I need to create a 'List' object from the following db tables. I've already done this in a rails/datamapper application, but now I have a need to get specific lists into and out of a db through YAML.
List
Categories
Items
Item choices
e.g. given a list identifier, pull the initial list, the categories for that list, the items for those categories, and the choices for those items into some object, then output as a yaml file.
My first step is output a specific list to yaml, this shouldn't be a unique situation and I'm sure others have solved it before. From reading I'm guessing I need a multilevel hash of some sort, but all I've been able to do so far is get list and category...i.e. this is a bit out of my range right now, and I'm only working from the command line.
I'm asking for two things really to assist in sharpening my skill set:
guidance on working with a multiple level, nested hash situation to properly serialize an object for yaml, given a series of associated db tables
if there is an easier way that someone has already solved.
The included to_json (doc) method already allows you to easily nest related records, and choose what you want to output :
List.all.to_json(:only => {}, :include => {
:categories => { :only => {}, :include => {
:items => { :only => :your_attribute_name }
}
})
The next step is to convert it to yaml :
ActiveSupport::JSON.decode(your_json).to_yaml
Hope this helps
Related
I am trying to build a custom sorting for the product listings in shopware 6.
I want to include a foreign table (entity is: leasingPlanEntity), get the min of one of the fields of that table (period_price) and then order the search result by that value.
I have already built a Subscriber, and try it like that, what seems to work.
public static function getSubscribedEvents(): array
{
return [
//ProductListingCollectFilterEvent::class => 'addFilter'
ProductListingCriteriaEvent::class => ['addCriteria', 5000]
];
}
public function addCriteria(ProductListingCriteriaEvent $event): void
{
$criteria = $event->getCriteria();
$criteria->addAssociation('leasingPlan');
$criteria->addAggregation(new MinAggregation('min_period_price', 'leasingPlan.periodPrice'));
// Sortierung hinzufügen.
$availableSortings = $event->getCriteria()->getExtension('sortings') ?? new ProductSortingCollection();
$myCustomSorting = new ProductSortingEntity();
$myCustomSorting->setId(Uuid::randomHex());
$myCustomSorting->setActive(true);
$myCustomSorting->setTranslated(['label' => 'My Custom Sorting at runtime']);
$myCustomSorting->setKey('my-custom-runtime-sort');
$myCustomSorting->setPriority(5);
$myCustomSorting->setFields([
[
'field' => 'leasingPlan.periodPrice',
'order' => 'asc',
'priority' => 1,
'naturalSorting' => 0,
],
]);
$availableSortings->add($myCustomSorting);
$event->getCriteria()->addExtension('sortings', $availableSortings);
}
Is this already the right way to get the min(periodPrice)? Or is it taking just a random value out of the leasingPlan table to define the sort-order?
I didn't find a way, to define the min_period_price aggregate value in the $myCustomSorting->setFields Methods.
Update 1
Some days later, I asked a less complex question in the shopware community on slack:
Is it possible to use the DAL to define a subquery for an association in the product-listing?
It should generate something like:
FROM
JOIN (
SELECT ... FROM ... WHERE ... GROUP BY ... ORDER BY ...
) AS ...
The answer there was:
Don't think so
Update 2
I also did an in-deep anlysis of the DAL-Query-Builder, and it really seems to be not possible, to perform a subquery with the current version.
Update 3 - Different approach
A different approach might be, to define custom fields in the main entity. Every time a change is made on the main entity, the values of this custom fields should be recalculated.
It is a lot of overhead work, to realize this. Especially when the fields you are adding, are dependend on other data like the availability of a product in the store, for example.
So check, if it is worth the extra work. Would be better, to have a solution for building subqueries.
Unfortunately it seems that in your case there is no easy way to achieve this, if I understand the issue correctly.
Consider the following: for each product you can have multiple leasingPlan entities, and I assume that for a given context (like a specific sales channel or listing) that still holds. This means that you would have to sort the leasingPlan entities by price, then take the one with the lowest price, and then sort the products by their lowest-price leasingPlan's price.
There seems to be no other way to achieve that, and unfortunately for you, sorting is applied at the end, even if it is sort of a subquery.
