I have an array of data that needs to be used to overwrite certain fields in a collection named "Players"
The structure of a Player looks like so:
The array of data that needs to go into documents in the Player collection is being passed into a controller function that looks like this:
exports.updateManyStats = (req, res) => {
console.log("updateManyStats API");
console.log(req.body.season);
console.log(req.body.stats);
Player.updateMany();
};
The console.logs looks like this:
What I need to do is overwrite the Players document fields goals , assists and pim for each person in the array (email is unique) where the season is whatever req.body.season is. In this case it is 2020-2021. The rest of the fields, like team, jersey, _id need to be left un-altered.
Question: What is the best way to do this? The only idea I have is to loop through each player and use $set, but that is not efficient. I feel like it might be possible with updateMany(), but not sure how to go about it that way.
Related
How I could append an element to an array like that ?.
Adding an item to an array structure like that, requires three steps:
Read the existing data.
Determine the key of the new item.
Write the new item.
In code that'd be something like:
const ref = admin.database().ref("javascript");
ref.once("value").then((snapshot) => {
let numChildren = parseInt(snapshot.numChildren());
ref.child(""+(numChildren+1)).set(4);
});
Note that this type of data structure is fairly non-idiomatic when it comes to Firebase, and I recommend reading:
Best Practices: Arrays in Firebase.
I am doing a Todo app with store.
All is good now , but i want to sort the items in the store , or maybe to show them ordered.
The store is an array , and all item in the store is an object with the keys : text,id,editing,line,checkboxed.
So "checkboxed" is a boolean value , and i want that all the "checkboxed:true" objects would be first in the array.
how could i do it ?
Or maybe :
how could i sort items in svelte-store-array in general ?
thanks !!!!
link to the app
You can create a derived store, like:
const sorted = derived(todos_, todos => sortBy(todos, 'checkboxed'))
Derives a store from one or more other stores. Whenever those
dependencies change, the callback runs.
(Example)
another solution :
to add that to the TodoLIst component :
$:sortedTodos=$customTodos
.sort((a,b)=>b.checkboxed-a.checkboxed)
.sort((a,b)=>a.line-b.line)
and work with sortedTodos variable in the "each" loop.
I seem to be stuck on a classic ORM issue and don't know really how to handle it, so at this point any help is welcome.
Is there a way to get the pivot table on a hasManyThrough query? Better yet, apply some filter or sort to it. A typical example
Table products
id,title
Table categories
id,title
table products_categories
productsId, categoriesId, orderBy, main
So, in the above scenario, say you want to get all categories of product X that are (main = true) or you want to sort the the product categories by orderBy.
What happens now is a first SELECT on products to get the product data, a second SELECT on products_categories to get the categoriesId and a final SELECT on categories to get the actual categories. Ideally, filters and sort should be applied to the 2nd SELECT like
SELECT `id`,`productsId`,`categoriesId`,`orderBy`,`main` FROM `products_categories` WHERE `productsId` IN (180) WHERE main = 1 ORDER BY `orderBy` DESC
Another typical example would be wanting to order the product images based on the order the user wants them to
so you would have a products_images table
id,image,productsID,orderBy
and you would want to
SELECT from products_images WHERE productsId In (180) ORDER BY orderBy ASC
Is that even possible?
EDIT : Here is the relationship needed for an intermediate table to get what I need based on my schema.
Products.hasMany(Images,
{
as: "Images",
"foreignKey": "productsId",
"through": ProductsImagesItems,
scope: function (inst, filter) {
return {active: 1};
}
});
Thing is the scope function is giving me access to the final result and not to the intermediate table.
I am not sure to fully understand your problem(s), but for sure you need to move away from the table concept and express your problem in terms of Models and Relations.
The way I see it, you have two models Product(properties: title) and Category (properties: main).
Then, you can have relations between the two, potentially
Product belongsTo Category
Category hasMany Product
This means a product will belong to a single category, while a category may contain many products. There are other relations available
Then, using the generated REST API, you can filter GET requests to get items in function of their properties (like main in your case), or use custom GET requests (automatically generated when you add relations) to get for instance all products belonging to a specific category.
Does this helps ?
Based on what you have here I'd probably recommend using the scope option when defining the relationship. The LoopBack docs show a very similar example of the "product - category" scenario:
Product.hasMany(Category, {
as: 'categories',
scope: function(instance, filter) {
return { type: instance.type };
}
});
In the example above, instance is a category that is being matched, and each product would have a new categories property that would contain the matching Category entities for that Product. Note that this does not follow your exact data scheme, so you may need to play around with it. Also, I think your API query would have to specify that you want the categories related data loaded (those are not included by default):
/api/Products/13?filter{"include":["categories"]}
I suggest you define a custom / remote method in Product.js that does the work for you.
Product.getCategories(_productId){
// if you are taking product title as param instead of _productId,
// you will first need to find product ID
// then execute a find query on products_categories with
// 1. where filter to get only main categoris and productId = _productId
// 2. include filter to include product and category objects
// 3. orderBy filter to sort items based on orderBy column
// now you will get an array of products_categories.
// Each item / object in the array will have nested objects of Product and Category.
}
I’ve just started to use Cloudant and I just can’t get my head around the map functions. I’ve been fiddling with the data below but it isn’t working out as I expected.
The relationship is, a user can have many vehicles. A vehicle belongs to 1 user. The vehicle ‘userId’ is the key of the user. There is a bit of redundancy as in user the _id and userId is the same, guess later is not required.
Anyhow, how can I find for a/every user, the vehicles which belong to it? The closest I’ve come through trial and error is a result which displays the owner of every vehicle, but I would like it the other way round, the user and the vehicles belonging to it. All the examples I’ve found use another document which ‘joins’ two or more documents, but I don’t need to do that?
