.server: https://www.afternerd.com/blog/python-http-server/
For uploading, take a look at do_POST (e.g. here https://pymotw.com/3/http.server/) and look how to handle multipart form uploads (e.g. full example here https://gist.github.com/rctay/25bed284cd4bcc1477f4)

Are there any reporting library in Javascript/Angular.js?

I want to generate some reports in a MEAN.js Application, that said, i manage the data in Angular, what i want to know is if there's a library to generate a PDF Report, for example, when using PHP there's dompdf, fpdf, etc...
Basically what i need to generate is something like this from Angular:
Are there any tool to generate the reports from Angular, or should i generate them from Node.js? if so what are the tools available for node.js?
I only know about jsreport for node.js
Server-side rendering with Node is definitely the way to go, the client side libraries never really worked well (I last checked about a year ago). I'd suggest using PhantomJS as it provides PDF rendering capabilities out of the box.
PhantomJS will use Webkit engine to generate the PDF for you. The actual rendering process is dead simple:
page.render('/tmp/file.pdf', function() {
// file is now written to disk
});
Of course you have to insert something on the page you're generating first. Check out the following post which describes one guy's implementation, the code quoted above comes from there: http://www.feedhenry.com/server-side-pdf-generation-node-js/

Export a PDF report with charts from Node/Express/Angular/PhantomJS

I am using AngularJS in a MEAN stack based on DaftMonk’s generator (https://github.com/DaftMonk/generator-angular-fullstack). I am fairly new to pretty much everything Angular/JS/Node (and stackoverflow so please feel free to point out if I need to reword my question!).
I am aiming to produce a multipage PDF report for a user from an Angular page that contains six graphs, images and text.
There are a number of questions on stackoverflow and Google that relate to potential solutions to this, but having checked these exhaustively, they do not help with what I need to achieve (or I do not understand how I can use them in my scenario..).
Currently, when the user navigates to the ‘report page’, an http request is sent to Node/Express from the Angular controller, which checks the user role/group ID, queries the database, anaylses the data and sends it back to the browser for rendering into graphs (currently using angular-chartjs and flot).
The user selects graph type and can choose a maximum of six graphs to display from a possible list of 20+. These six graphs are what need to be exported to a PDF report (with other information). I need to make this (within reason) as browser compatible as possible (at least IE8+) although my current solution is IE10+ with PDF export disabled for older browsers using Modernizr.
From stackoverflow and Google, possible solutions include using PhantomJS in Node to capture the screen or using a client-side PDF renderer (e.g. jsPDF). Out of these, my feeling is that PhantomJS would provide the most flexibility/browser compatibility. Also, I need to produce several different reports depending on the user role, so having all the code to produce the reports within the browser is not desirable. But I am totally stuck as to how to access ‘what the client sees’ using the MEAN stack. PhantomJS would need to effectively be logged in as the client, and have access to the six choices for graphs that the client has made.
From my research, using PhantomJS would require creating an html page, somehow transferring what the client sees/data/graph choices to it, and then capturing that to render to a PDF, before sending back to the browser. One way might be to pass the required information back to Express (with a POST?) and then rendering a server-side html page which PhantomJS could be pointed to, but I have no idea how to achieve this (or if it's possible). Another possibility would be to store the client report data, choices, etc in the database and set off a task to render the PDF and send it back to the browser when done, but again, I have no idea how to achieve this.
I have read about cookies in PhantomJS or navigating through the login page using code, but this seems to be a cumbersome way to achieve this. Can an html file be created server-side, with chart.js (or another charting library) injected (and angular?) and all the required user data/chart choices for PhantomJS to render to a PDF? I guess in some ways I need to be able to use a PDF generator, charting library, etc server-side to create a PDF.
Any advice (with possible code examples) on how to achieve this would be appreciated.
I guess I had the same problem as you (only I was using Laravel in server side).
The idea I came up with was to convert the canvas generated by angular-chartjs to images (using toDataURL() on the canvas elements)
$('.theCanvas').each(function () {
var canvas=this;
img=JSON.stringify(canvas.toDataURL());
});
http://plnkr.co/edit/PkZiqYynzQXehbe6p1eH?p=preview
and then sending the images to the server to create the pdf , and finally sending the user the link to the created PDF.
In my case, they are plenty of packages to generate a PDF from an html in server side, and I don't know if a tool exists for Node.
I hope this helps.

Processing Javascript on the server

I'm looking to use this chart generation library: http://www.jqchart.com/
Ideally, I would prefer to use a PHP charting library for the current project I'm working, but, by the looks of it, this is the only library I've found that can handle what I need to do (given a somewhat unconventional requirement for the charts).
The issue is that I need to get the generated graphs as images (at the moment each graph seems to be a combination of images) to the server so that I can generate some PDF documents, etc.
I'm thinking of attempting to create an image using JS, pushing this back to the server and then generating the PDF although this pretty nasty and will probably cause issues between different versions of the browser.
So now what I'm looking for is a solution that will allow me to generate the graphs and turn them into images on the backend.
Any ideas?
EDIT: For the requirement that led me to rule out a number of other charting libraries, see here: Complex charts in Google Charts
That really isn't all that relevant to the question of processing Javascript on the server, though.
You can render a javascript graph on the server using phantomjs. Here is an example.
Not sure what your requirements are, but I'd check out Google Chart Tools: http://code.google.com/apis/chart/. It's really simple to use. All the data is in the image URL get request, so you can generate charts using client-side JavaScript too.

Run Flot, Javascript on Server?

I would like to use a Javascript library (Flot) to generate charts in my application. Most of the time, the charting will be performed by clients. However, I can see that in some cases, where the same charts would be frequently accessed by all clients, it would be better to generate those charts on the server, cache them, and serve them as images.
How could I go about executing Javascript from a script that runs on the server? Can Flot be used to generate PNG's?
This should be possible with Node.js and node-canvas. Node-Canvas can spit out PNGs for your cached graphs.

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