So, for example, if you have the following snippet
$criteria = $event->getCriteria();
$criteria->addAssociation('leasingPlan');
$criteria->getAssociation('leasingPlan')
->addSorting(new FieldSorting('price', FieldSorting::ASCENDING))
->setLimit(1)
;
The actual price-sorting would be applied AFTER the leasingPlan entities are fetched - essentially the results would be sorted, meaning that you would not get the cheapest leasing plan per product, instead getting the first one.
You can only do something like that with filters, but in this case there is nothing to filter by - I assume you don't have one leasingPlan per SalesChannel or per language, so that you could limit that list to just one entry that could be used for sorting
That is not to mention that this could not be included in a ProductSortingEntity, but you could always work around that by plugging into the appropriate events and modifying the criteria during runtime
I see two ways to resolve your issue
Making another table which would store the cheapest leasingPlan per product and just using that as your association
Storing the information about the cheapest leasingPlans in e.g. cache and using that for filtering (caution: a mistake here would probably break the sorting, for example if you end up with too few or too many leasingPlans per product)
public function applyCustomSorting(ProductListingCriteriaEvent $event): void
{
// One leasingPlan per one product
$cheapestLeasingPlans = $this->myCustomService->getCheapestLeasingPlanIds();
$criteria = $event->getCriteria();
$criteria->addAssociation('leasingPlan');
$criteria->getAssociation('leasingPlan')
->addSorting(new FieldSorting('price', FieldSorting::ASCENDING))
->addFilter(new EqualsAnyFilter('id', $cheapestLeasingPlans))
;
}
And then you could sort by
$criteria->addSorting(new FieldSorting('leasingPlan.periodPrice', FieldSorting::ASCENDING));
There should be no need to add the association manually and to add the aggregation to the criteria, that should happen automatically behind the scenes if your custom sorting is selected in the storefront.
For more information refer to the official docs.
I have Team and Players classes and want to return the data in one JSON string which contains Team info but at the same time it displays all the information about the players.
class Team < ActiveRecord::Base
has_many :players
end
class Players < ActiveRecord::Base
belongs_to :team
end
I know how to retrieve the information about team and players but not in the same query. Another problem is I don't how to merge the result JSONs in one JSON.
team = Team.last.to_json
player = team.players.to_json
How can I query the info about Team and Players in the same query. I tried:
#team = Team.includes(:players).where(players: {team_id: Team.last}).last.to_json
and it only returns me information about the team. I want a JSON like:
-id
-name
-players
-player
-player
In case it's impossible, how can I merge into one JSON all the information from the two queries.
You can write a "join" to incorporate the players in the team with the team information. At that point you'll have a structure that has the information needed to create the JSON. See "12 Joining Tables" from the Active Record documentation for more information.
Or, you can make two separate queries, then create a bit more complex JSON hash or array allowing you to output both sets of data into one larger serialized object. For instance:
require 'json'
team = {
'name' => 'bears'
}
players = {
'1' => 'fred',
'2' => 'joe'
}
puts ({
'team' => team,
'players' => players
}).to_json
Here's the output:
{"team":{"name":"bears"},"players":{"1":"fred","2":"joe"}}
Here's the data returned back to the Ruby object:
data = '{"team":{"name":"bears"},"players":{"1":"fred","2":"joe"}}'
JSON[data]
# => {"team"=>{"name"=>"bears"}, "players"=>{"1"=>"fred", "2"=>"joe"}}
Also, since you're using Sinatra, it's not necessary to use Active Record. Sequel is a very good ORM, and is my personal favorite when working with Sinatra. You might find it easier to work with.
Another option to manual serialization is to use ActiveModel::Serializer which allows you to define relationships between objects and gives you finer grained choices of what to include when you serialize, what to filter out and what related objects to preload. An alternative could also be Rabl which also has quite a nice API.
If you're just playing around with a small amount of JSON this might be overkill, but it's a nice practice to be more organized
I'm building a advanced search functionality and, thanks to the help of some ruby fellows on SO, I've been already able to combine AND and OR conditions programmatically on different fields of the same class.
