I have a nodejs app with Angular for the front-end stuff. I make a post call from the client side that saves a large JSON string in a collection in mongodb. I want the server side to then chop up the data and save it in the desired format in another collection. I cannot post correctly formatted data directly from the browser because that would mean making too many async post calls from the client side. Here is the code to post that big JSON string:
var request = $http({
method: "post",
url: "/students",
data: {
studentData: jsonData
}
}).then(function successCallback(response) {
}, function errorCallback(response) {
console.log(response);
});
I am not sure how to proceed from here. I am new to nodejs and am not sure how the server side code works. Is it handled in the server.js file? If so, is it feasible to do what I have described above?
This is what I understood after reading the whole thing. You have a big chunk of JSON data firstly you want to store it in collection 1 and then you want to perform some operation on it and then save the new refined data in some other collection 2.
I am going to give my answer based upon that.
To use Mongo we have various modules available for node js. Let's take mongoose as an example here, although you can use any because the concept remains the same as it is very simple.
After every insert entry to the mongodb using respective module you'll have a callback with data inserted. You can manipulate it and then make one more save operation in another collection.
Related
I'm sorry but I have been trying to solve this problem for 2 hours now. I am writing a small web app using nextjs. I load a csv file, send it to my backend via an API POST request and process it there. The processed data is then sent back to the frontend (an array of about 150 objects with 9 attributes each). Now I want the frontend to take the data and forward it to a new page (the "view" page should just be a different one from the one where I read it in). I just can't seem to do that. There was Router.query in nextjs 12, but it was abolished and I can't think of a meaningful way to transmit my data. Simply stringifying it and appending it as a query parameter doesn't work (probably because it's too long). I can't have the "view" page send a GET request because I don't want to store the data in the backend and it wouldn't be available for such a query. Can someone enlighten me?
const response = await fetch("/api/processcsv", {
method: "POST",
body: JSON.stringify(formData)
})
if (response.ok) {
console.log("Data send")
const res = await response.json()
router.push('/datadisplay?data='+JSON.stringify(res))
} else {console.log(response.status)}
not working
I'm trying to make an app using phonegap, but what I want to know is if it is possible to store information online. For example, say there is a number variable, and it is added to when a button is pushed. Could that value be saved somewhere and then a totally different device can retrieve the variable?
I looked at databases, but I couldn't really understand it. I want something that can be accessed by any device as long as It has a key or something.
Is this possible? If so, how would I do it?
PhoneGap uses JS so you cannot connect to the database directly. You should create a Web service using server side languages like PHP on external server and make ajax request on your web service. This approach is possible using PhoneGap.
Sample Code will look somewhere near:
function FetchData() {
$.ajax({
async: false,
type: "GET",
url: "Your_WebService_URL",
dataType: "json",
success: function(data) {
$.each(data, function(i, object) {
if(i==="title"){
document.getElementById("title").InnerHTML = object;
}
if(i==="home_image"){
document.getElementById("title").InnerHTML = '<img src="'+object+'"/>';
}
});
},
error: function() {
alert("There was an error loading the feed");
}
});
The web service, in this case json will throw the variables. May me somewhere like this :
[{"title":"my application"},{"home_image":"http://link.com/image.png"}]
I think this article is useful to you: Loading external data into a PhoneGap app using the jQuery JSONP plugin for cross-domain access. Also see this similar question here:
This is entirely possible.
You essentially need two components: the client interface, and the server.
The client displays the results to the users, and, using your example, waits for a button to be pushed. On the push of that button, the client would send a request to the server to increment the stored value (possibly through a jQuery.post, or get, function call).
The server page, written in php for example, receives this request, and accesses a file, or more realistically a database, to increment the value.
With some Googling, this should be very doable, but post specific questions if you get stuck.
We are building a service that exposes a REST Api to the clients and we are using jugglingdb to create the models and express as the server.. I was wondering if there are any modules that are useful when creating a RESTful API in node.js
I tried using restify but it seemed to be just a watered down version of express and seemed to lack some functionality i needed from express, so i switched to express.
