Develop Reference

Parsting tree with getJson

I have a JSON file with order data. The JSON file is formatted like this:
{
"orders": [
{"name": "Peter", "email": "peter#aol.com"}
{"name": "David", "email": "david#aol.com"}
{ "name": "George", "email": "george#aol.com"}
]
}
As you can see; all the data is part of a branch called "orders" and then each order is its own branch, but the branch doesn't have a name.
I am trying to generate a list of the "name"s in the dataset.
With a simplified dataset, I would do something like:
$(data).each(function(i, name){
$('#namesText').append($("li")
.append($("li").append(name.name))
});
})
This however doesn't work as the data is not in the first level of the tree.
My question is, how do I go down levels when the levels don't have a name?

This sounds like a DFS problem where each object has keys that can possibly be a primitive data type or another object. Since the name field could be at any level in this given constraint you need to solve for, I would say use DFS algo where it traverses each key in the object and if there is another object, look into that until you find a name field. Better solution is to redesign the data structure so that you are guaranteed to know which level and location the name field is at any time.

If you want a list of the name property from the elements of the orders array you could use Array.map:
const names = myJson.orders.map(o => o.name);

Try
namesText.innerHTML= data.orders.map(p=>`<li>${escape(p.name)}</li>`).join``
var data = {
"orders": [
{
"name": "Peter",
"email": "peter#aol.com",
},
{
"name": "David",
"email": "david#aol.com",
},
{
"name": "George",
"email": "george#aol.com",
}
]
}
namesText.innerHTML= data.orders.map(p=>`<li>${escape(p.name)}</li>`).join``
<ul id="namesText"></ul>

JSON list optimization

I want to create a JSON API that returns a list of objects. Each object has an id, a name and some other information. API is consumed using JavaScript.
The natural options for my JSON output seems to be:
"myList": [
{
"id": 1,
"name": "object1",
"details": {}
},
{
"id": 2,
"name": "object2",
"details": {}
},
{
"id": 3,
"name": "object3",
"details": {}
},
]
Now let's imagine that I use my API to get all the objects but want to first do something with id2 then something else with id1 and id3.
Then I may be interested to be able to directly get the object for a specific id:
"myList": {
"1": {
"name": "object1",
"details": {}
},
"2": {
"name": "object2",
"details": {}
},
"3": {
"name": "object3",
"details": {}
},
}
This second option may be less natural when somewhere else in the code I want to simply loop through all the elements.
Is there a good practice for these use cases when the API is used for both looping through all elements and sometime using specific elements only (without doing a dedicated call for each element)?

In your example you've changed the ID value from 1 to id1. This would make operating on the data a bit annoying, because you have to add and remove id all the time.
If you didn't do that, and you were relying on the sorted order of the object, you may be in for a surprise, depending on JS engine:
var source = JSON.stringify({z: "first", a: "second", 0: "third"});
var parsed = JSON.parse(source);
console.log(Object.keys(parsed));
// ["0", "z", "a"]
My experience is to work with arrays on the transport layer and index the data (i.e. convert array to map) when required.

Indexing array values in an object in an IndexedDB

For a Chrome app, wich stores data in IndexedDB, i have a object like this:
var simplifiedOrderObject = {
"ordernumber": "123-12345-234",
"name": "Mr. Sample",
"address": "Foostreet 12, 12345 Bar York",
"orderitems": [
{
"item": "brush",
"price": "2.00"
},
{
"item": "phone",
"price": "30.90"
}
],
"parcels": [
{
"service": "DHL",
"track": "12345"
},
{
"service": "UPS",
"track": "3254231514"
}
]
}
If i store the hole object in an objectStore, can i use an index for "track", which can be contained multiple times in each order object?
Or is it needed or possibly better/faster to split each object into multiple objectStores like know from relational DBs:
order
orderitem
parcel
The solution should also work in a fast way with 100.000 or more objects stored.

Answering my own question: I have made some tests now. It looks like it is not possible to do this with that object in only 1 objectStore.
An other example object which would work:
var myObject = {
"ordernumber": "123-12345-234",
"name": "Mr. Sample",
"shipping": {"method": "letter",
"company": "Deutsche Post AG" }
}
Creating an index will be done by:
objectStore.createIndex(objectIndexName, objectKeypath, optionalObjectParameters);
With setting objectKeypath it is possible to address a value in the main object like "name":
objectStore.createIndex("name", "name", {unique: false});
It would also be possible to address a value form a subobject of an object like "shipping.method":
objectStore.createIndex("shipping", "shipping.method", {unique: false});
BUT it is not possible to address values like the ones of "track", which are contained in objects, stored in an array. Even something like "parcels[0].track" to get the first value as index does not work.
Anyhow, it would be possible to index all simple elements of an array (but not objects).
So the following more simple structure would allow to create an index entry for each parcelnumber in the array "trackingNumbers":
var simplifiedOrderObject = {
"ordernumber": "123-12345-234",
"name": "Mr. Sample",
"address": "Foostreet 12, 12345 Bar York",
"orderitems": [
{
"item": "brush",
"price": "2.00"
},
{
"item": "phone",
"price": "30.90"
}
],
"trackingNumbers": ["12345", "3254231514"]
}
when creating the index with multiEntry set to true:
objectStore.createIndex("tracking", "trackingNumbers", {unique: false, multiEntry: true});
Anyhow, the missing of the possibility to index object values in arrays, makes using indexedDB really unneeded complicated. It's a failure in design. This forces the developer to do things like in relational DBs, while lacking all the possibilities of SQL. Really bad :(

