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DelayedCommandableMixin

Provides support for fetching permitted actions by an extra call after the primary node collection has been fetched. It depends on setting the commands URL query parameter as introduced by the api/v1/nodes/:id/nodes (V1) resource to specify just the default actions. The it issues an additional api/v2/actions/nodes call to enquire about the rest of the actions.

Server responses can contain permitted actions to be able to support enabling and disabling in the corresponding UI; how many and which ones should be checked by the server can be specified.

How to apply the mixin to a model​

var MyModel = Backbone.Model.extend({

  constructor: function MyModel(attributes, options) {
    Backbone.Model.prototype.constructor.apply(this, arguments);
    this
      .makeConnectable(options)
      .makeDelayedCommandable(options);
  },

  url: function () {
    var url = Url.combine(this.connector.connection.url, 'myresource'),
        query = Url.combineQueryString(
          this.getRequestedCommandsUrlQuery()
        );
    return query ? url + '?' + query : url;
  }

});

ConnectableMixin.mixin(MyModel.prototype);
DelayedCommandableMixin.mixin(MyModel.prototype);

This mixin us usually combined together with the ConnectableMixin or with another cumulated mixin which includes it.

How to use the mixin​

Set up the URL parameters by calling setDefaultActionCommands, resetDefaultActionCommands, setCommands and resetCommands and fetch the model:

// Set the commands for requesting when creating the model
var model = new MyModel(undefined, {
      connector: connector,
      commands: ['download', 'delete', 'reserve']
      defaultActionCommands: ['download'],
      delayRestCommands: true
    });
model.fetch();

// Set the commands for requesting after creating the model
model.setCommands(['download', 'delete', 'reserve']);
model.setDefaultActionCommands(['download']);
model.fetch();

makeDelayedCommandable(options) : this​

Must be called in the constructor to initialize the mixin functionality. Expects the Backbone.Model or Backbone.Collection constructor options passed in.

Recognized option properties:

commands : One or more command signatures to be requested for being checked. The value is handled the same way as the setCommands method does it. An empty array is the default.

defaultActionCommands : One or more command signatures to be requested for being checked immediately by the first call. The rest of commands specified by the commands parameter will be fetched later by the second call. The value is handled the same way as the setDefaultActionCommands method does it. An empty array is the default.

delayRestCommands : Enables delayed fetching of the non-default actions by a second server call. False is the default.

delayRestCommandsForModels : Enables delayed fetching of the non-default actions by a second server call for child models, which are created automatically by adding attribute objects to the collection; if the mixin is aplied to a collection, the parameter delayRestCommands does not apply to the child models; the delayRestCommandsForModels does. False is the default.

commands​

Command signatures to be requested for being checked (array of strings, empty by default, read-only).

defaultActionCommands​

Command signatures for being checked to be requested immediately by the first server call (array of strings, empty by default, read-only).

delayRestCommands​

: Says, if delayed fetching of the non-default actions by a second server call is enabled (boolean, false by default, read-only).

delayRestCommandsForModels​

: Says, if delayed fetching of the non-default actions by a second server call is enabled for child models, which are created automatically by adding attribute objects to the collection; if the mixin is aplied to a collection, the parameter delayRestCommands does not apply to the child models; the delayRestCommandsForModels does (boolean, false by default, read-only).

delayedActions​

A collection fetching the rest of non-default actions. If you need to wait until all permitted actions are received, you need to check the fetched status of this collection, or listen to the 'sync' even of this collection. The target collection, which you applied this mixin too will report that it is fetched immediately after the first server call is finished with the default actions only.

var model = new MyModel(undefined, {
      connector: connector,
      commands: ['download', 'delete', 'reserve']
      defaultActionCommands: ['download'],
      delayRestCommands: true
    });
model
    .once('sync', function () {
      // nodes with permitted default actions are available
    })
    .delayedActions.once('sync', function () {
      // nodes with all permitted actions are available
    })
    .fetch();

setCommands(names) : void​

Asks for one or more commands to be checked. The names parameter can be either string, or an array of strings. The string can contain a comma-delimited list, in which case it will be split to an array.

// Have two commands checked, option 1
model.setCommands(['delete', 'reserve']);
// Have two commands checked, option 2
model.setCommands('delete');
model.setCommands('reserve');
// Have two commands checked, option 3
model.setCommands('delete,reserve');

resetCommands(names) : void​

Prevents one or more commands from being checked. The names parameter can be either string, or an array of strings, or nothing. The string can contain a comma-delimited list, in which case it will be split to an array. If nothing is specified, all commands will be removed (not to be checked).

// Cancel all command checks and fetch the fresh data
model.resetCommands();
model.fetch();

setDefaultActionCommands(names) : void​

Asks for one or more commands to be checked immediately by the first server call. The names parameter can be either string, or an array of strings. The string can contain a comma-delimited list, in which case it will be split to an array. The rest of commands specified by the setCommands method will be fetched later by the second call.

// Have two commands checked, option 1
model.setCommands(['browse', 'download']);
// Have two commands checked, option 2
model.setCommands('browse');
model.setCommands('download');
// Have two commands checked, option 3
model.setCommands('browse,download');

resetDefaultActionCommands(names) : void​

Prevents one or more commands from being checked immediatley by the first server call. The names parameter can be either string, or an array of strings, or nothing. The string can contain a comma-delimited list, in which case it will be split to an array. If nothing is specified, all commands will be removed (not to be checked by the first server call).

// Have all commands fetched delayed by the second server call
model.setCommands(['browse', 'download']);
model.resetDefaultActionCommands();
model.fetch();

getRequestedCommandsUrlQuery() : string​

Formats the URL query parameters for the command investigation. They can be concatenated with other URL query parts (both object literals and strings) by Url.combineQueryString. If delayed action fetching is enabled, only the default actions will be returned by this method; the rest of specified actions fill be fetched by an additional server call later.

var url = ...,
    query = Url.combineQueryString(
      ...,
      this.getRequestedCommandsUrlQuery()
    );
if (query) {
  url = Url.appendQuery(url, query);
}

See Also​

ConnectableMixin, CommandableMixin