EDIT: We have no front-end. So we are strictly a rest api service that just provides data for various clients
One approach to consider is to keep things light and simple. If you don't have a front end, you can use the Connect module alone instead of Express, which is built on Connect:
http://www.senchalabs.org/connect/
I had good luck with this approach with my Node.js RESTful API. I did end up with a few repeated patters, especially in parsing incoming post data at times. But I found the code snips were just too small to be worth putting into a module, and it offered me amazing flexibility in certain situations.
One more approach that worked very well for me: Post ALL of your data as JSON - not as post key/value pairs. Depending on your API's clients, you may be able to do this. My API client was jQuery AJAX calls from a web page. It's very easy to send a JSON post. The jQuery processData property allows this as follows:
$.ajax({
url: '/nodeAjaxHandler',
type: 'POST',
data: JSON.stringify(formVals),
processData: false,
dataType: 'json',
success: function(data) {
},
error: function(a, b, c) {
}
});
Now receiving the data in your Node server is as simple as waiting for the body text to load, then JSON.parse it into an object. Very readable and manageable. And when you change the data fields being posted and received, you don't need to change any of the interface code at all!
(And you can go one step further if you dare, and make the field names match your database field names - then you can consolidate even more code. This felt risky to me but worked brilliantly - I'm not sure what the down sides might be yet. I do escape all my field names as well as my column names in the mySQL queries.)
RESTfull API get and post data through HTTP protocol. A more progressive approach is to use WebSocket [Wikipedia] npm link. Try to play with Sails.js framework build on Express.js that use Socket.IO for flash data transfering
If you're using MongoDB (with mongoose):
http://benaugarten.com/node-restful/
https://npmjs.org/package/node-restful
I'm currently researching how to add persistence to a realtime twitter json feed in node.
I've got my stream setup, it's broadcasting to the client, but how do i go about storing this data in a json database such as couchdb, so i can access the stores json when the client first visits the page?
I can't seem to get my head around couchdb.
var array = {
"tweet_id": tweet.id,
"screen_name": tweet.user.screen_name,
"text" : tweet.text,
"profile_image_url" : tweet.user.profile_image_url
};
db.saveDoc('tweet', strencode(array), function(er, ok) {
if (er) throw new Error(JSON.stringify(er));
util.puts('Saved my first doc to the couch!');
});
db.allDocs(function(er, doc) {
if (er) throw new Error(JSON.stringify(er));
//client.send(JSON.stringify(doc));
console.log(JSON.stringify(doc));
util.puts('Fetched my new doc from couch:');
});
These are the two snippets i'm using to try and save / retrieve tweet data. The array is one individual tweet, and needs to be saved to couch each time a new tweet is received.
I don't understand the id part of saveDoc - when i make it unique, db.allDocs only lists ID's and not the content of each doc in the database - and when it's not unique, it fails after the first db entry.
Can someone kindly explain the correct way to save and retrieve this type of json data to couchdb?
I basically want to to load the entire database when the client first views the page. (The database will have less than 100 entries)
Cheers.
You need to insert the documents in the database. You can do this by inserting the JSON that comes from the twitter API or you can insert one status at a time (for loop)
You should create a view that exposes that information. If you saved the JSON directly from Twitter you are going to need to emit several times in your map function
There operations (ingestion and querying) are not the same thing, so you should really do them at the different times in your program.
You should consider running a bg process (maybe in something as simple as a setInterval) that updates your database. Or you can use something like clarinet (http://github.com/dscape/clarinet) to parse the Twitter streaming API directly.
I'm the author of nano, and here is one of the tests that does most of what you need:
https://github.com/dscape/nano/blob/master/tests/view/query.js
For the actual query semantics and for you learn a bit more of how CouchDB works I would suggest you read:
http://guide.couchdb.org/editions/1/en/index.html
I you find it useful I would suggest you buy the book :)
If you want to use a module to interact with CouchDB I would suggest cradle or nano.
You can also use the default http module you find in Node.js to make requests to CouchDB. The down-side is that the default http module tends to be a little verbose. There are alternatives that give you an better API to deal with http requests. The request is really popular.
To get data you need to make a GET request to a view you can find more information here. If you want to create a document you have to use PUT request to your database.
I am more into front end development and have recently started exploring Backbone.js into my app. I want to persist the model data to the server.
Could you please explain me the various way to save the Model data (using json format). I am using Java on server side. Also I have mainly seen REST being used to save data. As i am more into front end dev, i am not aware of REST and other similar stuff.
