realm-js/docs/collection.js

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////////////////////////////////////////////////////////////////////////////
//
// Copyright 2016 Realm Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////
/**
* Abstract base class containing methods shared by {@link Realm.List} and {@link Realm.Results}.
*
* A Realm Collection is a homogenous sequence of values of any of the types
* that can be stored as properties of Realm objects. A collection can be
* accessed in any of the ways that a normal Javascript Array can, including
* subscripting, enumerating with `for-of` and so on.
*
* A Collection always reflect the current state of the Realm. The one exception to this is
* when using `for...in` or `for...of` enumeration, which will always enumerate over the
* objects which matched the query when the enumeration is begun, even if some of them are
* deleted or modified to be excluded by the filter during the enumeration.
*
* @memberof Realm
* @since 0.11.0
*/
class Collection {
/**
* The number of values in the collection.
* @type {number}
* @readonly
*/
get length() {}
/**
* The {@linkplain Realm~PropertyType type} of values in the collection.
* @type {string}
* @readonly
* @since 2.0.0
*/
get type() {}
/**
* Whether `null` is a valid value for the collection.
* @type {boolean}
* @readonly
* @since 2.0.0
*/
get optional() {}
/**
* Checks if this collection has not been deleted and is part of a valid Realm.
* @returns {boolean} indicating if the collection can be safely accessed.
* @since 0.14.0
*/
isValid() {}
/**
* Returns new _Results_ that represent this collection being filtered by the provided query.
*
* @param {string} query - Query used to filter objects from the collection.
* @param {...any} [arg] - Each subsequent argument is used by the placeholders
* (e.g. `$0`, `$1`, `$2`, …) in the query.
* @throws {Error} If the query or any other argument passed into this method is invalid.
* @returns {Realm.Results<T>} filtered according to the provided query.
*
* This is currently only supported for collections of Realm Objects.
*
* See {@tutorial query-language} for details about the query language.
* @example
* let merlots = wines.filtered('variety == "Merlot" && vintage <= $0', maxYear);
*/
filtered(query, ...arg) {}
/**
* Returns new _Results_ that represent a sorted view of this collection.
*
* A collection of Realm Objects can be sorted on one or more properties of
* those objects, or of properties of objects linked to by those objects.
* To sort by a single property, simply pass the name of that property to
* `sorted()`, optionally followed by a boolean indicating if the sort should be reversed.
* For more than one property, you must pass an array of
* {@linkplain Realm.Collection~SortDescriptor sort descriptors} which list
* which properties to sort on.
*
* Collections of other types sort on the values themselves rather than
* properties of the values, and so no property name or sort descriptors
* should be supplied.
*
* @example
* // Sort wines by age
* wines.sorted('age')
* @example
* // Sort wines by price in descending order, then sort ties by age in
* // ascending order
* wines.sorted([['price', false], ['age'])
* @example
* // Sort a list of numbers in ascending order
* let sortedPrices = wine.pricesSeen.sort()
* @example
* // Sort people by how expensive their favorite wine is
* people.sort("favoriteWine.price")
*
* @param {string|Realm.Collection~SortDescriptor[]} [descriptor] - The property name(s) to sort the collection on.
* @param {boolean} [reverse=false] - Sort in descending order rather than ascended.
* May not be supplied if `descriptor` is an array of sort descriptors.
* @throws {Error} If a specified property does not exist.
* @returns {Realm.Results<T>} sorted according to the arguments passed in.
*/
sorted(descriptor, reverse) {}
/**
* Create a frozen snapshot of the collection.
*
* Values added to and removed from the original collection will not be
* reflected in the _Results_ returned by this method, including if the
* values of properties are changed to make them match or not match any
* filters applied.
*
* This is **not** a _deep_ snapshot. Realm objects contained in this
* snapshot will continue to update as changes are made to them, and if
* they are deleted from the Realm they will be replaced by `null` at the
* respective indices.
*
* @returns {Realm.Results<T>} which will **not** live update.
*/
snapshot() {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/entries Array.prototype.entries}
* @returns {Realm.Collection~Iterator<T>} of each `[index, object]` pair in the collection
* @since 0.11.0
*/
entries() {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/keys Array.prototype.keys}
* @returns {Realm.Collection~Iterator<T>} of each index in the collection
* @since 0.11.0
*/
keys() {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/values Array.prototype.values}
* @returns {Realm.Collection~Iterator<T>} of each Realm object in the collection
* @since 0.11.0
*/
values() {}
/**
* This is the same method as the {@link Realm.Collection#values values()} method.
