Develop Reference

Meteor render data from embeded, nested collection

I've been trying to get data out of a nested collection without any luck, besides using the dot notation from the html nothing seems to work.
What I want basically is to soley fetch the data I need from a nested collection. I'm trying to build a file upload for images and audio files and then a simple way to use the files. I'm using the cfs:standard-packages and cfs:filesystem packages.
The code below shows a working example of what I don't want, eg fetching the whole file object and retrieving the data in the html. If I could use the dot notation in the mongo command somehow would be perfect. I also could settle for _each but I would prefer fetching just the data I need on each db call. As you can see I'm passing an id for the whole file object here. Uploads.find({_id:Session.get('getpic')}); BTW, the actual file is stored in a folder on my local server.
The collection:
{
"_id" : "DXFkudDGCdvLpPALP",
"original" : {
"name" : "drink.png",
"updatedAt" : ISODate("2015-04-30T07:14:56.000Z"),
"size" : 127944,
"type" : "image/png"
},
"uploadedAt" : ISODate("2015-07-11T21:53:32.526Z"),
"copies" : {
"uploads" : {
"name" : "drink.png",
"type" : "image/png",
"size" : 127944,
"key" : "uploads-DXFkudDGCdvLpPALP-drink.png",
"updatedAt" : ISODate("2015-07-11T21:53:32.000Z"),
"createdAt" : ISODate("2015-07-11T21:53:32.000Z")
}
}
}
HTML
<template name="renderImages">
{{#each showpic}}
<img width="300" height="300" src="/projectuploads/{{copies.uploads.key}}"/>
{{/each}}
Javascript:
Template.renderImages.helpers({
showpic: function() {
return Uploads.find({_id:Session.get('getpic')});
}
});

specify the returned fields in the find query like so
return Uploads.find({_id:Session.get('getpic')}, { fields: {'copies.uploads.key': 1} } );
but a word on that. here you query minimongo (on the client), which is in the browsercache so it's basically free. take care to publish only those fields to the client that you actually want there.

MongoDB/NodeJS query to get data from dictionary

Hi in mongo DB I have a table "games" like this:
{
"_id" : ObjectId("53c66f922e15c4e5ee2655af"),
"name" : "alien-kindergarden",
"title" : "Alien Kindergarden",
"description" : "Alien description",
"gameCategory_id" : "1",
"deviceOrientation_id" : "1",
"position" : "1"
}
and I have a few dictionaries (also simple collections in MongoDB) like "gameCategory" for example:
{
"_id" : 0,
"name" : "GAME_CATEGORY_NO_CATEGORY"
}
{
"_id" : 1,
"name" : "GAME_CATEGORY_POPULAR"
}
How to get data from collection "games" with fields from my dictionary like:
{
"_id" : ObjectId("53c66f922e15c4e5ee2655af"),
"name" : "alien-kindergarden",
"title" : "Alien Kindergarden",
"description" : "Alien description",
"gameCategory" : GAME_CATEGORY_NO_CATEGORY, <---------------
"deviceOrientation_id" : "1",
"position" : "1"
}
Thanks. I'm using Node server for it.

What you are essentially asking for is a "JOIN" as in SQL. Your first point of reading should be that MongoDB does not do joins. The general concept here is "embedding" where the related information is actually contained within the document.
A good reading of the Data Modelling section of the official documentation can cover various points such as this and alternate approaches. But in most cases the data you wish to reference should just be part of the original document:
{
"_id" : ObjectId("53c66f922e15c4e5ee2655af"),
"name" : "alien-kindergarden",
"title" : "Alien Kindergarden",
"description" : "Alien description",
"gameCategory" : "GAME_CATEGORY_POPULAR",
"deviceOrientation_id" : "1",
"position" : "1"
}
This is generally because the MongoDB concept of being "scalable" is that all operations only ever deal with one collection at a time and "JOINS" are not attempted.
There are options available under node.js such as Mongoose that allow you to .populate() items from another "related" collection. But the general problem here is that you cannot "query" on the "related" information. All this really implements is a "query behind the scenes" approach. So more than one query is actually executed. To find by "related" information the best approach is generally:
var catId = db.category.findOne({ "name": "GAME_CATEGORY_POPULAR" })._id;
db.category.find({ "gameCategory_id": catId })
As nothing will let you query the "game" collection by a value held in a foreign collection.
The idea of "embedding" and generally "duplicating" data might seem alien to those used to relational database concepts. But really your reason for applying a solution such as MongoDB should be that you realize certain "relational patterns" are not the "best fit" for your application.
If you have not looked at this in that way, then perhaps you should stick with the relational database approach and use those tools. At least until you "find" the actual shortcomings and realize why you need to "design" around that.
Unlearn what you have learned.

