lib/core/Collection.js
var Base = require('./Base');
var Model = require('./Model');
var _ = require('lodash');
var _super = Base.prototype;
// Wrap an optional error callback with a fallback error event.
var wrapError = function (model, options) {
var error = options.error;
options.error = function(resp) {
if (error) error(model, resp, options);
model.trigger('error', model, resp, options);
};
};
// Create local references to array methods we'll want to use later.
var array = [];
var push = array.push;
var slice = array.slice;
var splice = array.splice;
// Default options for `Collection#set`.
var setOptions = {add: true, remove: true, merge: true};
var addOptions = {add: true, merge: false, remove: false};
var Collection = Base.extend({
'model': Model,
'initialize': function (models, options) {
var self = this;
options || (options = {});
this.options = options;
_super.initialize.call(self, options);
if (options.url) self.url = options.url;
if (options.model) self.model = options.model;
if (options.comparator !== void 0) self.comparator = options.comparator;
self._reset();
if (models) self.reset(models, _.extend({silent: true}, options));
},
// The JSON representation of a Collection is an array of the
// models' attributes.
toJSON: function(options) {
return this.map(function(model){ return model.toJSON(options); });
},
// Add a model, or list of models to the set.
add: function (models, collection, options) {
var self = this;
if (collection && !collection.models) {
options = collection;
}
var result = self.set(models, _.merge({}, options, addOptions));
// result.length && _.each(result.models, function (model) {
// model && _.each(model.attributes, function (value, key) {
// console.log('model', model.id, key)
// self.trigger('change:' + key, model, self);
// });
// });
return result;
},
// Remove a model, or a list of models from the set.
remove: function(models, options) {
models = _.isArray(models) ? models.slice() : [models];
options || (options = {});
var i, l, index, model;
for (i = 0, l = models.length; i < l; i++) {
model = this.get(models[i]);
if (!model) continue;
delete this._byId[model.id];
delete this._byId[model.cid];
index = this.indexOf(model);
this.models.splice(index, 1);
this.length--;
if (!options.silent) {
options.index = index;
model.trigger('remove', model, this, options);
}
this._removeReference(model);
}
return this;
},
// Update a collection by `set`-ing a new list of models, adding new ones,
// removing models that are no longer present, and merging models that
// already exist in the collection, as necessary. Similar to **Model#set**,
// the core operation for updating the data contained by the collection.
set: function(models, options) {
options = _.defaults(options || {}, setOptions);
// options = _.merge({}, this.options, options);
if (options.parse) models = this.parse(models, options);
if (!_.isArray(models)) models = models ? [models] : [];
var i, l, model, attrs, existing, sort;
var at = options.at;
var sortable = this.comparator && (at == null) && options.sort !== false;
var sortAttr = _.isString(this.comparator) ? this.comparator : null;
var toAdd = [], toRemove = [], modelMap = {};
// Turn bare objects into model references, and prevent invalid models
// from being added.
for (i = 0, l = models.length; i < l; i++) {
if (!(model = this._prepareModel(models[i], options))) continue;
// If a duplicate is found, prevent it from being added and
// optionally merge it into the existing model.
if (existing = this.get(model)) {
if (options.remove) modelMap[existing.cid] = true;
if (options.merge) {
existing.set(model.attributes, options);
if (sortable && !sort && existing.hasChanged(sortAttr)) sort = true;
}
// This is a new model, push it to the `toAdd` list.
} else if (options.add) {
toAdd.push(model);
// Listen to added models' events, and index models for lookup by
// `id` and by `cid`.
model.on('all', this._onModelEvent, this);
this._byId[model.cid] = model;
if (model.id != null) this._byId[model.id] = model;
}
}
// Remove nonexistent models if appropriate.
if (options.remove) {
for (i = 0, l = this.length; i < l; ++i) {
if (!modelMap[(model = this.models[i]).cid]) toRemove.push(model);
}
if (toRemove.length) this.remove(toRemove, options);
}
// See if sorting is needed, update `length` and splice in new models.
if (toAdd.length) {
if (sortable) sort = true;
this.length += toAdd.length;
if (at != null) {
splice.apply(this.models, [at, 0].concat(toAdd));
} else {
push.apply(this.models, toAdd);
}
}
// Silently sort the collection if appropriate.
if (sort) this.sort({silent: true});
if (options.silent) return this;
// Trigger `add` events.
for (i = 0, l = toAdd.length; i < l; i++) {
(model = toAdd[i]).trigger('add', model, this, options);
}
// Trigger `sort` if the collection was sorted.
if (sort) this.trigger('sort', this, options);
return this;
},
// When you have more items than you want to add or remove individually,
// you can reset the entire set with a new list of models, without firing
// any granular `add` or `remove` events. Fires `reset` when finished.
// Useful for bulk operations and optimizations.
reset: function(models, options) {
options || (options = {});
for (var i = 0, l = this.models.length; i < l; i++) {
this._removeReference(this.models[i]);
}
options.previousModels = this.models;
this._reset();
this.add(models, _.extend({silent: true}, options));
if (!options.silent) this.trigger('reset', this, options);
return this;
},
// Add a model to the end of the collection.
push: function(model, options) {
model = this._prepareModel(model, options);
this.add(model, _.extend({at: this.length}, options));
return model;
},
// Remove a model from the end of the collection.
pop: function(options) {
var model = this.at(this.length - 1);
this.remove(model, options);
return model;
},
// Add a model to the beginning of the collection.
unshift: function(model, options) {
model = this._prepareModel(model, options);
this.add(model, _.extend({at: 0}, options));
return model;
},
// Remove a model from the beginning of the collection.
shift: function(options) {
var model = this.at(0);
this.remove(model, options);
return model;
},
// Slice out a sub-array of models from the collection.
