Prerequisite: Install command-line tools as described in Installation.
Recommended: Read LoopBack core concepts.
Create new application
To create a new application, run the LoopBack application generator:
If you’re using IBM API Connect tools, the command is:
$ apic loopback
If using StrongLoop tools:
The LoopBack application generator will greet you with some friendly ASCII art and prompt you for the name of the application.
loopback-getting-started. Then the generator will prompt you for the name of the directory to contain the project; press Enter to accept the default (the same as the application name):
_-----_ | | .--------------------------. |--(o)--| | Let's create a LoopBack | `---------´ | application! | ( _´U`_ ) '--------------------------' /___A___\ | ~ | __'.___.'__ ´ ` |° ´ Y ` [?] What's the name of your application? loopback-getting-started [?] Enter name of the directory to contain the project: loopback-getting-started
Note: You can use a different name for the application, but if you do, be sure to substitute your name for “loopback-getting-started” throughout the rest of this tutorial.
Then the tool will ask you what kind of application to create:
? What kind of application do you have in mind? (Use arrow keys) ❯ empty-server (An empty LoopBack API, without any configured models or datasources) hello-world (A project containing a controller, including a single vanilla Message and a single remote method) notes (A project containing a basic working example, including a memory database)
Press Enter to accept the default selection,
? What kind of application do you have in mind? (Use arrow keys) api-server (A LoopBack API server with local User auth) empty-server (An empty LoopBack API, without any configured models or datasources) ❯ hello-world (A project containing a controller, including a single vanilla Message and a single remote method) notes (A project containing a basic working example, including a memory database)
Arrow down and choose
The generator will then display messages as it scaffolds the application including:
- Initializing the project folder structure.
- Creating default JSON files.
- Downloading and installing dependent Node modules (as if you had manually done
Now that you’ve scaffolded the initial project, you’re going to create create a CoffeeShop model that will automatically have REST API endpoints.
Go into your new application directory, then run the LoopBack model generator:
$ cd loopback-getting-started
Then, using IBM API Connect developer toolkit:
$ apic create --type model
Using StrongLoop tools:
$ lb model
The generator will prompt for a model name. Enter CoffeeShop:
[?] Enter the model name: CoffeeShop
It will ask if you want to attach the model to any data sources that have already been defined.
At this point, only the default in-memory data source is available. Press Enter to select it:
... [?] Select the data-source to attach CoffeeShop to: (Use arrow keys) ❯ db (memory)
Then the generator will prompt you for the base class to use for the model. Since you will eventually connect this model to a persistent data source in a database, press down-arrow to choose PersistedModel, then press Enter:
[?] Select model's base class: (Use arrow keys) Model ❯ PersistedModel ACL AccessToken Application Change Checkpoint
One of the powerful advantages of LoopBack is that it automatically generates a REST API for your model. The generator will ask whether you want to expose this REST API.
Hit Enter again to accept the default and expose the CoffeeShop model via REST:
[?] Expose CoffeeShop via the REST API? (Y/n) Y
LoopBack automatically creates a REST route associated with your model using the plural of the model name. By default, it pluralizes the name for you (by adding “s”), but you can specify a custom plural form if you wish. See Exposing models over REST for all the details.
Press Enter to accept the default plural form (CoffeeShops):
[?] Custom plural form (used to build REST URL):
Next, you’ll be asked whether you want to create the model on the server only or in the
/common directory, where it can potentially be used by both server and client LoopBack APIs. Keep, the default, common, even though in this application you’ll only be working with server-side models:
? Common model or server only? ❯ common server
Every model has properties. Right now, you’re going to define one property, “name,” for the CoffeeShop model.
string as the property type (press Enter, since string is the default choice):
Let's add some CoffeeShop properties now. Enter an empty property name when done. [?] Property name: name invoke loopback:property [?] Property type: (Use arrow keys) ❯ string number boolean object array date buffer geopoint (other)
Each property can be optional or required. Enter
y to make
[?] Required? (y/N)
Then you’ll be prompted to enter a default value for the property; press Enter for no default value:
? Default value[leave blank for none]:
Then, you’ll be prompted to add another property. Follow the prompts to add a required property named “city.”
Let's add another CoffeeShop property. ? Property name: city ? Property type: string ? Required? Yes ? Default value[leave blank for none]:
End the model creation process by pressing Enter when prompted for the name of the next property.
The model generator will create two files in the application’s
common/models directory that define the model:
The LoopBack model generator,automatically converts camel-case model names (for example MyModel) to lowercase dashed names (my-model). For example, if you create a model named “FooBar” with the model generator, it creates files
common/models. However, the model name (“FooBar”) will be preserved via the model’s name property.
Check out the project structure
For all the details of the canonical LoopBack application structure, see Project layout reference.
Run the application
Start the application:
$ node . ... Browse your REST API at http://0.0.0.0:3000/explorer Web server listening at: http://0.0.0.0:3000/
Running your app with the
node command is appropriate when you’re developing on your local machine. In production, consider using API Connect or a process manager for scalability and reliability.
Open your browser to http://0.0.0.0:3000/ (on some systems, you may need to use http://localhost:3000 instead). You’ll see the default application response that displays some JSON with some status information; for example:
Through a set of simple steps using LoopBack, you’ve created a CoffeeShop model, specified its properties and then exposed it through REST.