AppJet JavaScript Library Reference: storage

Overview

Easy way to persist data between requests.

Importing the "storage" module gives you access to a root storage object. Any property you assign to this object in one request will be avialable in any subsequent requests.

The typical way to add a top-level property of storage is to check if it's defined and – if not – set it to some default value, as in the example below.

source: storage.js

examples

import("storage");

if (! storage.counter) {
    storage.counter = 0;
}

StorableObject(obj)

An object that can be stored directly, and is backed by our database. StorableObjects can be added to StorableCollections.

parameters

obj

properties

string id

examples

var s = new StorableObject();
s.message = "Hi there!";

storage.foo = s;

var s = new StorableObject({message: "Hi there!"});

var c = new StorableCollection();
c.add(s)

StorableCollection()

A StorableCollection persistently stores other StorableObjects.

methods

add(obj)

remove(obj)

filter(match)

sort(compare)

forEach(f)

size()

inherits

id() from StorableObject

examples

storage.foo = new StorableCollection();
storage.foo.add({name: "John"});
storage.foo.add({name: "Mary"});

storage.foo.forEach(printp);

getStorable(id)

Gets a StorableObject or StorableCollection by id.

parameters

string

id

The id of the object to be gotten.

returns

StorableObject The StorableObject whose id is id, or undefined if no such object exists.

examples

function get_editor() {
  // Objects passed between requests must be reachable from storage.
  var obj = storage.users.iterator().next();

  // In your edit page; "obj" is the object to edit.
  print(FORM({action: "/doedit", method: "post"},
             INPUT({type: "text", name: "title"}),
             INPUT({type: "hidden", name: "id", value: obj.id}),
             INPUT({type: "submit", name: "edit"})));
}

function post_doedit() {
  // In your form's action page.

  getStorable(request.param("id")).title = request.param("title");
}

StorableCollection.add(obj)

Adds a StorableObject to this collection.

parameters

object obj The object to add to this collection. If obj is not a StorableObject, a new StorableObject is created from obj by passing it to the StorableObject constructor, copying its properties.

examples

var c = new StorableCollection();
c.add({name: "John"});

StorableCollection.remove(obj)

Removes StorableObjects from this collection.

parameters

object obj The object to remove from this collection. If obj is a StorableObject, obj itself is removed from this collection. If obj is an collection or a view on a collection (such as one created by filter), then all objects provided in that collection are removed. Finally, if obj is just a plain object, then all members of this collection that have the same properties and values as obj are removed. Note: passing an {} removes all objects form this collection.

examples

var c = storage.users; // a StorableCollection
c.remove({name: "John"});

StorableCollection.filter(match)

Filters this collection based on a matching object.

parameters

object match The object to base a filter on. The returned view contains only those members of this StorableCollection whose properties have the same value as the ones in match. (Properties in the collection's members not present in match are ignored.) filter and sort are "chainable" operations; they can be applied to filtered and sorted views.

returns

A filtered view of this collection.

examples

var c = new StorableCollection();
c.add(new StorableObject({first_name: "Bob", last_name: "Smith"}));
c.add(new StorableObject({first_name: "John", last_name: "Smith"}));

var i = c.filter({first_name: "John"});
i.forEach(printp)      // prints John Smith's entry above.

// Filter and sort are chainable, as in this example:
var c = storage.users;  // a StorableCollection

var view = 
  c.filter({first_name: "John"}).sort(function(a, b) { return a.age - b.age })
view.forEach(printp)   // prints users named John, sorted from youngest to oldest.

StorableCollection.sort(compare)

Sorts this collection based on a sorting function.

parameters

function compare As with the function argument to Array.sort, compare should take two arguments a and b, and return a negative value, 0, or a positive value, if a < b, a = b, or a > b, respectively. filter and sort are "chainable" operations; they can be applied to filtered and sorted views.

returns

A sorted view of this collection.

examples

c.sort(function(a, b) { return a.date - b.date })

StorableCollection.forEach(f)

Executes a function once on each member of this collection. Note that forEach can only be called once on a view (though it can be called multiple times on a StorableCollection).

parameters

function f The function to call on each member of this collection. Returning false will cause forEach to abort.

StorableCollection.size()

Returns the number of elements in a collection. Can also be applied to filtered and sorted views of a collection. (This number may be approximate if your collection is very large.)

returns

number

The size of this collection.

examples

c.filter({status: 3}).size()

string

StorableObject.id

The id of a StorableObject is auto-generated. You can get the object associated with a given id using getStorable.