I want to do:
properties.email.value without triggering an error like: Can't read 'value' of 'undefined'
However, I don't want to do:
properties.email && properties.email.value and I don't want to use an helper, something like: get(properties, 'email.value').
I really want to keep the syntax properties.email.value
I can solve this by doing:
Object.defineProperty(properties, 'email', {
get: () => properties.email && properties.email.value,
enumerable: true,
configurable: true
});
Now the getter is in charge of doing my safety check. Perfect.
But I also want to be able to do properties.name.value safely.
But as the properties object comes from the API (json), I don't know the full list of properties possible.
So, is there a way to use this "magical" get syntax for any prop access like: properties[ANYTHING].value ?
OK, I've got something like this.
But you must create properties that way.
Hope this help :)
var properties = {
phone : {
value: "123456789"
}
}
var handler = {
get: function(target, name) {
return target.hasOwnProperty(name) ? target[name] : {};
}
};
var new_properties = new Proxy(properties, handler);
console.log("phone.value = " + new_properties.phone.value);
console.log("email.value = " + new_properties.email.value);
new_properties.email = {
value: 1
};
console.log("email.value after assign = " + new_properties.email.value);
The document reference here.
Edited
Even if the original properties object is unknown, this kind of usage works as well.
You could use a Proxy and get known properties and a custom result for unknow properties.
For changing properties, you could take the same approach and set the value.
var properties = { email: { value: 'foo#example.com' } },
proxy = new Proxy(
properties,
{
get: function(target, prop, receiver) {
if (prop in target) {
return target[prop] && target[prop].value
} else {
return;
}
},
set: function(target, prop, value) {
if (prop in target) {
target[prop].value = value;
} else {
target[prop] = { value };
}
}
}
);
console.log(proxy.email);
console.log(proxy.bar);
proxy.email = '41';
console.log(proxy.email);
I can't believe I'm doing this...
var wordlength = 7;
var alphabet="abcdefghijklmnopqrstuvwxyz";
alphabet += alphabet.toUpperCase() + "0123456789_";
var alen = alphabet.length;
var buildWord = function(number){
if(number===0){
return '';
}
return alphabet[number%alen]+buildWord(Math.floor(number/alen));
};
var total = Math.pow(alen, wordlength);
for(var i = 1; i<total; i++){
var w = buildWord(i);
if(isNaN(w[0]) && Object.prototype[w]===undefined){
Object.prototype[w]={};
}
}
Related
I have a JSON object that looks a bit like this:
{
name: 'test',
details: {
description: 'This is the long description',
shortDescription: 'This is the short description (ironically longer than the description!)'
}
}
Obviously the real object is a lot more complicated than this example, but I have omitted the details because they will only complicate the question.
So, with this object, I have a function that tries to get the value of the property, it looks like this:
// Private function for matching fields
var _matchField = function (item, filter) {
// Our variables
var text = item[filter.field],
values = filter.expression.split(',');
// If we have any text
if (text) {
// Loop through our values
angular.forEach(values, function (value) {
console.log(text);
console.log(value);
// See if we have a match
if (text.toLowerCase().indexOf(value.toLowerCase()) > -1) {
// We have found a match
return true;
}
});
}
// We have found no matches
return false;
}
The issue is the line:
var text = item[filter.field],
If the property was just the name then item['name'] would work with the above object. But if I want to get the description; item['details.descrption'] doesn't work.
So I need a function that will allow me to specify a property name and it will find the property and return its value.
But before I try to write one, I was hoping there might be a simple solution that someone has come across.
you can write your custom function for this
function getProperty(json, field) {
if (json == null || field == null) {
return null;
}
var value = json;
var fields = field.split(".");
for (var i = 0; i < fields.length; i++) {
value = value[fields[i]];
if (value == null) {
return null;
}
}
return value;
}
check this plnkr example https://plnkr.co/edit/8Ayd9wnh1rJh1ycx5R1f?p=preview
You can split the reference to the object and use a function for getting the right nested object/value.
function getValue(o, p) {
if (typeof p === 'string') {
p = p.split('.')