Any point in the right direction appreciated - I really have no idea.
function (doc) {
if (doc.$doctype == "vehicle")
{
emit(doc.userId, {_id: doc.userId});
}
}
EDIT: Getting closer. I'm not sure exactly what I was expecting, but the result seems a bit 'messy'. Row[0] is the user document, row[n > 0] are the vehicle documents. I guess it's fine when a startkey/endkey is used, but without the results are a bit jumbled up.
function (doc) {
if (doc.$doctype == 'user') {
emit([doc._id, 0], doc);
} else if (doc.$doctype == 'vehicle') {
emit([doc.userId, 1, doc._id], doc);
}
}
A user is described as,
{
"_id": "user:10",
"firstname": “firstnamehere",
"secondname": “secondnamehere",
"userId": "user:10",
"$doctype": "user"
}
a vehicle is described as,
{
"_id": "vehicle:4002”,
“name”: “avehicle”,
"userId": "user:10",
"$doctype": "vehicle",
}
You're getting in the right direction! You already got that right with the global IDs. Having the type of the document as part of the ID in some form is a very good idea, so that you don't get confused later (all documents are in the same "pot").
Here are some minor problems with your current solution (before getting to your actual question):
Don't emit the doc as value in emit(key, value). You can always ask for the document that belongs to a view row by querying with include_docs=true. Having the doc as view value increases the view indexes a lot. When you don't need a specific value, use emit(key, null).
You also don't need the ID in the emit value. You'll get the ID of the document that belongs to a view row as part of the row anyway.
View Collation
Now to your problem of aggregating the vehicles with their user. You got the basic pattern right. This pattern is called view collation, you can read more about it in the CouchDB docs (ignore that it is in the "Couchapp" section).
The trick with view collation is that you return two or more types of documents, but make sure that they are sorted in a way that allows for direct grouping. Thus it is important to understand how CouchDB sorts the view result. See the collation specification for more information on that one. An important key to understanding view collation is that rows with array keys are sorted by key elements. So when two rows have the same key[0], they sort by key[1]. If that's equal as well, key[2] is considered, and so on.
Your map function frist groups users and vehicles by user ID (key[0]). Your map function then uses the fact that 0 sorts before 1 in the second element of the key, so your view will contain the following:
user 1
vehicle of user 1
vehicle of user 1
vehicle of user 1
user 2
user 3
vehicle of user 3
user 4
etc.
As you can see, the vehicles of a user immediately follow their user. Thus you can group this result into aggregates without performing expensive sort or lookup operations.
Note that users are sorted according to their ID, and vehicles within users also according to their ID. This is because you use the IDs in the key array.
Creating Queries
Now that view isn't worth much if you can't query according to your needs. A view as you have it supports the following queries:
Get all users with their vehicles
Get a range of users with their vehicles
Get a single user with its vehicles
Get a single user without vehicles (you could also use the _all_docs view for that though)
Example query for "all users between user 1 and user 3 (inclusive) with their vehicles"
We want to query for a range, so we use startkey and endkey in the query:
startkey=["user:1", 0]
endkey=["user:3", 1, {}]
Note the use of {} as sentinel value, which is required so that the end key is larger than any row that has a key of ["user:3", 1, (anyConceivableVehicleId)]
I've using Kohana for a couple of weeks. One thing I noticed is that Kohana is missing eager loading (as far as I know). Let's say I have the following tables.
Subjects
id
name
Chapters
id
subject_id
name
Videos
id
chapter_id
name
When a user opens a subject page, I want to display all the chapters and videos. With ORM, I can do
$tutorials = ORM::factory('subject')->where('id','=', 1)->find();
foreach($tutorials as $tutorial)
{
$chapters = $tutorial->chapters->find_all();
foreach($chapters as $chapter)
{
$videos = $chapter->videos->find_all();
}
}
The above code is not efficient since it makes too many queries.
I thought about using join or database query builder, but both of them do not return a model object as their results. I also looked into with(), but it seems like it only works with one-to-one relationship.
using join on an ORM object returns an OPM object, but it doesn't return the data from the joining tables.
What would be my best option here? I would like to minimize # of queries and also want to get ORM objects a result. Whatever it would be, should return all the columns from tutorials, chapters, and videos.
First of all, your code is excess. ORM method find() returns 1 Model_Subject object. See
$chapters = ORM::factory('subject', 1)->chapters->find_all();
foreach($chapters as $chapter)
{
$videos = $chapter->videos->find_all();
}
With DB builder you can make just 2 requests. First get array of all chapters ids:
$chapters = DB::select('id')
->from('chapters')
->where('subject_id', '=', '1')
->execute()
->as_array(NULL, 'id');
Second - get all videos by ids as Model_Video object
$videos = DB::select('id')
->from('videos')
->where('chapter_id', 'IN', $chapters)
->as_object('Model_Video')
->execute()
->as_array();
So I guess you want something like this.
$videos = ORM::factory('Video')
->join(array('chapters', 'chapter'), 'LEFT')->on('video.chapter_id', '=', 'chapter.id')
->join(array('subjects', 'subject'), 'LEFT')->on('chapter.subject_id', '=', 'subject.id')
->where('subject.id', '=', $id)
->find_all();
Come to think of it, if the video belongs_to chapter belongs_to subject, try the following using with():
$videos = ORM::factory('Video')
->with('chapter:subject') // These are the names of the relationships. `:` is separator
// equals $video->chapter->subject;
->where('subject.id', '=', $id)
->find_all();
With things like this it often helps to think 'backwards'. You need the videos on that subject so start with the videos instead of the subject. :)
EDIT: The drawback of the second function is that it is going to preload all the data, it might be shorter to write but heavier on the server. I'd use the first one unless I need to know the subject and chapter anyway.