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Fix MONGOID-5020 Condition lifting breaks with symbol operators on Ru…
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…by <= 2.6 (#4915)

* MONGOID-5020 test cases for operators with symbols

* MONGOID-5020 convert hashes to indifferent access prior to query manipulation

* MONGOID-5020 queries are now more uniform

* MONGOID-5020 combine with $eq when conditions are given in the same argument

* MONGOID-5020 test all matrix of string/symbol operator types

* fix straggler test

* document the situation

* document $eq lifting

Co-authored-by: Oleg Pudeyev <[email protected]>
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@p-mongo @p
p-mongo and p authored Nov 17, 2020
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156 changes: 154 additions & 2 deletions docs/tutorials/mongoid-upgrade.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -18,10 +18,123 @@ please consult GitHub releases for detailed release notes and JIRA for
the complete list of issues fixed in each release, including bug fixes.


Upgrading to Mongoid 7.3
========================

The following sections describe significant changes in Mongoid 7.3.

Field Operator Stringification
------------------------------

Minor change: the ``and`` logical operator now stringifies field operators
in its arguments. Mongoid 7.3 behavior:

.. code-block:: ruby

Band.and(year: {'$in': [2020]})
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{"$in"=>[2020]}}
# options: {}
# class: Band
# embedded: false>

Mongoid 7.2 behavior:

.. code-block:: ruby

Band.and(year: {'$in': [2020]})
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{:$in=>[2020]}}
# options: {}
# class: Band
# embedded: false>

Note that this stringification does not yet happen for all query construction
paths. For example, ``where`` does not stringify operators in both Mongoid 7.3
and Mongoid 7.2:

.. code-block:: ruby

Band.where(year: {'$in': [2020]})
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{:$in=>[2020]}}
# options: {}
# class: Band
# embedded: false>

It is expected that over time, all operators will stringify the keys in their
arguments.


Condition Combination Using ``$eq``
-----------------------------------

Minor change: when using the ``and`` method on ``Criteria`` objects and
providing multiple conditions on the same field in the same argument to
``and``, conditions may be combined using ``$eq`` instead of ``$and``.
Mongoid 7.3 behavior:

.. code-block:: ruby

Band.and(year: 2020, :year.gt => 1960)
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{"$eq"=>2020, "$gt"=>1960}}
# options: {}
# class: Band
# embedded: false>

Band.and(:year.gt => 1960, year: 2020)
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{"$gt"=>1960, "$eq"=>2020}}
# options: {}
# class: Band
# embedded: false>

Mongoid 7.2 behavior:

.. code-block:: ruby

Band.and(year: 2020, :year.gt => 1960)
# =>
# #<Mongoid::Criteria
# selector: {"year"=>2020, "$and"=>[{"year"=>{"$gt"=>1960}}]}
# options: {}
# class: Band
# embedded: false>

Band.and(:year.gt => 1960, year: 2020)
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{"$gt"=>1960}, "$and"=>[{"year"=>2020}]}
# options: {}
# class: Band
# embedded: false>

This combination is not yet performed for ``where`` and other query methods:

.. code-block:: ruby

Band.where(:year.gt => 1960, year: 2020)
# =>
# #<Mongoid::Criteria
# selector: {"year"=>{"$gt"=>1960}, "$and"=>[{"year"=>2020}]}
# options: {}
# class: Band
# embedded: false>

Tt is expected that in the future other query methods will also favor
using ``$eq`` over ``$and``.


Upgrading to Mongoid 7.2
========================

The following sections describe major changes in Mongoid 7.2.
The following sections describe significant changes in Mongoid 7.2.

Embedded Document Matching
--------------------------
Expand Down Expand Up @@ -416,7 +529,7 @@ of the legacy query cache, see :ref:`the query cache documentation <query-cache>
Upgrading to Mongoid 7.1
========================

The following sections describe major changes in Mongoid 7.1.
The following sections describe significant changes in Mongoid 7.1.

