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import EventMixin from './EventMixin.js'
/*
The parent class for DataModel and DataCollection
It holds the event mixin and the generic function of fetching data from a remote service
*/
let DataObject = EventMixin(
class {
constructor(options={}){
this.options = options
this._new = true // True until the first fetch returns, regardless of http status
this.cleanedUp = false
}
cleanup(){
if(this.cleanedUp) return
this.cleanedUp = true
this.clearListeners()
}
// Return true until a fetch (even a failed fetch) returns
get isNew(){
return this._new
}
// Return the URL (relative or full) as a string for the endpoint used by this.fetch
get url(){
throw new Error('Extending classes must implement url()')
}
// Clear out old data and set it to data, should trigger a 'reset' event
reset(data={}){
throw new Error('Extending classes must implement reset')
}
parse(data){
// Extending classes can override this to parse the data received via a fetch
return data
}
equals(obj){
// Extending classes can override this to allow less strict equality
return this === obj
}
onFirstReset(func){
// If already reset, immediately call func, otherwise wait until the first reset and then call func
if(this._new){
this.addListener(() => {
func(this)
}, 'reset', true)
} else {
func(this)
}
}
get fetchOptions(){
// Extending classes can override this to add headers, methods, etc to the fetch call
return {
credentials: 'same-origin'
}
}
fetch(){
// Ask the server for data for this model or collection
return new Promise(function(resolve, reject){
this.trigger('fetching', this)
fetch(this.url, this.fetchOptions).then(response => {
if(response.status != 200){
throw 'Fetch failed with status ' + response.status
}
return response.json()
}).then(data => {
data = this.parse(data)
this._new = false
this.reset(data)
this.trigger('fetched', this, data, null)
resolve(this)
}).catch(err => {
this._new = false
this.trigger('fetched', this, null, err)
reject(err)
})
}.bind(this))
}
save(){
// Tell the server to create (POST) or update (PUT) this model or collection
return new Promise(function(resolve, reject){
this.trigger('saving', this)
let options = Object.assign({}, this.fetchOptions)
if(this.isNew){
options.method = 'post'
} else {
options.method = 'put'
}
options.body = JSON.stringify(this.data)
fetch(this.url, options).then(response => {
if(response.status != 200){
throw 'Save failed with status ' + response.status
}
return response.json()
}).then(data => {
data = this.parse(data)
this.reset(data)
this._new = false
this.trigger('saved', this, data, null)
resolve(this)
}).catch(err => {
this.trigger('saved', this, null, err)
reject(err)
})
}.bind(this))
}
delete(){
return new Promise(function(resolve, reject){
this.trigger('deleting', this)
let options = Object.assign({}, this.fetchOptions)
options.method = 'delete'
fetch(this.url, options).then(response => {
if(response.status != 200){
throw 'Delete failed with status ' + response.status
}
this.trigger('deleted', this, null)
resolve()
}).catch(err => {
this.trigger('deleted', this, err)
reject(err)
})
}.bind(this))
}
}
)
DataObject._NO_CHANGE = Symbol('no change')
export default DataObject