I ended up writing something similar to the accepted answer mentioned above, which I report here:
query = criteria.each_with_object({}) do |(field, values), query|
field = field.in if(values.is_a?(Array))
query[field] = values
end
MyClass.where(query)
Now, what might happen is that someone wants to search on a certain field with multiple criteria, something like:
"all the users where names contains 'abc' but not contains 'def'"
How would you write the query above?
Please note that I already have the regexes to do what I want to (see below), my question is mainly on how to combine them together.
#contains
Regex.new('.*' + val + '.*')
#not contains
Regex.new('^((?!'+ val +').)*$')
Thanks for your time!
* UPDATE *
I was playing with the console and this is working:
MyClass.where(name: /.*abc.*/).and(name: /^((?!def).)*$/)
My question remains: how do I do that programmatically? I shouldn't end up with more than two conditions on the same field but it's something I can't be sure of.
You could use an :$and operator to combine the individual queries:
MyClass.where(:$and => [
{ name: /.*abc.*/ },
{ name: /^((?!def).)*$/ }
])
That would change the overall query builder to something like this:
components = criteria.map do |field, value|
field = field.in if(value.is_a?(Array))
{ field => value }
end
query = components.length > 1 ? { :$and => components } : components.first
You build a list of the individual components and then, at the end, either combine them with :$and or, if there aren't enough components for :$and, just unwrap the single component and call that your query.
Am trying to set a product category on different collections but only the last collection defined in docpad.coffee actually sets it when trying it like so
firstCollection: ->
#getCollection("html").findAllLive().on "add", (model) ->
model.setMeta({category: 'first'})
secondCollection: ->
#getCollection("html").findAllLive().on "add", (model) ->
model.setMeta({category: 'second'})
document.categorywill be 'second' for all documents of each collection.
How to set the same meta data individually per doc in a collection?
What problem are you trying to solve? Because your approach is not going to work. If you share what you're trying to do, we may be able to suggest an alternative approach.
Your current approach won't work because you are setting a metadata property named "category" that is a string. That metadata property lives on the documents in the collection and not on the collection itself.
Both collections are pointing at the same set of documents. Each individual document can only have a single value for that property. It can't be both 'first' and 'second'. The last one to set it wins, and in this case, the event that sets it to 'second' is happening last and so all of the documents have 'second' as the value for that metadata property.
Update: I found a better way to do this: model.setMetaDefaults({foo:'bar'})
For example, to create a blog collection with a default cssClass of post:
collections: {
blog: function() {
return this.getCollection("documents")
.findAllLive({relativeOutDirPath:'blog'}, [{filename:-1}])
.on("add", function (model) {
model.setMetaDefaults({'cssClass': 'post'})
});
}
},
This would go in your docpad.coffee file or, in my case, docpad.js.
See a working example with full context at https://github.com/nfriedly/nfriedly.com/blob/master/docpad.js#L72 (collection is called "techblog", starts around like 72).
how do you retrieve an array of IDs in Mongoid?
arr=["id1","id2"]
User.where(:id=>arr)
You can do this easily if you are retrieving another attribute
User.where(:nickname.in=>["kk","ll"])
But I am wondering how to do this in mongoid -> this should be a very simple and common operation
Remember that the ID is stored as :_id and not :id . There is an id helper method, but when you do queries, you should use :_id:
User.where(:_id.in => arr)
Often I find it useful to get a list of ids to do complex queries, so I do something like:
user_ids = User.only(:_id).where(:foo => :bar).distinct(:_id)
Post.where(:user_id.in => user_ids)
Or simply:
arr = ['id1', 'id2', 'id3']
User.find(arr)
The above method suggested by browsersenior doesn't seem to work anymore, at least for me. What I do is:
User.criteria.id(arr)
user_ids = User.only(:_id).where(:foo => :bar).map(&:_id)
Post.where(:user_id.in => user_ids)
The solution above works fine when amount of users is small. But it will require a lot of memory while there are thousands of users.
User.only(:_id).where(:foo => :bar).map(&:_id)
will create a list of User objects with nil in each field except id.
The solution (for mongoid 2.5):
User.collection.master.where(:foo => :bar).to_a.map {|o| o['_id']}