}
return p.length ? getValue(o[p.shift()], p) : o;
}
var item = { name: 'test', details: { description: 'This is the long description', shortDescription: 'This is the short description (ironically longer than the description!)' } };
document.write(getValue(item, 'details.description'));
I solved this by creating this function:
// Private function to get the value of the property
var _getPropertyValue = function (object, notation) {
// Get all the properties
var properties = notation.split('.');
// If we only have one property
if (properties.length === 1) {
// Return our value
return object[properties];
}
// Loop through our properties
for (var property in object) {
// Make sure we are a property
if (object.hasOwnProperty(property)) {
// If we our property name is the same as our first property
if (property === properties[0]) {
// Remove the first item from our properties
properties.splice(0, 1);
// Create our new dot notation
var dotNotation = properties.join('.');
// Find the value of the new dot notation
return _getPropertyValue(object[property], dotNotation);
}
}
}
};
Is it possible to create an array that will only allow objects of a certain to be stored in it? Is there a method that adds an element to the array I can override?
Yes you can, just override the push array of the array (let's say all you want to store are numbers than do the following:
var myArr = [];
myArr.push = function(){
for(var arg of arguments) {
if(arg.constructor == Number) Array.prototype.push.call(this, arg);
}
}
Simply change Number to whatever constructor you want to match. Also I would probably add and else statement or something, to throw an error if that's what you want.
UPDATE:
Using Object.observe (currently only available in chrome):
var myArr = [];
Array.observe(myArr, function(changes) {
for(var change of changes) {
if(change.type == "update") {
if(myArr[change.name].constructor !== Number) myArr.splice(change.name, 1);
} else if(change.type == 'splice') {
if(change.addedCount > 0) {
if(myArr[change.index].constructor !== Number) myArr.splice(change.index, 1);
}
}
}
});
Now in ES6 there are proxies which you should be able to do the following:
var myArr = new Proxy([], {
set(obj, prop, value) {
if(value.constructor !== Number) {
obj.splice(prop, 1);
}
//I belive thats it, there's probably more to it, yet because I don't use firefox or IE Technical preview I can't really tell you.
}
});
Not directly. But you can hide the array in a closure and only provide your custom API to access it:
var myArray = (function() {
var array = [];
return {
set: function(index, value) {
/* Check if value is allowed */
array[index] = value;
},
get: function(index) {
return array[index];
}
};
})();
Use it like
myArray.set(123, 'abc');
myArray.get(123); // 'abc' (assuming it was allowed)
I am trying to recursively build an object with a tree of properties based on a MongoDB-ish selector "top.middle.bottom". There are some underscorejs helpers as well:
function setNestedPropertyValue(obj, fields, val) {
if (fields.indexOf(".") === -1) {
// On last property, set the value
obj[fields] = val;
return obj; // Recurse back up
} else {
var oneLevelLess = _.first(fields.split("."));
var remainingLevels = _.rest(fields.split(".")).join(".");
// There are more property levels remaining, set a sub with a recursive call
obj[oneLevelLess] = setNestedPropertyValue( {}, remainingLevels, val);
}
}
setNestedPropertyValue({}, "grandpaprop.papaprop.babyprop", 1);
Desired:
{
grandpaprop: {
papaprop: {
babyprop: 1
}
}
}
Outcome:
undefined
Helps and hints would be appreciated.