* Its presence makes collections _iterable_, thus able to be used with ES6
* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of `for-of`}
* loops,
* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator `...`}
* spread operators, and more.
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/iterator Symbol.iterator}
* and the {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#iterable iterable protocol}
* @returns {Realm.Collection~Iterator<T>} of each Realm object in the collection
* @since 0.11.0
* @example
* for (let object of collection) {
* // do something with each object
* }
*/
[Symbol.iterator]() {}
/**
* Joins all objects in the collection into a string.
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join Array.prototype.join}
* @param {string} [separator=","] - A string to separate the return values of the
* `toString()` method being called on each object in the collection.
* @returns {string}
* @since 0.11.0
*/
join(separator) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice Array.prototype.slice}
* @param {number} [start=0] - The start index. If negative, then the start index will be
* counted from the end of the collection.
* @param {number} [end] - The end index. The objects up to, but not including, the end
* index will be include in the return value. If negative, then the end index will be
* counted from the end of the collection. If omitted, then all objects from the start
* index will be included in the return value.
* @returns {T[]} containing the objects from the start index up to, but not
* including, the end index.
* @since 0.11.0
*/
slice(start, end) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find Array.prototype.find}
* @param {function} callback - Function to execute on each object in the collection.
* If this function returns `true`, then that object will be returned by this method.
* This function takes three arguments:
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [thisArg] - The value of `this` when `callback` is called.
* @returns {T|undefined} if the `callback` did not return `true` for any object
* in the collection.
* @since 0.11.0
*/
find(callback, thisArg) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex Array.prototype.findIndex}
* @param {function} callback - Function to execute on each object in the collection.
* If this function returns `true`, then the index of that object will be returned
* by this method. This function takes three arguments:
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [thisArg] - The value of `this` when `callback` is called.
* @returns {number} representing the index where the `callback` returned `true`, or `-1`
* if `true` was never returned.
* @since 0.11.0
*/
findIndex(callback, thisArg) {}
/**
Finds the index of the given object in the collection.
* @param {T} object - The value to search for in the collection.
* @throws {Error} If the argument is a {@link Realm.Object} that does not
* belong to the same Realm as the collection.
* @returns {number} representing the index where the value was found, or
* `-1` if not in collection.
* @since 1.8.2
*/
indexOf(object) {}
/**
* Returns the minimum value of the values in the collection or of the
* given property among all the objects in the collection, or `undefined`
* if the collection is empty.
*
* Only supported for int, float, double and date properties. `null` values
* are ignored entirely by this method and will not be returned.
*
* @param {string} [property] - For a collection of objects, the property to take the minimum of.
* @throws {Error} If no property with the name exists or if property is not numeric/date.
* @returns {number} the minimum value.
* @since 1.12.1
*/
min(property) {}
/**
* Returns the maximum value of the values in the collection or of the
* given property among all the objects in the collection, or `undefined`
* if the collection is empty.
*
* Only supported for int, float, double and date properties. `null` values
* are ignored entirely by this method and will not be returned.
*
* @param {string} [property] - For a collection of objects, the property to take the maximum of.
* @throws {Error} If no property with the name exists or if property is not numeric/date.
* @returns {number} the maximum value.
* @since 1.12.1
*/
max(property) {}
/**
* Computes the sum of the values in the collection or of the given
* property among all the objects in the collection, or 0 if the collection
* is empty.
*
* Only supported for int, float and double properties. `null` values are
* ignored entirely by this method.
* @param {string} [property] - For a collection of objects, the property to take the sum of.
* @throws {Error} If no property with the name exists or if property is not numeric.
* @returns {number} the sum.
* @since 1.12.1
*/
sum(property) {}
/**
* Computes the average of the values in the collection or of the given
* property among all the objects in the collection, or `undefined` if the collection
* is empty.
*
* Only supported for int, float and double properties. `null` values are
* ignored entirely by this method and will not be factored into the average.
* @param {string} [property] - For a collection of objects, the property to take the average of.
* @throws {Error} If no property with the name exists or if property is not numeric.
* @returns {number} the sum.
* @since 1.12.1
*/
avg(property) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach Array.prototype.forEach}
* @param {function} callback - Function to execute on each object in the collection.
* This function takes three arguments:
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [thisArg] - The value of `this` when `callback` is called.
* @since 0.11.0
*/
forEach(callback, thisArg) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every Array.prototype.every}
* @param {function} callback - Function to execute on each object in the collection.