Populate AngularJS {{expression}} within ng-repeat using a second array

I'm completely rebuilding my website (originally hacked together with Wordpress) using Laravel and AngularJS. It's been a massive learning experience and I think I'm nearly there but for one problem.
On my site 'schemes' (or courses) are made up of 'units' which are made up of 'lessons'. Retrieving this data is fine, using Eloquent I retrieve valid JSON like this made up example...
[
{
"id": "1", //Scheme Id
"title": "Sports",
"description": "This is a Sports course!",
"units": [
{
"id": "1",
"title": "Tennis",
"lessons": [
{
"id": "6",
"title": "Serving"
},
{
"id": "7",
"title": "Hitting the ball with top-spin"
}
]
},
{
"id": "2",
"title": "Athletics",
"lessons": [
{
"id": "1",
"title": "Long Jump"
},
{
"id": "2",
"title": "Hurdling Technique"
}
]
},
{
"id": "4",
"title": "Golf",
"lessons": [
{
"id": "4",
"title": "Pitching"
},
{
"id": "5",
"title": "Putting"
}
]
}
]
}
....
]
Separately I have a simple array of completed lesson ids for a particular user like this...
[2, 6, 8, 9] ///User has completed lessons with ids of 2,6,8 and 9
In my view I'm using nested ng-repeat loops like so...
...
<div ng-controller="SchemesController">
<div ng-repeat="scheme in schemes">
<h1>{{scheme.title}}</h1>
<div ng-repeat="unit in scheme.units">
<h3>{{unit.title}}</h3>
<div ng-repeat="lesson in unit.lessons">
<div>{{lesson.title}}: {{status}}</div>
</div>
</div>
</div>
</div><!--[end of ng-controller="SchemesController"]-->
....
SchemesController (v simple!) looks like this...
var app = angular.module('schemesApp', []);
app.controller('SchemesController', function($scope){
$scope.schemes=jsonData;
});
The problem is I have no idea how to populate the {{status}} field which I want to state simply 'Complete' or 'Incomplete. I investigated whether I could somehow add this info to my original array like this...
"lessons": [
{
"id": "6",
"title": "Serving",
"status": "Complete" //populated somehow
},
{
"id": "7",
"title": "Hitting the ball with top-spin",
}
]
but I got nowhere slowly. Is there a way to do this (I've played around with underscore.js and felt this could help?).
Or do I populate {{status}} from creating and calling a javascript function?!?
ANY help that anyone could offer would be incredible. I'm a school teacher and for some sadistic reason I find a bit of programming/web design a fun use of my spare time so I apologise if this is a stupid question. THANKS in advance!!!
btw if anyone has a better 'title' for this question then please let me know.

I'm assuming you don't need to persist the status back to the database...
This is where you're having the problem:
<div>{{lesson.title}}: {{status}}</div>
You really don't need to store the status in your data model, because it's just used for presentation purposes.
Let's say your array of completed lessons is defined like this:
$scope.completedLessons = [1, 2, 3, 4, 5] // Or however you'd assign it
You need to create a function in your scope like this:
$scope.isLessonCompleted = function(lessonId) {
return $scope.completedLessons.indexOf(lessonId) > -1;
};
Then you need to change the html from above to this:
<div>{{lesson.title}}: {{isLessonCompleted(lesson.id) && 'Complete' || 'Incomplete'}}</div>

If lessons are also a model and each lesson should have a status, which isn't a column/field in your table but is something you'll add logic to determine, you could add a custom model accessor by adding the following to your models/Lesson.php:
// Append custom accessor attributes
protected $appends = ['status'];
public function getStatusAttribute() {
// Add logic here
return 'Complete';
}
This way, when you use Eloquent to retrieve your data, you'll also see a status attribute as part of the object, so you could then access it as usual $lesson->status (PHP) or lesson.status (JS).
For more information, see the official Laravel documentation on accessors and mutators

How to create Backbone collection from following json array?

I am getting a following JSON(/users.json) which contains users:
[
[
{ "id": "43343", "project_id": "1", "username": "Amy" }
{ "id": "34244", "project_id": "1", "username": "Tommy" }
],
[
{ "id": "76575", "project_id": "2", "username": "Izzy" }
{ "id": "13322", "project_id": "2", "username": "Sam" }
],
{ "id": "09983", "project_id": "3", "username": "Max" }
]
When project has one user I get one user hash which is not in array.
I would like to build a Backbone collection with all users. How to do that?

You provide an array of arrays of users. So to fetch all users in the init method, you can give it data but as an array of users, i.e. you will flatten this original array of arrays once with underscore flatten method :
data = _(data).flatten(true);
Then the collection constructor will natively understand your json array.
But maybe you already do this transformation in the fetching method and this is not the problem you are facing..

If you have defined a collection (say userCollection) with a user model you should be able to simply do something like this:
var col;
$.getJSON("/users.json", function(data) {
col = new userCollection(data);
});
This would more likely be done in the fetch function of the collection, but the principle here is that you can pass an array of objects to a collection and it will marshal all from json to backbone models.