- Author:
- David Nickerson <nickerso@users.sourceforge.net>
- Date:
- 2009-07-16 02:00:03+12:00
- Desc:
- the starting point for the HH tutorial example
- Permanent Source URI:
- https://models.fieldml.org/workspace/a1/rawfile/f6a8f90307388eb4b040ee3566b84d88b59247f7/dojo-presentation/js/dojo/dojox/json/ref.js
dojo.provide("dojox.json.ref");
dojo.require("dojo.date.stamp");
// summary:
// Adds advanced JSON {de}serialization capabilities to the base json library.
// This enhances the capabilities of dojo.toJson and dojo.fromJson,
// adding referencing support, date handling, and other extra format handling.
// On parsing, references are resolved. When references are made to
// ids/objects that have been loaded yet, the loader function will be set to
// _loadObject to denote a lazy loading (not loaded yet) object.
dojox.json.ref.resolveJson = function(/*Object*/ root,/*Object?*/ args){
// summary:
// Indexes and resolves references in the JSON object.
// description:
// A JSON Schema object that can be used to advise the handling of the JSON (defining ids, date properties, urls, etc)
//
// root:
// The root object of the object graph to be processed
// args:
// Object with additional arguments:
//
// The *index* parameter.
// This is the index object (map) to use to store an index of all the objects.
// If you are using inter-message referencing, you must provide the same object for each call.
// The *defaultId* parameter.
// This is the default id to use for the root object (if it doesn't define it's own id)
// The *idPrefix* parameter.
// This the prefix to use for the ids as they enter the index. This allows multiple tables
// to use ids (that might otherwise collide) that enter the same global index.
// idPrefix should be in the form "/Service/". For example,
// if the idPrefix is "/Table/", and object is encountered {id:"4",...}, this would go in the
// index as "/Table/4".
// The *idAttribute* parameter.
// This indicates what property is the identity property. This defaults to "id"
// The *schemas* parameter
// This provides a map of schemas, from which prototypes can be retrieved
// The *loader* parameter
// This is a function that is called added to the reference objects that can't be resolved (lazy objects)
// return:
// An object, the result of the processing
args = args || {};
var idAttribute = args.idAttribute || 'id';
var prefix = args.idPrefix || '/';
var index = args.index || {}; // create an index if one doesn't exist
var ref,reWalk=[];
var pathResolveRegex = /^(.*\/)?(\w+:\/\/)|[^\/\.]+\/\.\.\/|^.*\/(\/)/;
function walk(it,stop,defaultId){
// this walks the new graph, resolving references and making other changes
var update, val, id = it[idAttribute] || defaultId;
if(id !== undefined){
id = (prefix + id).replace(pathResolveRegex,'$2$3');
}
var target = it;
if(id !== undefined){ // if there is an id available...
it.__id = id;
// if the id already exists in the system, we should use the existing object, and just
// update it... as long as the object is compatible
if(index[id] && ((it instanceof Array) == (index[id] instanceof Array))){
target = index[id];
delete target.$ref; // remove this artifact
update = true;
}else{
var proto = args.schemas && (!(it instanceof Array)) && // won't try on arrays to do prototypes, plus it messes with queries
(val = id.match(/^(.+\/)[^\.\[]*$/)) && // if it has a direct table id (no paths)
(val = args.schemas[val[1]]) && val.prototype; // and if has a prototype
if(proto){
// if the schema defines a prototype, that needs to be the prototype of the object
var F = function(){};
F.prototype = proto;
target = new F();
}
}
index[id] = target; // add the prefix, set _id, and index it
}
for(var i in it){
if((typeof (val=it[i]) =='object') && val){
ref=val.$ref;
if(ref){ // a reference was found
var stripped = ref.replace(/\\./g, '@').replace(/"[^"\\\n\r]*"/g, '');// trim it
if(/[\w\[\]\.\$ \/\r\n\t]/.test(stripped) && !/\=|((^|\W)new\W)/.test(stripped)){
// make sure it is a safe reference
delete it[i];// remove the property so it doesn't resolve to itself in the case of id.propertyName lazy values
var path = ref.match(/(^\.*[^\.\[]+)([\.\[].*)?/); // divide along the path
if((ref = (path[1]=='$' || path[1]=='this') ? root : index[(prefix + path[1]).replace(pathResolveRegex,'$2$3')]) && // a $ indicates to start with the root, otherwise start with an id
// // starting point was found, use eval to resolve remaining property references
// // need to also make reserved words safe by replacing with index operator
(ref = path[2] ? eval('ref' + path[2].replace(/\.([^\.]+)/g,'["$1"]')) : ref)){
// otherwise, no starting point was found (id not found), if stop is set, it does not exist, we have
// unloaded reference, if stop is not set, it may be in a part of the graph not walked yet,
// we will wait for the second loop
val = ref;
}else{
if(!stop){
var rewalking;
if(!rewalking){
reWalk.push(target); // we need to rewalk it to resolve references
}
rewalking = true; // we only want to add it once
}else{
val = walk(val, false, val.$ref);
// create a lazy loaded object
val._loadObject = args.loader;
}
}
}
}else{
if(!stop){ // if we are in stop, that means we are in the second loop, and we only need to check this current one,
// further walking may lead down circular loops
val = walk(val,reWalk==it,id && (id + ('[' + dojo._escapeString(i) + ']')));
}
}
}
it[i] = val;
if(target!=it){// performance guard
var old = target[i];
target[i] = val; // update the target
if(update && val !== old){ // only update if it changed
if(index.onUpdate){
index.onUpdate(target,i,old,val); // call the listener for each update
}
}
}
}
if(update){
// this means we are updating, we need to remove deleted
for(i in target){
if(!it.hasOwnProperty(i) && i != '__id' && !(target instanceof Array && isNaN(i))){
if(index.onUpdate){
index.onUpdate(target,i,target[i],undefined); // call the listener for each update
}
delete target[i];
while(target instanceof Array && target.length && target[target.length-1] === undefined){
// shorten the target if necessary
target.length--;
}
}
}
}else{
if(index.onLoad){
index.onLoad(target);
}
}
return target;
}
if(root && typeof root == 'object'){
root = walk(root,false,args.defaultId); // do the main walk through
walk(reWalk,false); // re walk any parts that were not able to resolve references on the first round
}
return root;
};
dojox.json.ref.fromJson = function(/*String*/ str,/*Object?*/ args){
// summary:
// evaluates the passed string-form of a JSON object.