Access ShareJS metadata from DerbyJS

DerbyJS uses ShareJS for its data synchronization. ShareJS stores various metadata values, as you can see here:
{ "id" : "ABCDEFG12345", "_type" : "http://sharejs.org/types/JSONv0", "_v" : 3, "_m" : { "mtime" : 1403674645713, "ctime" : 1403674645618 }, "_id" : "ABCDEFG12345" }
The _type, _v and _m fields are automatically generated by ShareJS.
I know there is a similar question over at Is it possible to access m.mtime or m.ctime from share.js in derby.js? , but the only provided solution is that it is possible to use these fields for querying.
Is there any way to access these properties from the fetched object using Derby ?

No. These fields are striped in ShareJS db adapter level.
source

ui-data contracts: client side extended validation of json data

I am in a few situations where json I am getting from services and database calls, created by another group, are giving me invalid data combinations, and causing many unintended errors downstream.
Given in the small example below, if the "rowContent" field is equal to "1", it's corresponding "row" needs to be a populated javascript object. "rowContent1" and "row1", and "rowContent2" and "row2" are correct. "rowContent3" and "row3" is not.
I concede the structure of this json is not fantastic. Ok it's a little wacky. It's fairly close to what I am dealing with in production. I have little control over it.
Are there data driven ways to describe json data relationships like this, that validate, before I start trying to use non-existent data in "row3"?
Or, what would you recommend I do in this situation?
thanks much,
-Larry
{ "table" : [
{
"aRowContent" : {
"rowContent1" : "1",
"rowContent2" : "0",
"rowContent3" : "1",
},
"row1" : {
"myRowValue" : "red"
},
"row2" : null,
"row3" : null
}
]
}

Not with JSON Schema, certainly. JSON Schema validates the structure of JSON data without cross-referencing to other bits of data.
I think the issue might be the redundancy in your data structure- why do you need /table/0/aRowContent/rowContent1 when you can deduce the same information from a null-check of /table/0/row1?

Backbone relational lazy loading

I'm using Backbone with my RESTful JSON API in order to create an app that works with posts and their comments. I've been trying to get Backbone Relational to work, but run into problems with my Lazy loading.
I load up a list of posts, without the related comments. On click of an post in the list, I open up a view that fetches the full Post, comments included, and renders this.
I've got 2 Backbone.RelationModels, Posts and Comments. The post relation to the comment is setup as folows:`
relations: [{
type: Backbone.HasMany,
key: 'comments',
relatedModel: 'Comment',
includeInJSON: true, // don't include it in the exporting json
collectionType: 'Comments'
}]
Now the problem I'm facing is that the relationships are initialized as soon as I retrieve my list, that do not contain the comments yet. I load up the full data later, by fetching the model by it's URI. However, the relationships don't seem to reinitialise, calling Posts.get(1).get('comments') returns a Comments collection that is empty!
Does anyone know how I could best tackle this problem? The data is there, it just seems the collection of the comments doesn't gets updated.
Edit: I can make the Post model bind it's change:comments to itself, which updates the collection. However, I can't seem to find a solid way to get the original comments' JSON, since this.get('comments') returns the Comments collection.
Note: In my collection, I do parse the JSON to make it work with my API, with the following code:
parse: function(response) {
var response_array = [];
_.each(response, function(item) {
response_array.push(item);
});
return response_array;
}
This is because the JSON returned by my API returns an object with indexed keys (associative array) instead of a native JSON array.
{
"id" : "1",
"title" : "post title",
"comments" : {
"2" : {
"id" : "2",
"description": "this should solve it"
},
"6" : {
"id" : "6",
"description": "this should solve it"
}
}
}
Thanks a bunch! Please ask any questions, I'm sure I've been vague somewhere!

The Backbone Relational model doesn't parse collections other then arrays, the JSON from my question didn't work. I changed the backend to return the comments in a proper array
{
"id" : "1",
"title" : "post title",
"comments" : [
{
"id" : "2",
"description": "this should solve it"
},
{
"id" : "6",
"description": "this should solve it"
}]
}
}
The RelationalModel doesn't respect the parse function that Backbone provides to parse your JSON before it moves on. With the backend returning "proper" JSON, the lazy loading works without any extra code.

You can also use the initialize method on your comment model, to simulate the parse method and define attributes with custom values like this (CoffeeScript):
initialize: (obj) ->
#attributes = obj.customKey