loopback-mixins-example
$ git clone https://github.com/strongloop/loopback-example-mixins
$ cd loopback-example-mixins
$ npm install
$ npm start
This example is a LoopBack project that uses the mixin functionality available in loopback-boot as of v2.8.0.
This example application shows mixins loading from several different locations like directories and modules as well as performing different actions like observing changes and adding model attributes. This README covers the mixin changes in both the model config and model definition.
Mixin Loading
Specify mixin locations relative to the server/model-config.json file. Multiple mixins can exist in a single directory. Once specified in the model-config.json file the mixin will be available in the LoopBack mixin registry but still needs to be configured for use in the model.
npm module
This loads the loopback-ds-timestamp-mixin module from the top level node_modules directory. Note that this module provides a mixin file time-stamp.js which is registered as the camel case TimeStamp name.
{
"_meta": {
...
"mixins": [
...
"../node_modules/loopback-ds-timestamp-mixin"
]
}
}
The common/mixins/ directory
{
"_meta": {
...
"mixins": [
...
"../common/mixins"
]
}
}
The local server/mixins/ directory
Because the model-config.json is within the server directory this loads the mixins from current mixins directory.
{
"_meta": {
...
"mixins": [
...
"./mixins"
]
}
}
Model config
In the model description file you must activate the mixin from the group you have loaded. In this application the common/models/dog.json file activates several mixins by adding them to the mixin object definition.
{
"name": "Dog",
"base": "PersistedModel",
...
"mixins": {
"TimeStamp": true,
"Tag": true,
"Squirrel": true
}
}
Mixins also have the ability to pass in options through this activation by using an object instead of true. These options are implemented by the mixin themselves, see the documentation provided by the mixin for more information on available options.
{
"name": "Dog",
"base": "PersistedModel",
...
"mixins": {
"TimeStamp": {
"required" : false
},
"Tag": true,
"Squirrel": true
}
}