* If this function returns `true` for every object, then this method will return `true`.
* This function takes three arguments:
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [thisArg] - The value of `this` when `callback` is called.
* @returns {boolean} representing if `callback` returned `true` for every object in the
* collection.
* @since 0.11.0
*/
every(callback, thisArg) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some Array.prototype.some}
* @param {function} callback - Function to execute on each object in the collection.
* If this function ever returns `true`, then this method will return `true`.
* This function takes three arguments:
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [thisArg] - The value of `this` when `callback` is called.
* @returns {boolean} `true` when `callback` returns `true` for an object in the collection,
* otherwise `false`.
* @since 0.11.0
*/
some(callback, thisArg) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map Array.prototype.map}
* @param {function} callback - Function to execute on each object in the collection.
* This function takes three arguments:
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [thisArg] - The value of `this` when `callback` is called.
* @returns {any[]} the return values of `callback` after being called on every object
* in the collection.
* @since 0.11.0
*/
map(callback, thisArg) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce Array.prototype.reduce}
* @param {function} callback - Function to execute on each object in the collection.
* This function takes four arguments:
* - `previousValue` The value previously returned in the last invocation of the callback,
* or `initialValue`, if supplied.
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [initialValue] - The value to use as the first argument to the first call
* of the `callback`.
* @throws {TypeError} If the collection is empty and no `initialValue` was supplied.
* @returns {any} the value returned by the final invocation of `callback`, _except_ for
* the following special cases:
* - If collection consists of a single object, and no `initalValue` was supplied, then
* that object will be returned.
* - If the collection is empty, then `initialValue` _must_ be supplied and will be returned.
* @since 0.11.0
*/
reduce(callback, initialValue) {}
/**
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduceRight Array.prototype.reduceRight}
* @param {function} callback - Function to execute on each object, from **right to left**,
* in the collection. This function takes four arguments:
* - `previousValue` The value previously returned in the last invocation of the callback,
* or `initialValue`, if supplied.
* - `object` The current object being processed in the collection.
* - `index` The index of the object being processed in the collection.
* - `collection` The collection itself.
* @param {object} [initialValue] - The value to use as the first argument to the first call
* of the `callback`.
* @throws {TypeError} If the collection is empty and no `initialValue` was supplied.
* @returns {any} the value returned by the final invocation of `callback`, _except_ for
* the following special cases:
* - If collection consists of a single object, and no `initalValue` was supplied, then
* that object will be returned.
* - If the collection is empty, then `initialValue` _must_ be supplied and will be returned.
* @since 0.11.0
*/
reduceRight(callback, initialValue) {}
/**
* Add a listener `callback` which will be called when a **live** collection instance changes.
* @param {function(collection, changes)} callback - A function to be called when changes occur.
* The callback function is called with two arguments:
* - `collection`: the collection instance that changed,
* - `changes`: a dictionary with keys `insertions`, `modifications` and `deletions`,
* each containing a list of indices that were inserted, updated or deleted respectively.
* @throws {Error} If `callback` is not a function.
* @example
* wines.addListener((collection, changes) => {
* // collection === wines
* console.log(`${changes.insertions.length} insertions`);
* console.log(`${changes.modifications.length} modifications`);
* console.log(`${changes.deletions.length} deletions`);
* console.log(`new size of collection: ${collection.length}`);
* });
*/
addListener(callback) {}
/**
* Remove the listener `callback` from the collection instance.
* @param {function(collection, changes)} callback - Callback function that was previously
* added as a listener through the {@link Collection#addListener addListener} method.
* @throws {Error} If `callback` is not a function.
*/
removeListener(callback) {}
/**
* Remove all `callback` listeners from the collection instance.
*/
removeAllListeners(name) {}
}
/**
* This is an ES6 iterator.
* @typedef Realm.Collection~Iterator
* @property {function} next - Returns an object with two properties:
* - `done` `true` if the iterator is done iterating through items in the collection,
* otherwise `false`
* - `value` the next item being iterated through in the collection, or `undefined` when
* `done` is `true`
* @property {function} Symbol.iterator - This method simply returns `this`, thus making this
* iterator itself _iterable_ (i.e. usable in
* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of `for-of`}
* loops, with the
* {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator `...`}
* spread operator, and more).
* @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#iterator iterator protocol}
*/
/**
* A sort descriptor is either a string containing one or more property names
* separate by dots, **or** an array with two items: `[propertyName, reverse]`.
*
* @typedef Realm.Collection~SortDescriptor
* @type {string|Array}
*/