It would be great if someone could please explain me the process with some simple example.
Basically Models have a property called attributes which are the various values a certain model may have. Backbone uses JSON objects as a simple way to populate these values using various methods that take JSON objects. Example:
Donuts = Backbone.Model.extend({
defaults: {
flavor: 'Boston Cream', // Some string
price: '0.50' // Dollars
}
});
To populate the model there are a few ways to do so. For example, you can set up your model instance by passing in a JSON OR use method called set() which takes a JSON object of attributes.
myDonut = new Donut({'flavor':'lemon', 'price':'0.75'});
mySecondHelping = new Donut();
mySecondHelping.set({'flavor':'plain', 'price':'0.25'});
console.log(myDonut.toJSON());
// {'flavor':'lemon', 'price':'0.75'}
console.log(mySecondHelping.toJSON());
// {'flavor':'plain', 'price':'0.25'}
So this brings us up to saving models and persisting them either to a server. There is a whole slew of details regarding "What is REST/RESTful?" And it is kind of difficult to explain all this in a short blurb here. Specifically with regard to REST and Backbone saving, the thing to wrap your head around is the semantics of HTTP requests and what you are doing with your data.
You're probably used to two kinds of HTTP requests. GET and POST. In a RESTful environment, these verbs have special meaning for specific uses that Backbone assumes. When you want to get a certain resource from the server, (e.g. donut model I saved last time, a blog entry, an computer specification) and that resource exists, you do a GET request. Conversely, when you want to create a new resource you use POST.
Before I got into Backbone, I've never even touched the following two HTTP request methods. PUT and DELETE. These two verbs also have specific meaning to Backbone. When you want to update a resource, (e.g. Change the flavor of lemon donut to limon donut, etc.) you use a PUT request. When you want to delete that model from the server all together, you use a DELETE request.
These basics are very important because with your RESTful app, you probably will have a URI designation that will do the appropriate task based on the kind of request verb you use. For example:
// The URI pattern
http://localhost:8888/donut/:id
// My URI call
http://localhost:8888/donut/17
If I make a GET to that URI, it would get donut model with an ID of 17. The :id depends on how you are saving it server side. This could just be the ID of your donut resource in your database table.
If I make a PUT to that URI with new data, I'd be updating it, saving over it. And if I DELETE to that URI, then it would purge it from my system.
With POST, since you haven't created a resource yet it won't have an established resource ID. Maybe the URI target I want to create resources is simply this:
http://localhost:8888/donut
No ID fragment in the URI. All of these URI designs are up to you and how you think about your resources. But with regard to RESTful design, my understanding is that you want to keep the verbs of your actions to your HTTP request and the resources as nouns which make URIs easy to read and human friendly.
Are you still with me? :-)
So let's get back to thinking about Backbone. Backbone is wonderful because it does a lot of work for you. To save our donut and secondHelping, we simply do this:
myDonut.save();
mySecondHelping.save();
Backbone is smart. If you just created a donut resource, it won't have an ID from the server. It has something called a cID which is what Backbone uses internally but since it doesn't have an official ID it knows that it should create a new resource and it sends a POST request. If you got your model from the server, it will probably have an ID if all was right. In this case, when you save() Backbone assumes you want to update the server and it will send a PUT. To get a specific resource, you'd use the Backbone method .fetch() and it sends a GET request. When you call .destroy() on a model it will send the DELETE.
In the previous examples, I never explicitly told Backbone where the URI is. Let's do that in the next example.
thirdHelping = Backbone.Model.extend({
url: 'donut'
});
thirdHelping.set({id:15}); // Set the id attribute of model to 15
thirdHelping.fetch(); // Backbone assumes this model exists on server as ID 15
Backbone will GET the thirdHelping at http://localhost:8888/donut/15 It will simply add /donut stem to your site root.
If you're STILL with me, good. I think. Unless you're confused. But we'll trudge on anyway. The second part of this is the SERVER side. We've talked about different verbs of HTTP and the semantic meanings behind those verbs. Meanings that you, Backbone, AND your server must share.
Your server needs to understand the difference between a GET, POST, PUT, and DELETE request. As you saw in the examples above, GET, PUT, and DELETE could all point to the same URI http://localhost:8888/donut/07 Unless your server can differentiate between these HTTP requests, it will be very confused as to what to do with that resource.