//
// str:
// a string literal of a JSON item, for instance:
// '{ "foo": [ "bar", 1, { "baz": "thud" } ] }'
// args: See resolveJson
//
// return:
// An object, the result of the evaluation
function ref(target){ // support call styles references as well
return {$ref:target};
}
var root = eval('(' + str + ')'); // do the eval
if(root){
return this.resolveJson(root, args);
}
return root;
};
dojox.json.ref.toJson = function(/*Object*/ it, /*Boolean?*/ prettyPrint, /*Object?*/ idPrefix){
// summary:
// Create a JSON serialization of an object.
// This has support for referencing, including circular references, duplicate references, and out-of-message references
// id and path-based referencing is supported as well and is based on http://www.json.com/2007/10/19/json-referencing-proposal-and-library/.
//
// it:
// an object to be serialized.
//
// prettyPrint:
// if true, we indent objects and arrays to make the output prettier.
// The variable dojo.toJsonIndentStr is used as the indent string
// -- to use something other than the default (tab),
// change that variable before calling dojo.toJson().
//
// idPrefix: The prefix that has been used for the absolute ids
//
// return:
// a String representing the serialized version of the passed object.
var useRefs = dojox.json.ref.useRefs;
// dojox.json.ref.useRefs:
// Indicates if the serializer should be encouraged to use references to existing objects.
// If this is not true, the serializer will only use references when necessary (for circular references).
idPrefix = idPrefix || ''; // the id prefix for this context
var paths={};
function serialize(it,path,_indentStr){
if(typeof it == 'object' && it){
var value;
if(it instanceof Date){ // properly serialize dates
return '"' + dojo.date.stamp.toISOString(it,{zulu:true}) + '"';
}
var id = it.__id;
if(id){ // we found an identifiable object, we will just serialize a reference to it... unless it is the root
if(path != '$' && (useRefs || paths[id])){
var ref = id; // a pure path based reference, leave it alone
if(id.charAt(0)!='$'){
if(id.substring(0, idPrefix.length) == idPrefix){ // see if the reference is in the current context
// a reference with a prefix matching the current context, the prefix should be removed
ref = id.substring(idPrefix.length);
}else{
// a reference to a different context, assume relative url based referencing
ref = id;
}
}
return serialize({
$ref: ref
});
}
path = id;
}else{
it.__id = path; // we will create path ids for other objects in case they are circular
paths[path] = it;// save it here so they can be deleted at the end
}
_indentStr = _indentStr || "";
var nextIndent = prettyPrint ? _indentStr + dojo.toJsonIndentStr : "";
var newLine = prettyPrint ? "\n" : "";
var sep = prettyPrint ? " " : "";
if(it instanceof Array){
var res = dojo.map(it, function(obj,i){
var val = serialize(obj, path + '[' + i + ']', nextIndent);
if(typeof val != "string"){
val = "undefined";
}
return newLine + nextIndent + val;
});
return "[" + res.join("," + sep) + newLine + _indentStr + "]";
}
var output = [];
for(var i in it){
if(it.hasOwnProperty(i)){
var keyStr;
if(typeof i == "number"){
keyStr = '"' + i + '"';
}else if(typeof i == "string" && i.charAt(0) != '_'){
keyStr = dojo._escapeString(i);
}else{
// skip non-string or number keys
continue;
}
var val = serialize(it[i],path+(i.match(/^[a-zA-Z]\w*$/) ? // can we use simple .property syntax?
('.' + i) : // yes, otherwise we have to escape it
('[' + dojo._escapeString(i) + ']')),nextIndent);
if(typeof val != "string"){
// skip non-serializable values
continue;
}
output.push(newLine + nextIndent + keyStr + ":" + sep + val);
}
}
return "{" + output.join("," + sep) + newLine + _indentStr + "}";
}else if(typeof it == "function" && dojox.json.ref.serializeFunctions){
return it.toString();
}
return dojo.toJson(it); // use the default serializer for primitives
}
var json = serialize(it,'$','');
for(i in paths) {// cleanup the temporary path-generated ids
delete paths[i].__id;
}
return json;
};
dojox.json.ref.useRefs=false;
dojox.json.ref.serializeFunctions=false;
