I have a small .png file stored in Mongo using GridFS. I would like to display the image in my web browser using Node + Express + Jade. I can retrieve the image fine e.g.:
FileRepository.prototype.getFile = function(callback,id) {
this.gs = new GridStore(this.db,id, 'r');
this.gs.open(callback);
};
but I don't know how to render it using the Jade View Engine. There doesn't seem to be any
information in the documentation.
Can anyone point me in the right direction?
Thanks!
I figured this out (thanks Timothy!). The problem was my understanding of all these technologies and how they fit together. For anyone else who's interested in displaying images from MongoDB GridFS using Node, Express and Jade ...
My Document in MongoDB has a reference to the Image stored in GridFS which is an ObjectId stored as
a string. e.g. MyEntity {ImageId:'4f6d39ab519b481eb4a5cf52'} <-- NB: String representation of ObjectId. The reason I stored it as a string was because storing the ObjectId was giving me a pain
in the Routing as it was rendering as binary and I couldn't figure out how to fix this. (Maybe someone can help here?). Anyway, the solution I have is below:
FileRepository - Retrieve the image from GridFS, I pass in a String Id, which I then convert to
a BSON ObjectId (you can also get the file by file name):
FileRepository.prototype.getFile = function(callback,id) {
var gs = new GridStore(this.db,new ObjectID(id), 'r');
gs.open(function(err,gs){
gs.read(callback);
});
};
Jade Template - Render the HTML Markup:
img(src='/data/#{myentity.ImageId}')
App.JS file - Routing (using Express) I setup the '/data/:imgtag' route for dynamic images:
app.get('/data/:imgtag', function(req, res) {
fileRepository.getFile( function(error,data) {
res.writeHead('200', {'Content-Type': 'image/png'});
res.end(data,'binary');
}, req.params.imgtag );
});
And that did the job. Any questions let me know :)
I'm a little confused about what you're trying to do here, as Jade is a condesed markup language for text output (such as HTML), not binary content.
Since you're using Jade you probably have something like this:
app.get/'images/:imgtag', function(req, res) {
res.render('image', {imgtag: req.params.imgtag);
});
So try this:
app.get/'images/:imgtag', function(req, res) {
filerep.getFile( function(imgdata) {
res.header({'Content_type': 'image/jpeg'})
res.end(imgdata);
}, req.params.imgtag );
});
That will send the raw file as a response to the HTTP request with the correct mime type. If you want to use Jade to deliver a template (such as an image popup) you could use a different route for the popup or even use a data: uri and encode the image data in the page.
Related
Is it possible to fetch data from MongoDB and render a html template on the server side itself for a node-js project?
As of now in my serverside js file I've done the following.
//Failing array will be populated by a db.find later on.
var failing = [
{ name: "Pop" },
{ name: "BOB" }
];
/*Now i have to send a mail from the server for which I'm using nodemailer.
Where do i store the template ? This is what I've done in the same file */
var template = "<body>{#failing} <p>{.name}</p> {/failing}</body>"
// Add this as the body of the mail and send it.
I'm not sure how to render the data and how to get it displayed. I'm aware storing the template in the variable isn't right but I'm not sure what else to do.
If your template is that short, you can store it in a variable without problem. Obviously, you can store it in a file also.
Let's say you decide to store it in a file index.dust:
<body>{#failing} <p>{.name}</p> {/failing}</body>
Now, in your node controller you need to load the file and generate the html content from it:
const fs = require('fs');
const dust = require('dustjs-linkedin');
// Read the template
var src = fs.readFileSync('<rest_of_path>/index.dust', 'utf8');
// Compile and load it. Note that we give it the index name.
var compiled = dust.compile(src, 'index');
dust.loadSource(compiled);
// Render the template with the context. Take into account that this is
// an async function
dust.render('index', { failing: failing }, function(err, html) {
// In html you have the generated html.
console.log(html);
});
Check the documentation in order not to have to compile the template every time you have to use it.
I want to convert some html page to pdf via wkhtmltopdf. However, the html page I want to convert to pdf is dynamically generated using handlebars.
So I think one solution maybe to generate the html page via handlebars but to a file (html file). Then, convert that file to pdf using hkhtmltopdf, then allow the user to, somehow, download the pdf.
So, my question is: how can I render the (handlebars) dynamically generated html page to a file?
Thanks and bye ...
Simple example for create file.
var Handlebars = require('handlebars');
var source = "<p>Hello, my name is {{name}}. I am from {{hometown}}. I have " +
"{{kids.length}} kids:</p>" +
"<ul>{{#kids}}<li>{{name}} is {{age}}</li>{{/kids}}</ul>";
var template = Handlebars.compile(source);
var data = { "name": "Alan", "hometown": "Somewhere, TX",
"kids": [{"name": "Jimmy", "age": "12"}, {"name": "Sally", "age": "4"}]};
var result = template(data);
var fs = require('fs');
fs.writeFile("test.html", result, function(err) {
if(err) {
return console.log(err);
}
});
Using express-handlebars, you should use the advanced mode and create an instance of it like in this example.
The proper way would be to create a view file (like you probably already have per you question) and use the express handlebars instance to render it:
// init code
var exphbs = require('express-handlebars');
var hbs = exphbs.create({
defaultLayout: 'your-layout-name',
helpers: require("path-to-your-helpers-if-any"),
});
app.engine('.file-extention-you-use', hbs.engine);
app.set('view engine', '.file-extention-you-use');
// ...then, in the router
hbs.render('full-path-to-view',conext, options).then(function(hbsTemplate){
// hbsTemplate contains the rendered html, do something with it...