This is when you start thinking about your RESTful server end code. Some people like Ruby, some people like .net, I like PHP. Particularly I like SLIM PHP micro-framework. SLIM PHP is a micro-framework that has a very elegant and simple tool set for dealing with RESTful activities. You can define routes (URIs) like in the examples above and depending on whether the call is GET, POST, PUT, or DELETE it will execute the right code. There are other solutions similar to SLIM like Recess, Tonic. I believe bigger frameworks like Cake and CodeIgniter also do similar things although I like minimal. Did I say I like Slim? ;-)
This is what excerpt code on the server might look (i.e. specifically regarding the routes.)
$app->get('/donut/:id', function($id) use ($app) {
// get donut model with id of $id from database.
$donut = ...
// Looks something like this maybe:
// $donut = array('id'=>7, 'flavor'=>'chocolate', 'price'=>'1.00')
$response = $app->response();
$response['Content-Type'] = 'application/json';
$response->body(json_encode($donut));
});
Here it's important to note that Backbone expects a JSON object. Always have your server designate the content-type as 'application/json' and encode it in json format if you can. Then when Backbone receives the JSON object it knows how to populate the model that requested it.
With SLIM PHP, the routes operate pretty similarly to the above.
$app->post('/donut', function() use ($app) {
// Code to create new donut
// Returns a full donut resource with ID
});
$app->put('/donut/:id', function($id) use ($app) {
// Code to update donut with id, $id
$response = $app->response();
$response->status(200); // OK!
// But you can send back other status like 400 which can trigger an error callback.
});
$app->delete('/donut/:id', function($id) use ($app) {
// Code to delete donut with id, $id
// Bye bye resource
});
So you've almost made the full round trip! Go get a soda. I like Diet Mountain Dew. Get one for me too.
Once your server processes a request, does something with the database and resource, prepares a response (whether it be a simple http status number or full JSON resource), then the data comes back to Backbone for final processing.
With your save(), fetch(), etc. methods - you can add optional callbacks on success and error. Here is an example of how I set up this particular cake:
Cake = Backbone.Model.extend({
defaults: {
type: 'plain',
nuts: false
},
url: 'cake'
});
myCake = new Cake();
myCake.toJSON() // Shows us that it is a plain cake without nuts
myCake.save({type:'coconut', nuts:true}, {
wait:true,
success:function(model, response) {
console.log('Successfully saved!');
},
error: function(model, error) {
console.log(model.toJSON());
console.log('error.responseText');
}
});
// ASSUME my server is set up to respond with a status(403)
// ASSUME my server responds with string payload saying 'we don't like nuts'
There are a couple different things about this example that. You'll see that for my cake, instead of set() ing the attributes before save, I simply passed in the new attributes to my save call. Backbone is pretty ninja at taking JSON data all over the place and handling it like a champ. So I want to save my cake with coconuts and nuts. (Is that 2 nuts?) Anyway, I passed in two objects to my save. The attributes JSON object AND some options. The first, {wait:true} means don't update my client side model until the server side trip is successful. The success call back will occur when the server successfully returns a response. However, since this example results in an error (a status other than 200 will indicate to Backbone to use the error callback) we get a representation of the model without the changes. It should still be plain and without nuts. We also have access to the error object that the server sent back. We sent back a string but it could be JSON error object with more properties. This is located in the error.responseText attribute. Yeah, 'we don't like nuts.'
Congratulations. You've made your first pretty full round trip from setting up a model, saving it server side, and back. I hope that this answer epic gives you an IDEA of how this all comes together. There are of course, lots of details that I'm cruising past but the basic ideas of Backbone save, RESTful verbs, Server-side actions, Response are here. Keep going through the Backbone documentation (which is super easy to read compared to other docs) but just keep in mind that this takes time to wrap your head around. The more you keep at it the more fluent you'll be. I learn something new with Backbone every day and it gets really fun as you start making leaps and see your fluency in this framework growing. :-)
EDIT: Resources that may be useful:
Other Similar Answers on SO:
How to generate model IDs with Backbone
On REST:
http://rest.elkstein.org/
http://www.infoq.com/articles/rest-introduction
http://www.recessframework.org/page/towards-restful-php-5-basic-tips