An example will be the best to describe my question
got this 2 documents
{ a : [] }
{ a [{x:1,y:2},{x:3,y:4}]
so both docs have this a attr
one empty one not
how can i select only a's that their array is not empty?
lets say model name is Model
I tried
Model.not.with_size(a:0)
without success
any direction?
Try this
Model.where(:a.not => {'$size' => 0})
Related
I'm stuck with a classic greatest-n-per-group problem, where a cat can have many kittens, but I'm usually just interested in the youngest.
I already do know how to build a scope and a has_one relation for the Cat.
My question: Is there a way to...
list all cats' names together with their youngest kittens' names...
while at the same time ordering them by their respective youngest kitten's name...
...using just a single SELECT under the hood?
What I got so far:
class Cat < ApplicationRecord
has_many :kittens
has_one :youngest_kitten, -> { merge(Kitten.youngest) }, foreign_key: :cat_id, class_name: :Kitten
scope :with_youngest_kittens, lambda {
joins(:kittens)
.joins(Kitten.younger_kittens_sql("cats.id"))
.where(younger_kittens: { id: nil })
}
end
class Kitten
belongs_to :cat
scope :youngest, lambda {
joins(Kitten.younger_kittens_sql("kittens.cat_id"))
.where(younger_kittens: { id: nil })
}
def self.younger_kittens_sql(cat_field_name)
%{
LEFT OUTER JOIN kittens AS younger_kittens
ON younger_kittens.cat_id = #{cat_field_name}
AND younger_kittens.created_at > kittens.created_at
}
end
end
When I run Cat.with_latest_kittens.order('kittens.name').map(&:name) everything looks fine: I get all the cats' names with just a single SELECT.
But when I run Cat.with_latest_kittens.order('kittens.name').map {|cat| cat.youngest_kitten.name}, I get the right result too, but a superfluous additional SELECT per cat is executed. Which is just logical, because the with_youngest_kittens doesn't know it should populate youngest_kitten. Is there a way to tell it or am I going about this all wrong?
I think adding an includes to your :with_youngest_kittens scope will fix the problem. Try changing the scope to
scope :with_youngest_kittens, lambda {
includes(:youngest_kitten)
.joins(:kittens)
.joins(Kitten.younger_kittens_sql("cats.id"))
.where(younger_kittens: { id: nil })
}
This should prevent Rails from making a separate database query for every kitten.
I found a solution that produces no extra SELECT, however it is quite ugly, so I'll actually go for localarrow's solution as it's more readable!
I thought I'd still post it for the sake of completeness (If someone needs the few ms extra performance):
First I add custom tailored select fields for each kitten column to the Cat.with_youngest_kitten scope:
scope :with_youngest_kittens, lambda {
kitten_columns = Kitten
.column_names
.map { |column_name| "kittens.#{column_name} AS `youngest_kittens.#{column_name}`" }
.join(', ')
joins(:kittens)
.joins(Kitten.latest_outer_join_sql("cats.id"))
.where(later_kittens: { id: nil })
.select("cats.*, #{kitten_columns}")
}
Then I override the has_one youngest_kitten relation with a method, that retrieves those custom selects and calls super if no data has been retrieved:
def youngest_kitten
return super if self[:'youngest_kittens.id'].nil?
kitten_hash = Hash[Kitten.column_names.collect { |column_name| [column_name, self[:"youngest_kittens.#{column_name}"]] }]
kitten_hash[:cat] = self
Kitten.new(kitten_hash)
end
I have a table message_thread:
id
sender_id
recipient_id
I want to declare a relation in my User model that will fetch all message threads as follows:
SELECT *
FROM message_thread
WHERE sender_id = {user.id}
OR recipent_id = {user.id}
I have tried the following:
public function getMessageThreads()
{
return $this->hasMany(MessageThread::className(), ['sender_id' => 'id'])
->orWhere(['recipient_id' => 'id']);
}
But it generates an AND query. Does anyone know how to do this?
You cannot create regular relation in this way - Yii will not be able to map related records for eager loading, so it not supporting this. You can find some explanation int this answer and related issue on GitHub.
Depending on use case you may try two approach to get something similar:
1. Two regular relations and getter to simplify access
public function getSenderThreads() {
return $this->hasMany(MessageThread::className(), ['sender_id' => 'id']);
}
public function getRecipientThreads() {
return $this->hasMany(MessageThread::className(), ['recipient_id' => 'id']);
}
public function getMessageThreads() {
return array_merge($this->senderThreads, $this->recipientThreads);
}
In this way you have two separate relations for sender and recipient threads, so you can use them directly with joins or eager loading. But you also have getter which will return result ofboth relations, so you can access all threads by $model->messageThreads.
2. Fake relation
public function getMessageThreads()
{
$query = MessageThread::find()
->andWhere([
'or',
['sender_id' => $this->id],
['recipient_id' => $this->id],
]);
$query->multiple = true;
return $query;
}
This is not real relation. You will not be able to use it with eager loading or for joins, but it will fetch all user threads in one query and you still will be able to use it as regular active record relation - $model->getMessageThreads() will return ActiveQuery and $model->messageThreads array of models.