});
HTH
Code above from Alex works perfect. However, my confusion was: I was using 'express-handlebars' and not 'handlebars'. Now, what I can understand is Express-Handlebars is an implementation of Handlebars for an Express application, which I´m using. I just didn't find a way to use the 'compile()' method in Express-Handlebars, so I ended up installing Handlebars (standalone) and used it to compile my (html) template and save the result to disk, just as Alex explained above.
In summary:
1) I know Express-Handlebars is Handlebars for Express app.
2) I don't know how to use "compile()" method just from express-handlebars, so I ended up installing Handlebars (from npm) and using it on the server to produce my html file (from template) and save it to disk.
3) Of course I installed and use Express-Handlebars everywhere to serve my pages in my Express app; just installed Handlebars to produce my html (in the server) with "compile()" method and save the result to disk.
Hope this is understandable. Thanks again and bye ...
I'm having a small issue with rendering HTML, stored in CouchBase, fetched by Node.js
In CouchBase I have several small HTML-snippets. They contain text, tags such as <br /> and html entities such as <. They are of course stored as an escaped string in JSON.
So far, so good. However when I pull it out and display on the page, it is rendered "as-is", without being interpreted as HTML.
For example:
[ some content ...]
<p>Lorem is > ipsum<br />And another line</p>
[rest of content ...]
From the controller in Express 4:
var express = require('express');
var router = express.Router();
var couchbase = require('couchbase');
var cluster = new couchbase.Cluster('couchbase://myserver');
var bucket = cluster.openBucket('someBucket', 'somePassword');
var Entities = require('html-entities').XmlEntities;
entities = new Entities();
var utf8 = require('utf8');
/* GET home page. */
router.get('/', function(req, res) {
bucket.get('my:thingie:44', function(err, result) {
if(err) throw err
console.log(result);
var html = utf8.decode(entities.decode(result.value.thingie.html));
// var html = utf8.encode(result.value.thingie.html);
// var html = utf8.decode(result.value.thingie.html);
res.render('index', { title: 'PageTitle', content: html });
});
});
It is then passed to the template (using hogan.js) for rendering.
When looking into this I found that it might have something to do with the encoding of the <'s and <'s that prevent it from being parsed. You can see my converting attempts in the code, where none of the options gave the desired result, i.e. rendering the contents as HTML.
When using utf8.decode(), no difference.
Using utf8.encode(), no difference.
Using entities.decode() it convert < into < as predicted, but it's not rendered even if <div;> becomes <div>.
Any ideas?
I found the solution over here: Partials with Node.js + Express + Hogan.js
When putting HTML in a Hogan template, you have to use {{{var}}} instead of {{var}}.
And thus it renders beautifully, as intended :)
Wasn't encoding issues at all ;)
I have some data in a mongodb database and want to pass it to a backbone collection when I load the home page. One way of doing this would be to set up a node route like this:
exports.index = function(req, res){
db.users.find(function(err, docs) {
var docs_string = JSON.stringify(docs);
res.send(docs_string);
};
};
But this won't work because it won't render my jade template that pulls in the backbone code, it simply shows the JSON in plain text.
Alternatively, I could render my jade template passing in the data as a variable to jade:
exports.index = function(req, res){
db.users.find(function(err, docs) {
var docs_string = JSON.stringify(docs);
res.render('index', {
title: "Data",
docs_string: docs_string
})
});
};
Then in the jade template, have a script like this to add the users to my user collection:
script
var docs = !{docs_string};
var users = new app.Users();
_.each(docs, function(doc) {
var user = new app.User(doc);
users.add(user);
})
But this seems wrong, since I don't really want to pass the data to the jade template, I want to pass it to a backbone collection. Also, with this solution I don't know how to then include an underscore template (on the backbone side of things) into the page rendered by jade on the server side.
What is the standard way of passing data from a node server to a backbone collection?
Assuming your data is an object, you should convert it to string using JSON.stringify() and then insert in a page inside script tag, so your resulting HTML looks like this (I don't use Jade):
<script>
var data = {...}; // in template instead of {...} here should be the instruction to insert your json string
</script>
Then when the page loads, your script will be executed and the data will be available as a global variable in the browser so you can initialise backbone collection using it. This all is a good idea only to bootstrap your data on the first page load (to avoid extra request) and then use API to request data for this and other pages.
Check out Steamer, a tiny node / express module made for this exact purpose.
https://github.com/rotundasoftware/steamer
Using Express.js, I'd like to render a partial-view from a Jade template to a variable.
Usually, you render a partial-view directly to the response object:
response.partial('templatePath', {a:1, b:2, c:3})
However, since I'm inside a Socket.io server event, I don't have the "response" object.
Is there an elegant way to render a Jade partial-view to a variable without using the response object?
Here's the straight solution to this problem for express 3 users (which should be widely spread now):
res.partial() has been removed but you can always use app.render() using the callback function, if the response object is not part of the current context like in Liors case:
app.render('templatePath', {
a: 1,
b: 2,
c: 3
},function(err,html) {
console.log('html',html);
// your handling of the rendered html output goes here
});
Since app.render() is a function of the express app object it's naturally aware of the configured template engine and other settings. It behaves the same way as the specific res.render() on app.get() or other express request events.
See also:
http://expressjs.com/api.html#app.render for app.render()
https://github.com/visionmedia/express/wiki/Migrating-from-2.x-to-3.x for express 2.x > 3.x migration purposes
You can manually compile the Jade template.
var jade = require('jade');
var template = require('fs').readFileSync(pathToTemplate, 'utf8');
var jadeFn = jade.compile(template, { filename: pathToTemplate, pretty: true });
var renderedTemplate = jadeFn({data: 1, hello: 'world'});