Instead of recursion I would choose for an iterative solution:
function setNestedPropertyValue(obj, fields, val)
{
fields = fields.split('.');
var cur = obj,
last = fields.pop();
fields.forEach(function(field) {
cur[field] = {};
cur = cur[field];
});
cur[last] = val;
return obj;
}
setNestedPropertyValue({}, "grandpaprop.papaprop.babyprop", 1);
EDIT
And here is another version thanks to the suggestions by Scott Sauyet:
function setPath(obj, [first, ...rest], val) {
if (rest.length == 0) {
return {...obj, [first]: val}
}
let nestedObj = obj[first] || {};
return {...obj, [first]: setPath(nestedObj, rest, val)};
}
function setNestedPropertyValue(obj, field, val) {
return setPath(obj, field.split('.'), val);
}
// example
let test_obj = {};
test_obj = setNestedPropertyValue(test_obj, "foo.bar.baz", 1);
test_obj = setNestedPropertyValue(test_obj, "foo.bar.baz1", 1);
// will output {"foo":{"bar":{"baz":1,"baz1":1}}}, while in the original version only "baz1" will be set
console.log(JSON.stringify(test_obj));
It's plain javascript
It only appends properties and will not override a top level object
setNestedPropertyValue() does not mutate the passed object (although keep in mind it only returns a shallow copy of the object, so some properties may be shared references between the original object and the new one)
I know this is old, but I needed exactly that kind of function and wasn't happy with the implementation, so here is my version:
function setNestedPropertyValue(obj, field, val) {
if (field.indexOf(".") === -1) {
obj[field] = val;
} else {
let fields = field.split(".");
let topLevelField = fields.shift();
let remainingFields = fields.join(".");
if (obj[topLevelField] == null) {
obj[topLevelField] = {};
}
setNestedPropertyValue(obj[topLevelField], remainingFields, val);
}
}
// example
let test_obj = {};
setNestedPropertyValue(test_obj, "foo.bar.baz", 1);
setNestedPropertyValue(test_obj, "foo.bar.baz1", 1);
// will output {"foo":{"bar":{"baz":1,"baz1":1}}}, while in the original version only "baz1" will be set
console.log(JSON.stringify(test_obj));
It's plain javascript
It only appends properties and will not override a top level object
setNestedPropertyValue() does not return the object so it is clear that it mutates the passed object
As mentioned by Jack in the question, I was not returning my object in the last line in the else statement. By adding this, it is now working:
obj[oneLevelLess] = setNestedPropertyValue( {}, remainingLevels, val);
return obj; // Add this line
}
I am looking for an efficient way to translate my Ember object to a json string, to use it in a websocket message below
/*
* Model
*/
App.node = Ember.Object.extend({
name: 'theName',
type: 'theType',
value: 'theValue',
})
The websocket method:
App.io.emit('node', {node: hash});
hash should be the json representation of the node. {name: thename, type: theType, ..}
There must be a fast onliner to do this.. I dont want to do it manualy since i have many attributes and they are likely to change..
As stated you can take inspiration from the ember-runtime/lib/core.js#inspect function to get the keys of an object, see http://jsfiddle.net/pangratz666/UUusD/
App.Jsonable = Ember.Mixin.create({
getJson: function() {
var v, ret = [];
for (var key in this) {
if (this.hasOwnProperty(key)) {
v = this[key];
if (v === 'toString') {
continue;
} // ignore useless items
if (Ember.typeOf(v) === 'function') {
continue;
}
ret.push(key);
}
}
return this.getProperties.apply(this, ret);
}
});
Note, since commit 1124005 - which is available in ember-latest.js and in the next release - you can pass the ret array directly to getProperties, so the return statement of the getJson function looks like this:
return this.getProperties(ret);
You can get a plain JS object (or hash) from an Ember.Object instance by calling getProperties() with a list of keys.
If you want it as a string, you can use JSON.stringify().
For example:
var obj = Ember.Object.create({firstName: 'Erik', lastName: 'Bryn', login: 'ebryn'}),
hash = obj.getProperties('firstName', 'lastName'), // => {firstName: 'Erik', lastName: 'Bryn'}
stringHash = JSON.stringify(hash); // => '{"firstName": "Erik", "lastName": "Bryn"}'
I have also been struggling with this. As Mirko says, if you pass the ember object to JSON.stringify you will get circular reference error. However if you store the object inside one property and use stringify on that object, it works, even nested subproperties.
var node = Ember.Object.create({
data: {
name: 'theName',
type: 'theType',
value: 'theValue'
}
});
console.log(JSON.stringify(node.get('data')));
However, this only works in Chrome, Safari and Firefox. In IE8 I get a stack overflow so this isn't a viable solution.
I have resorted to creating JSON schemas over my object models and written a recursive function to iterate over the objects using the properties in the schemas and then construct pure Javascript objects which I can then stringify and send to my server. I also use the schemas for validation so this solution works pretty well for me but if you have very large and dynamic data models this isn't possible. I'm also interested in simpler ways to accomplish this.
