Develop Reference

Generating components through iteration

Something weird is going on:
This is my initial state (a .js file)
import moment from 'moment';
let date = moment();
var previousDate = moment("2015-12-25");
export const projects = [
{
"id": 0,
"metadata": {
"fields":
[{
"id": 1,
"order": 1,
"name": "Name",
"value": "Collection 1"
},
{
"id": 2,
"order": 2,
"name": "Created On",
"value": date
},
{
"id": 3,
"order": 3,
"name": "Last Modified On",
"value": previousDate
},
{
"id": 4,
"order": 4,
"name": "Status",
"value": "Filed"
}],
"tags":
[{
"id": 1,
"order": 1,
"value": "tag1"
},
{
"id": 2,
"order": 2,
"value": "tag2"
},
{
"id": 3,
"order": 3,
"value": "tag3"
},
{
"id": 4,
"order": 4,
"value": "tag4"
}]
}
}
This is ProjectsList.js:
import React from 'react';
import Project from './Project';
import { projects } from 'initialState';
export default (props) => {
return(
<div className="projectsList">
{projects.map(project => (
<article key={project.id}><Project fields={project.metadata.fields} /></article>
))}
</div>
)
}
And this one's Project.js:
import React from 'react';
export default (props) => {
return(
<ul className="fields">
{props.fields.map(field => <li key={field.id}>{field.name}</li>) }
</ul>
)
}
I am trying to render a bunch of projects in a list, and every project contains a bunch of metadata key-value pairs that it shows.
So basically, the wiring does not matter, it all works fine.
Except for this:
If you look up at the initial state file (first one up there), there is an array of multiple objects in fields. Each object shows 4 key-value pairs
id
order
name
value
Now, in Project.js, the line where I go
{props.fields.map(field => <li key={field.id}>{field.name}</li>) }
looks like I can switch the {field.name} for {field.id}, to show the id in text. Or I can go {field.order}, to display the order.
But weirdly enough, if I want to show the actual value of the field, like so {field.value}, it throws.
invariant.js?4599:38
Uncaught Invariant Violation: Objects are not valid as a React child (found: Mon Jun 20 2016 21:40:33 GMT-0400). If you meant to render a collection of children, use an array instead or wrap the object using createFragment(object) from the React add-ons. Check the render method of `StatelessComponent`.
I even went as far (sigh) as changing the string value in every fields to val, juste to make sure value wasn't some kind of a reserved word.
Still threw.
Anybody can help me understand what I have done wrong, here?
Thanks Guys.

You are assigning to variable values to the value property in your state file, which are most likely not strings, but objects:
export const projects = [{
"id": 0,
"metadata": {
"fields":
[
...
{
"id": 2,
"order": 2,
"name": "Created On",
"value": date // one
},
{
"id": 3,
"order": 3,
"name": "Last Modified On",
"value": previousDate // and another one
},
...
]
...
}
}

If typeof children returns "object" (and children is neither an array, nor a ReactElement), it throws:
https://github.com/facebook/react/blob/dc6fc8cc0726458a14f0544a30514af208d0098b/src/shared/utils/traverseAllChildren.js#L169
Here's a simplest example to demonstrate this:
const IllegalComponent = () => <span>{{}}</span>
You are supposed to supply a string (or number) so that React could inline that as the children in <li>. Children should be something that's renderable and implements ReactNode.
If the children is an object, React would not know how to render it. You should explicitly convert the value to String.
Try this to see if it works:
{props.fields.map(field => <li key={field.id}>{field.value.toString()}</li>) }

elasticsearch autosuggest returning tricky JSON

I'm running a node.js server that sends queries to an elasticsearch instance. Here is an example of the JSON returned by the query:
{
"took": 2,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 9290,
"max_score": 0,
"hits": []
},
"suggest": {
"postSuggest": [
{
"text": "a",
"offset": 0,
"length": 1,
"options": [
{
"text": "Academic Librarian",
"score": 2
},
{
"text": "Able Seamen",
"score": 1
},
{
"text": "Academic Dean",
"score": 1
},
{
"text": "Academic Deans-Registrar",
"score": 1
},
{
"text": "Accessory Designer",
"score": 1
}
]
}
]
}
}
I need to create an array containing each job title as a string. I've run into this weird behavior that I can't figure out. Whenever I try to pull values out of the JSON, I can't go below options or everything comes back as undefined.
For example:
arr.push(results.suggest.postSuggest) will push just what you'd expect: all the stuff inside postSuggest.
arr.push(results.suggest.postSuggest.options) will come up as undefined even though I can see it when I run it without .options. This is also true for anything below .options.
I think it may be because .options is some sort of built-in function that acts on variables, so instead of seeing options as JSON and is instead trying to run a function on results.suggest.postSuggest

