Falcor

A JavaScript library for efficient data fetching

Data fetching
Netflix/falcornetflix.github.io/falcorfalcor

README


Falcor

Build Status Coverage Status

2.0


2.0 is the current stable Falcor release. 0.x and 1.x users are
welcome to upgrade.

-   [Breaking changes between 1.x and 2.0](https://github.com/Netflix/falcor/blob/master/MIGRATIONS.md).
-   [Breaking changes between 0.x and 1.x](https://github.com/Netflix/falcor/blob/1.0.0/MIGRATIONS.md).

Roadmap


Issues we're tracking as part of our roadmap are tagged with the
roadmap
label. They are split into
enhancement,
stability,
performance,
tooling,
infrastructure
and
documentation
categories, with near, medium and longer term labels to convey a broader sense
of the order in which we plan to approach them.

Getting Started


You can check out a working example server for Netflix-like application right now. Alternately, you
can go through this barebones tutorial in which we use the Falcor Router to
create a Virtual JSON resource. In this tutorial we will use Falcor's express
middleware to serve the Virtual JSON resource on an application server at the
URL /model.json. We will also host a static web page on the same server which
retrieves data from the Virtual JSON resource.

Creating a Virtual JSON Resource


In this example we will use the falcor Router to build a Virtual JSON resource
on an app server and host it at /model.json. The JSON resource will contain
the following contents:

  1. ``` js
  2. {
  3.   "greeting": "Hello World"
  4. }
  5. ```

Normally, Routers retrieve the data for their Virtual JSON resource from backend
datastores or other web services on-demand. However, in this simple tutorial, the
Router will simply return static data for a single key.

First we create a folder for our application server.

  1. ``` sh
  2. $ mkdir falcor-app-server
  3. $ cd falcor-app-server
  4. $ npm init
  5. ```

Now we install the falcor Router.

  1. ``` sh
  2. $ npm install falcor-router --save
  3. ```

Then install express and falcor-express. Support for restify is also available,
as is support for hapi via a [third-party
implementation](https://github.com/Netflix/falcor-hapi).

  1. ``` sh
  2. $ npm install express --save
  3. $ npm install falcor-express --save
  4. ```

Now we create an index.js file with the following contents:

  1. ``` js
  2. // index.js
  3. const falcorExpress = require("falcor-express");
  4. const Router = require("falcor-router");

  6. const express = require("express");
  7. const app = express();

  9. app.use(
  10.     "/model.json",
  11.     falcorExpress.dataSourceRoute(function (req, res) {
  12.         // create a Virtual JSON resource with single key ('greeting')
  13.         return new Router([
  14.             {
  15.                 // match a request for the key 'greeting'
  16.                 route: "greeting",
  17.                 // respond with a PathValue with the value of 'Hello World.'
  18.                 get: () => ({ path: ["greeting"], value: "Hello World" }),
  19.             },
  20.         ]);
  21.     })
  22. );

  24. // serve static files from current directory
  25. app.use(express.static(__dirname + "/"));

  27. app.listen(3000);
  28. ```

Now we run the server, which will listen on port 3000 for requests for
/model.json.

  1. ``` sh
  2. $ node index.js
  3. ```

Retrieving Data from the Virtual JSON resource


Now that we've built a simple virtual JSON document with a single read-only key
greeting, we will create a test web page and retrieve this key from the
server.

Create an index.html file with the following contents:

  1. ``` html
  3. <html>
  4.     <head>
  5.         
  6.         <script src="https://netflix.github.io/falcor/build/falcor.browser.js"></script>
  7.         
  8.         
  9.         <script>
  10.             var model = falcor({
  11.                 source: new falcor.HttpDataSource("/model.json"),
  12.             });
  14.             // retrieve the "greeting" key from the root of the Virtual JSON resource
  15.             model.get("greeting").then(function (response) {
  16.                 document.write(response.json.greeting);
  17.             });
  18.         </script>
  19.     </head>
  20.     <body></body>
  21. </html>
  22. ```

Now visit http://localhost:3000/index.html and you should see the message
retrieved from the server:

  1. ```
  2. Hello World
  3. ```

Steps to publish new version


-   Make pull request with feature/bug fix and tests
-   Merge pull request into master after code review and passing Travis CI checks
-   Run git checkout master to open master branch locally
-   Run git pull to merge latest code, including built dist/ and docs/ by Travis
-   Run npm run dist to build dist/ locally
    -   Ensure the built files are not different from those built by Travis CI, hence creating no change to commit
-   Update CHANGELOG with features/bug fixes to be released in the new version and commit
-   Run npm version patch (or minor, major, etc) to create a new git commit and tag
-   Run git push origin master && git push --tags to push code and tags to github
-   Run npm publish to publish the latest version to NPM

Additional Resources


-   For detailed high-level documentation explaining the Model, the Router, and JSON
    Graph check out the Falcor website.

-   API documentation

-   For a working example of a Router, check out the
    falcor-router-demo.

-   For questions and discussion, use [Stack
    Overflow](https://stackoverflow.com/questions/tagged/falcor).