I modifed #pangratz solution slightly to make it handle nested hierarchies of Jsonables:
App.Jsonable = Ember.Mixin.create({
getJson: function() {
var v, json = {};
for (var key in this) {
if (this.hasOwnProperty(key)) {
v = this[key];
if (v === 'toString') {
continue;
}
if (Ember.typeOf(v) === 'function') {
continue;
}
if (App.Jsonable.detect(v))
v = v.getJson();
json[key] = v;
}
}
return json;
}
});
App.io.emit('node', {node: node.toJSON()});
Or if you have an ID property and want to include it:
App.io.emit('node', {node: node.toJSON({includeId: true})});
Will this work for you?
var json = JSON.stringify( Ember.getMeta( App.node, 'values') );
The false is optional, but would be more performant if you do not intend to modify any of the properties, which is the case according to your question. This works for me, but I am wary that Ember.meta is a private method and may work differently or not even be available in future releases. (Although, it isn't immediately clear to me if Ember.getMeta() is private). You can view it in its latest source form here:
https://github.com/emberjs/ember.js/blob/master/packages/ember-metal/lib/utils.js
The values property contains only 'normal' properties. You can collect any cached, computed properties from Ember.meta( App.node, false ).cached. So, provided you use jQuery with your build, you can easily merge these two objects like so:
$.extend( {}, Ember.getMeta(App.node, 'values'), Ember.getMeta(App.node, 'cache') );
Sadly, I haven't found a way to get sub-structures like array properties in this manner.
I've written an extensive article on how you can convert ember models into native objects or JSON which may help you or others :)
http://pixelchild.com.au/post/44614363941/how-to-convert-ember-objects-to-json
http://byronsalau.com/blog/convert-ember-objects-to-json/
I modified #Kevin-pauli solution to make it works with arrays as well:
App.Jsonable = Ember.Mixin.create({
getJson: function() {
var v, json = {}, inspectArray = function (aSome) {
if (Ember.typeof(aSome) === 'array') {
return aSome.map(inspectArray);
}
if (Jsonable.detect(aSome)) {
return aSome.getJson();
}
return aSome;
};
for (var key in this) {
if (this.hasOwnProperty(key)) {
v = this[key];
if (v === 'toString') {
continue;
}
if (Ember.typeOf(v) === 'function') {
continue;
}
if (Ember.typeOf(v) === 'array') {
v = v.map(inspectArray);
}
if (App.Jsonable.detect(v))
v = v.getJson();
json[key] = v;
}
}
return json;
}
});
I also made some further modification to get the best of both worlds. With the following version I check if the Jsonable object has a specific property that informs me on which of its properties should be serialized:
App.Jsonable = Ember.Mixin.create({
getJson: function() {
var v, json = {}, base, inspectArray = function (aSome) {
if (Ember.typeof(aSome) === 'array') {
return aSome.map(inspectArray);
}
if (Jsonable.detect(aSome)) {
return aSome.getJson();
}
return aSome;
};
if (!Ember.isNone(this.get('jsonProperties'))) {
// the object has a selective list of properties to inspect
base = this.getProperties(this.get('jsonProperties'));
} else {
// no list given: let's use all the properties
base = this;
}
for (var key in base) {
if (base.hasOwnProperty(key)) {
v = base[key];
if (v === 'toString') {
continue;
}
if (Ember.typeOf(v) === 'function') {
continue;
}
if (Ember.typeOf(v) === 'array') {
v = v.map(inspectArray);
}
if (App.Jsonable.detect(v))
v = v.getJson();
json[key] = v;
}
}
return json;
}
});
I am using this little tweak and I am happy with it. I hope it'll help others as well!
Thanks to #pangratz and #Kevin-Pauli for their solution!
Here I take #leo, #pangratz and #kevin-pauli solution a little step further. Now it iterates not only with arrays but also through has many relationships, it doesn't check if a value has the type Array but it calls the isArray function defined in Ember's API.