Why orOnCondition() will not work
orOnCondition() and andOnCondition() are for additional ON conditions which will always be appended to base relation condition using AND. So if you have relation defined like this:
$this->hasMany(MessageThread::className(), ['sender_id' => 'id'])
->orOnCondition(['recipient_id' => new Expression('id')])
->orOnCondition(['shared' => 1]);
It will generate condition like this:
sender_id = id AND (recipent_id = id OR shared = 1)
As you can see conditions defined by orOnCondition() are separated from condition from relation defined in hasMany() and they're always joined using AND.
For this query
SELECT *
FROM message_thread
WHERE sender_id = {user.id}
OR recipent_id = {user.id}
You Can use these
$query = (new \yii\db\Query)->from("message_thread")
$query->orFilterWhere(['sender_id'=>$user_id])->orFilterWhere(['recipent_id '=>$user_id]);
I am trying to cleanup and optimize my come I am running on podio's API. What I am currently doing is using the filter query to return a collection from one app. I then loop over that collection. On each item I use Podio get_field_value to return the value(s) of a field in a referenced app. This creates a lot of API calls. I would like to retrieve everything in one API call Here is a simple version of my current code:
$collection = PodioItem::filter(WHSE_ID, array(
"filters" => array(
WHSE_EQUP_STATUS => array(2),
),
"sort_by" => WHSE_LOAD_IN,
"sort_desc" => false,
"limit" => 50
)
);
foreach ($collection as $item) {
// Table-A ID
$whId = $item->item_id;
// Referenced App Item(s)
$nucId = $item->fields[0]->values[0]->item_id;
// Get Referenced App Item Field
$app_b_value = PodioItem::get_field_value($nucId, NUC_LOAD_OUT);
echo $app_b_value;
}
Is there a more efficient way of doing this? I am thinking inline with the way you would use JOIN in a mysql query.
Thank you for any help you can provide!
if you are trying to get value from each item from filtered collection, you don't need to make podio calls each time.
Podio filter call will give you item with values. you just have to get value from each item.
like following
foreach ($podioFilterData['items'] as $itemData) {
$itemFields = $itemData['fields'];
foreach ($itemFields as $field) {
$value = $field['values'][0];
}
}
I'm trying to do a findAllByAttributes using a related model column as one of the criteria, but I keep getting a CDbException stating the column cannot be found.
Here's my model Relationship:
public function relations() {
return array(
'MetaData' => array(self::BELONGS_TO, 'ProjectMeta', 'wbse_or_io'),
);
}
And here's my attempted query:
$listing = ProjectIndex::model()->with('MetaData')
->findAllByAttributes(array(
'report_date'=>$reportDate,
'MetaData.cost_centre'=>$costCentre
)
);
From what I've read through Google/StackOverflow/these forums, I should be able to reference the cost_centre column in the MetaData relationship. But I keep getting the following error:
Table "tbl_project_index" does not have a column named "MetaData.cost_centre"
How do I reference the related table column?
Check this out
$listing = ProjectIndex::model()->with(
'MetaData'=>array(
'condition'=>'cost_centre = :cost_centre',
'params'=>array('cost_centre'=>$costCentre))
)
->findAllByAttributes(array('report_date'=>$reportDate));
The attributes in the attributes array cannot be for the related models. You can look at the source for findAllByAttributes for a better explanation. You can, however, pass the related attribute as a condition string or CDbCriteria array, in addition to Alex's answer.
$listing = ProjectIndex::model()->with('MetaData')->findAllByAttributes(
array('report_date'=>$reportDate),
'cost_centre = :cost_centre',
array(':cost_centre'=> $costCentre)
);
Or
$listing = ProjectIndex::model()->with('MetaData')->findAllByAttributes(
array('report_date'=>$reportDate),
array(
'condition' =>'cost_centre = :cost_centre',
'params'=>array(':cost_centre'=> $costCentre)
),
);
Summary
I've got a table of items that go in pairs. I'd like to self-join it so I can retrieve both sides of the pair in a single query. It's valid SQL (I think), the SQLite engine actually does accept it, but I'm having trouble getting DBIx::Class to bite the bullet.