slice: function(begin, end) {
return this.models.slice(begin, end);
},
// Get a model from the set by id.
get: function(obj) {
if (obj == null) return void 0;
return this._byId[obj.id != null ? obj.id : obj.cid || obj];
},
// Get the model at the given index.
at: function(index) {
return this.models[index];
},
// Return models with matching attributes. Useful for simple cases of
// `filter`.
where: function(attrs, first) {
if (_.isEmpty(attrs)) return first ? void 0 : [];
return this[first ? 'find' : 'filter'](function(model) {
for (var key in attrs) {
if (attrs[key] !== model.get(key)) return false;
}
return true;
});
},
// Return the first model with matching attributes. Useful for simple cases
// of `find`.
findWhere: function(attrs) {
return this.where(attrs, true);
},
// Force the collection to re-sort itself. You don't need to call this under
// normal circumstances, as the set will maintain sort order as each item
// is added.
sort: function(options) {
if (!this.comparator) throw new Error('Cannot sort a set without a comparator');
options || (options = {});
// Run sort based on type of `comparator`.
if (_.isString(this.comparator) || this.comparator.length === 1) {
this.models = this.sortBy(this.comparator, this);
} else {
this.models.sort(_.bind(this.comparator, this));
}
if (!options.silent) this.trigger('sort', this, options);
return this;
},
// Figure out the smallest index at which a model should be inserted so as
// to maintain order.
sortedIndex: function(model, value, context) {
value || (value = this.comparator);
var iterator = _.isFunction(value) ? value : function(model) {
return model.get(value);
};
return _.sortedIndex(this.models, model, iterator, context);
},
// Pluck an attribute from each model in the collection.
pluck: function(attr) {
return _.invoke(this.models, 'get', attr);
},
// Fetch the default set of models for this collection, resetting the
// collection when they arrive. If `reset: true` is passed, the response
// data will be passed through the `reset` method instead of `set`.
fetch: function(options) {
options = options ? _.clone(options) : {};
if (options.parse === void 0) options.parse = true;
var success = options.success;
var collection = this;
options.success = function(resp) {
var method = options.reset ? 'reset' : 'set';
collection[method](resp, options);
if (success) success(collection, resp, options);
// collection.trigger('sync', collection, resp, options);
};
wrapError(this, options);
return this.sync('read', this, options);
},
'sync': function () {},
// Create a new instance of a model in this collection. Add the model to the
// collection immediately, unless `wait: true` is passed, in which case we
// wait for the server to agree.
create: function(model, options) {
options = options ? _.clone(options) : {};
if (!(model = this._prepareModel(model, options))) return false;
if (!options.wait) this.add(model, options);
var collection = this;
var success = options.success;
options.success = function(resp) {
if (options.wait) collection.add(model, options);
if (success) success(model, resp, options);
};
model.save(null, options);
return model;
},
// **parse** converts a response into a list of models to be added to the
// collection. The default implementation is just to pass it through.
parse: function(resp, options) {
return resp;
},
// Create a new collection with an identical list of models as this one.
clone: function() {
return new this.constructor(this.models);
},
// Private method to reset all internal state. Called when the collection
// is first initialized or reset.
_reset: function() {
this.length = 0;
this.models = [];
this._byId = {};
},
// Prepare a hash of attributes (or other model) to be added to this
// collection.
_prepareModel: function(attrs, options) {
if (attrs instanceof Model) {
if (!attrs.collection) attrs.collection = this;
return attrs;
}
options || (options = {});
options.collection = this;
var model = new this.model(attrs, _.merge({}, this.options, options));
if (!model._validate(attrs, options)) {
this.trigger('invalid', this, attrs, options);
return false;
}
return model;
},
// Internal method to sever a model's ties to a collection.
_removeReference: function(model) {
if (this === model.collection) delete model.collection;
model.off('all', this._onModelEvent, this);
},
// Internal method called every time a model in the set fires an event.
// Sets need to update their indexes when models change ids. All other
// events simply proxy through. "add" and "remove" events that originate
// in other collections are ignored.
_onModelEvent: function(event, model, collection, options) {
if ((event === 'add' || event === 'remove') && collection !== this) return;
if (event === 'destroy') this.remove(model, options);
if (model && event === 'change:' + model.idAttribute) {
delete this._byId[model.previous(model.idAttribute)];
if (model.id != null) this._byId[model.id] = model;
}
this.trigger.apply(this, arguments);
}
});
// Underscore methods that we want to implement on the Collection.
// 90% of the core usefulness of Backbone Collections is actually implemented
// right here:
var methods = ['forEach', 'each', 'map', 'collect', 'reduce', 'foldl',
'inject', 'reduceRight', 'foldr', 'find', 'detect', 'filter', 'select',
'reject', 'every', 'all', 'some', 'any', 'include', 'contains', 'invoke',
'max', 'min', 'toArray', 'size', 'first', 'head', 'take', 'initial', 'rest',
'tail', 'drop', 'last', 'without', 'indexOf', 'shuffle', 'lastIndexOf',
'isEmpty', 'chain'];
// Mix in each Underscore method as a proxy to `Collection#models`.
_.each(methods, function(method) {
Collection.prototype[method] = function() {
var args = slice.call(arguments);
args.unshift(this.models);
return _[method].apply(_, args);
};
});
// Underscore methods that take a property name as an argument.
var attributeMethods = ['groupBy', 'countBy', 'sortBy'];
// Use attributes instead of properties.
_.each(attributeMethods, function(method) {
Collection.prototype[method] = function(value, context) {
var iterator = _.isFunction(value) ? value : function(model) {
return model.get(value);
};
return _[method](this.models, iterator, context);
};
});
module.exports = Collection;