Coffeescript
App.Jsonable = Em.Mixin.create
getJson: ->
jsonValue = (attr) ->
return attr.map(jsonValue) if Em.isArray(attr)
return attr.getJson() if App.Jsonable.detect(attr)
attr
base =
if Em.isNone(#get('jsonProperties'))
# no list given: let's use all the properties
this
else
# the object has a selective list of properties to inspect
#getProperties(#get('jsonProperties'))
hash = {}
for own key, value of base
continue if value is 'toString' or Em.typeOf(value) is 'function'
json[key] = jsonValue(value)
json
Javascript
var hasProp = {}.hasOwnProperty;
App.Jsonable = Em.Mixin.create({
getJson: function() {
var base, hash, hashValue, key, value;
jsonValue = function(attr) {
if (Em.isArray(attr)) {
return attr.map(jsonValue);
}
if (App.Jsonable.detect(attr)) {
return attr.getJson();
}
return attr;
};
base = Em.isNone(this.get('jsonProperties')) ? this : this.getProperties(this.get('jsonProperties'));
json = {};
for (key in base) {
if (!hasProp.call(base, key)) continue;
value = base[key];
if (value === 'toString' || Em.typeOf(value) === 'function') {
continue;
}
json[key] = jsonValue(value);
}
return json;
}
});
Ember Data Model's object counts with a toJSON method which optionally receives an plain object with includeId property used to convert an Ember Data Model into a JSON with the properties of the model.
https://api.emberjs.com/ember-data/2.10/classes/DS.Model/methods/toJSON?anchor=toJSON
You can use it as follows:
const objects = models.map((model) => model.toJSON({ includeId: true }));
Hope it helps. Enjoy!
I have:
fixed and simplified code
added circular reference prevention
added use of get of value
removed all of the default properties of an empty component
//Modified by Shimon Doodkin
//Based on answers of: #leo, #pangratz, #kevin-pauli, #Klaus
//http://stackoverflow.com/questions/8669340
App.Jsonable = Em.Mixin.create({
getJson : function (keysToSkip, visited) {
//getJson() called with no arguments,
// they are to pass on values during recursion.
if (!keysToSkip)
keysToSkip = Object.keys(Ember.Component.create());
if (!visited)
visited = [];
visited.push(this);
var getIsFunction;
var jsonValue = function (attr, key, obj) {
if (Em.isArray(attr))
return attr.map(jsonValue);
if (App.Jsonable.detect(attr))
return attr.getJson(keysToSkip, visited);
return getIsFunction?obj.get(key):attr;
};
var base;
if (!Em.isNone(this.get('jsonProperties')))
base = this.getProperties(this.get('jsonProperties'));
else
base = this;
getIsFunction=Em.typeOf(base.get) === 'function';
var json = {};
var hasProp = Object.prototype.hasOwnProperty;
for (var key in base) {
if (!hasProp.call(base, key) || keysToSkip.indexOf(key) != -1)
continue;
var value = base[key];
// there are usual circular references
// on keys: ownerView, controller, context === base
if ( value === base ||
value === 'toString' ||
Em.typeOf(value) === 'function')
continue;
// optional, works also without this,
// the rule above if value === base covers the usual case
if (visited.indexOf(value) != -1)
continue;
json[key] = jsonValue(value, key, base);
}
visited.pop();
return json;
}
});
/*
example:
DeliveryInfoInput = Ember.Object.extend(App.Jsonable,{
jsonProperties: ["title","value","name"], //Optionally specify properties for json
title:"",
value:"",
input:false,
textarea:false,
size:22,
rows:"",
name:"",
hint:""
})
*/
Ember.js appears to have a JSON library available. I hopped into a console (Firebug) on one the Todos example and the following worked for me:
hash = { test:4 }
JSON.stringify(hash)
So you should be able to just change your line to
App.io.emit('node', { node:JSON.stringify(hash) })
If I have the following:
var myObj = { "Foo":{"prop1":"abc", "prop2":123 }, "Bar":{"prop1":"def", "prop2":456 } };
Is there a quick and safe way to modify the object such that it becomes:
{ "Foo":{"prop1":"abc", "prop2":123 }, "Bar":{"PROP1":"def", "PROP2":456 } }
I'd like to change the casing of the property names of the Bar property on-the-fly. Is this possible?
Yes, it is. try this code
var myObjBar = myObj['Bar'];
for (p in myObjBar) {
if (myObjBar.hasOwnProperty(p)) {
var v = myObjBar[p],
k = p.toUpperCase();
delete myObjBar[p];
myObjBar[k] = v;
}
}