Minimal example
package Schema::Half;
use parent 'DBIx::Class';
__PACKAGE__->load_components('Core');
__PACKAGE__->table('half');
__PACKAGE__->add_columns(
whole_id => { data_type => 'INTEGER' },
half_id => { data_type => 'CHAR' },
data => { data_type => 'TEXT' },
);
__PACKAGE__->has_one(dual => 'Schema::Half', {
'foreign.whole_id' => 'self.whole_id',
'foreign.half_id' => 'self.half_id',
# previous line results in a '='
# I'd like a '<>'
});
package Schema;
use parent 'DBIx::Class::Schema';
__PACKAGE__->register_class( 'Half', 'Schema::Half' );
package main;
unlink 'join.db';
my $s = Schema->connect('dbi:SQLite:join.db');
$s->deploy;
my $h = $s->resultset('Half');
$h->populate([
[qw/whole_id half_id data /],
[qw/1 L Bonnie/],
[qw/1 R Clyde /],
[qw/2 L Tom /],
[qw/2 R Jerry /],
[qw/3 L Batman/],
[qw/3 R Robin /],
]);
$h->search({ 'me.whole_id' => 42 }, { join => 'dual' })->first;
The last line generates the following SQL:
SELECT me.whole_id, me.half_id, me.data
FROM half me
JOIN half dual ON ( dual.half_id = me.half_id AND dual.whole_id = me.whole_id )
WHERE ( me.whole_id = ? )
I'm trying to use DBIx::Class join syntax to get a <> operator between dual.half_id and me.half_id, but haven't managed to so far.
Things I've tried
The documentation hints towards SQL::Abstract-like syntax.
I tried writing the has_one relationship as such:
__PACKAGE__->has_one(dual => 'Schema::Half', {
'foreign.whole_id' => 'self.whole_id',
'foreign.half_id' => { '<>' => 'self.half_id' },
});
# Invalid rel cond val HASH(0x959cc28)
Straight SQL behind a stringref doesn't make it either:
__PACKAGE__->has_one(dual => 'Schema::Half', {
'foreign.whole_id' => 'self.whole_id',
'foreign.half_id' => \'<> self.half_id',
});
# Invalid rel cond val SCALAR(0x96c10b8)
Workarounds and why they're insufficient to me
I could get the correct SQL to be generated with a complex search() invocation, and no defined relationship. It's quite ugly, with (too) much hardcoded SQL. It has to imitated in a non-factorable way for each specific case where the relationship is traversed.
I could work around the problem by adding an other_half_id column and joining with = on that. It's obviously redundant data.
I even tried to evade said redundancy by adding it through a dedicated view (CREATE VIEW AS SELECT *, opposite_of(side) AS dual FROM half...) Instead of the database schema it's the code that got redundant and ugly, moreso than the search()-based workaround. In the end I wasn't brave enough to get it working.
Wished SQL
Here's the kind of SQL I'm looking for. Please note it's only an example: I really want it done through a relationship so I can use it as a Half ResultSet accessor too in addition to a search()'s join clause.
sqlite> SELECT *
FROM half l
JOIN half r ON l.whole_id=r.whole_id AND l.half_id<>r.half_id
WHERE l.half_id='L';
1|L|Bonnie|1|R|Clyde
2|L|Tom|2|R|Jerry
3|L|Batman|3|R|Robin
Side notes
I really am joining to self in my full expanded case too, but I'm pretty sure it's not the problem. I kept it this way for the reduced case here because it also helps keeping the code size small.
I'm persisting on the join/relationship path instead of a complex search() because I've got multiple uses for the association, and I didn't find any "one size fits all" search expression.
Late update
Answering my own question two years later, it used to be a missing functionality that has since then been implemented.
For those still interested by this, it's finally been implemented as of 0.08192 or earlier. (I'm on 0.08192 currently)
One correct syntax would be:
__PACKAGE__->has_one(dual => 'Schema::Half', sub {
my $args = shift;
my ($foreign,$self) = #$args{qw(foreign_alias self_alias)};
return {
"$foreign.whole_id" => { -ident => "$self.whole_id" },
"$foreign.half_id" => { '<>' => { -ident => "$self.half_id" } },
}
});
Trackback: DBIx::Class Extended Relationships on fREW Schmidt's blog where I got to first read about it.
I think that you could do it by creating a new type of relationship extending DBIx::Class::Relationship::Base but it doesn't seem incredibly well documented. Have you considered the possibility of just adding a convenience method on the resultset set for Half that does a ->search({}, { join => ... } and returns the resultset from that to you? It's not introspectable like a relationship but other than that it works pretty much as well. It uses DBIC's ability to chain queries to your advantage.
JB, notice that instead of:
SELECT *
FROM half l
JOIN half r ON l.whole_id=r.whole_id AND l.half_id<>r.half_id
WHERE l.half_id='L';
You can write the same query using:
SELECT *
FROM half l
JOIN half r ON l.whole_id=r.whole_id
WHERE l.half_id<>r.half_id AND l.half_id='L';
Which will return the same data and is definitely easier to express using DBIx::Class.
Of course, this doesn't answer the question "How do I make DBIx::Class join tables using other operators than =?", but the example you showed doesn't justify such need.
Have you tried:
__PACKAGE__->has_one(dual => 'Schema::Half', {
'foreign.whole_id' => 'self.whole_id',
'foreign.half_id' => {'<>' => 'self.half_id'},
});
I believe the matching criteria in the relationship definition is the same used for searches.
Here is how to do it:
...
field => 1, # =
otherfield => { '>' => 2 }, # >
...
'foreign.half_id' => \'<> self.half_id'