arr.push(results.suggest.postSuggest.options)
postSuggest is an array of object.options inside postSuggest is also array of object. So first you need to get postSuggest by postSuggest[0] and then
postSuggest[0].options to get array of options
This below snippet can be usefule
var myObj = {..}
// used jquery just to demonstrate postSuggest is an Array
console.log($.isArray(myObj.suggest.postSuggest)) //return true
var getPostSuggest =myObj.suggest.postSuggest //Array of object
var getOptions = getPostSuggest[0].options; // 0 since it contain only one element
console.log(getOptions.length) ; // 5 , contain 5 objects
getOptions.forEach(function(item){
document.write("<pre>Score is "+ item.score + " Text</pre>")
})
Jsfiddle

check json object exist to be save into localstorage

[
{
"id": 1,
"title": "my Item",
"body": ""
},
{
"id": 2,
"title": "my Item 2",
"body": ""
},
{
"id": 3,
"title": "my Item 3",
"body": ""
}
]
Is above json structure good for storing says users viewed books? I have other key like users' setting so I try to nested/group things to be neater. My question is how can I check an object with value exist or not so I won't insert duplicated data. How to check the id 2 is existed in this case? Do I have to loop?

Do I have to loop?
Yes you have to loop ( or use a method which will do it) :
var idToCheck="id";
var valToCheck=2;
var a = your array...
var wasFound=false;
a.forEach(function(entry) {
if (entry[idToCheck]==valToCheck)
{
wasFound=true;
return;
}
});
//do whatever with `wasFound`.
http://jsbin.com/jigefamiqu/1/edit

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

Javascript looping through elements and adding to table

I'm having trouble finding a solution that will help me loop through a bunch of elements and putting the chosen values into a table. I've been able to withdraw some values but the method isn't dynamic.
Here is an example:
var Table = {
"credit": {
"link": "site link",
"logoUrl": "logo url",
"message": "message"
},
"groups": [
{
"labels": [
{
"name": "Western Conference",
"type": "conference"
},
{
"name": "Central Division",
"type": "division"
}
],
"standings": [
{
"stats": [
{
"name": "gp",
"value": 20
},
{
"name": "w",
"value": 17
},
{
"name": "l",
"value": 0
},
{
"name": "gf",
"value": 64
},
{
"name": "ga",
"value": 37
},
{
"name": "gd",
"value": 27
},
{
"name": "pts",
"value": 37
}
],
"team": {
"id": 12345,
"link": "team link",
"name": "team name",
"shortName": "team"
}
},
This is the structure of the elements. So far I've used this:
document.getElementById("sGamesPlayed").innerHTML=Table.groups[0].standings[0].stats[0].value;
to withdraw values. However there are more teams, stats and divisions so I would need some kind of loop to go through the elements and put the into a dynamic table.

I would consider you to look at http://underscorejs.org/.
it provides a bunch of utility functions that could help you,
for example, _.each() helps you loop through JSON properties.
for the sample objects you've given (after completing the missing brackets at the end),
_.each(Table.groups[0].standings[0].stats, function(stats){
console.log(stats['name']+","+stats['value'])
})
gives me:
gp,20
w,17
l,0
gf,64
ga,37
gd,27
pts,37
how it works is that you provide the object you want as the first argument and the function that you give as the second argument will be called with each element of the first argument (Assuming it is a list).
I would also urge you to look at underscore templating that you can use to render your table where i put the console.log :
http://net.tutsplus.com/tutorials/javascript-ajax/getting-cozy-with-underscore-js/
http://scriptble.com/2011/01/28/underscore-js-templates/

I guess your question is about filtering the values of the array standings. In order to do that you can use the jQuery grep function (if you want to use jQuery).
For example you can write:
var arr = $.grep(Table.groups[0].standings[0].stats, function(d){return d.value>25})
Which will give
arr = [{"name": "gf","value": 64}, {"name": "ga", "value": 37},{"name": "gd", "value": 27},{"name": "pts", "value": 37}]
If this is not what you meant, can you please create a jsFiddle with a sample of what you want?

Depending on what you want to do with the results, you can go over the object using a scheme like:
var groups, standings, stats, value;
groups = Table.groups;
// Do stuff with groups
for (var i=0, iLen=groups.length; i<iLen; i++) {
standings = groups[i].standings;
// Do stuff with standings
for (var j=0, jLen=standings.length; j<jLen; j++) {
stats = standings[j];
// Do stuff with stats
for (var k=0, kLen=stats.length; k<kLen; k++) {
value = stats[k].value;
// Do stuff with value
}
}
}
Of course I have no idea what the data is for, what the overall structure is or how you want to present it. But if you have deeply nested data, all you can do is dig into it. You might be able to write a recursive function, but it might also become very difficult to maintain if the data structure is complex.