Condition Combination
---------------------
Expand Down Expand Up @@ -448,6 +561,45 @@ Corresponding Mongoid 7.0 behavior:
# class: Band
# embedded: false>

**Known issue:** When using Ruby 2.6 and lower, when adding multiple conditions
on the same field using the same operator, the operator must be given as a
string, not as a symbol. The following invocations fail:

.. code-block:: ruby

Band.and({year: {'$in': [2020]}}, {year: {'$in': [2020]}})
# Traceback (most recent call last):
# 2: from (irb):10
# 1: from (irb):10:in `rescue in irb_binding'
# NoMethodError (undefined method `start_with?' for :$in:Symbol)

Band.and(year: {'$in': [2020]}).and(year: {'$in': [2020]})
# Traceback (most recent call last):
# 2: from (irb):11
# 1: from (irb):11:in `rescue in irb_binding'
# NoMethodError (undefined method `start_with?' for :$in:Symbol)

Use string keys instead:

.. code-block:: ruby

# Band.and({year: {'$in' => [2020]}}, {year: {'$in' => [2020]}})
# => #<Mongoid::Criteria
# selector: {"year"=>{"$in"=>[2020]}, "$and"=>[{"year"=>{"$in"=>[2020]}}]}
# options: {}
# class: Band
# embedded: false>

Band.and(year: {'$in' => [2020]}).and(year: {'$in' => [2020]})
# => #<Mongoid::Criteria
# selector: {"year"=>{"$in"=>[2020]}, "$and"=>[{"year"=>{"$in"=>[2020]}}]}
# options: {}
# class: Band
# embedded: false>

This issue is rectified in Mongoid 7.3.


Logical Operations
------------------

Expand Down
11 changes: 8 additions & 3 deletions lib/mongoid/criteria/queryable/mergeable.rb
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Expand Up @@ -227,7 +227,8 @@ def __multi__(criteria, operator)
end

# Takes a criteria hash and expands Key objects into hashes containing
# MQL corresponding to said key objects.
# MQL corresponding to said key objects. Also converts the input to
# BSON::Document to permit indifferent access.
#
# Ruby does not permit multiple symbol operators. For example,
# {:foo.gt => 1, :foo.gt => 2} is collapsed to {:foo.gt => 2} by the
Expand All @@ -237,15 +238,19 @@ def __multi__(criteria, operator)
# Similarly, this method should never need to expand a literal value
# and an operator at the same time.
#
# This method effectively converts symbol keys to string keys in
# the input +expr+, such that the downstream code can assume that
# conditions always contain string keys.
#
# @param [ Hash ] expr Criteria including Key instances.
#
# @return [ Hash ] The expanded criteria.
# @return [ BSON::Document ] The expanded criteria.
private def _mongoid_expand_keys(expr)
unless expr.is_a?(Hash)
raise ArgumentError, 'Argument must be a Hash'
end

result = {}
result = BSON::Document.new
expr.each do |field, value|
field.__expr_part__(value.__expand_complex__).each do |k, v|
if result[k]
Expand Down
16 changes: 16 additions & 0 deletions spec/integration/matcher_operator_data/in.yml
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Expand Up @@ -192,3 +192,19 @@
end: 20
excl: false
error: true

- name: scalar field - symbol operator - matches
document:
count: 10
query:
count:
:$in: [10, 11]
matches: true

- name: scalar field - symbol operator - does not match
document:
count: 8
query:
count:
:$in: [10, 11]
matches: false
2 changes: 1 addition & 1 deletion spec/mongoid/criteria/queryable/mergeable_spec.rb
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Expand Up @@ -44,7 +44,7 @@

describe '#_mongoid_expand_keys' do
it 'expands simple keys' do
query.send(:_mongoid_expand_keys, {a: 1}).should == {a: 1}
query.send(:_mongoid_expand_keys, {a: 1}).should == {'a' => 1}
end

let(:gt) do
Expand Down
87 changes: 71 additions & 16 deletions spec/mongoid/criteria/queryable/selectable_logical_spec.rb
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Expand Up @@ -417,6 +417,40 @@
it_behaves_like 'returns a cloned query'
end

context 'when criteria use operators' do
shared_examples 'behave correctly' do
let(:selection) do
query.and(
{ field: {first_operator => [ 1, 2 ] }},
{ field: {second_operator => [ 3, 4 ] }},
)
end

it "combines via $and operator and stringifies all keys" do
expect(selection.selector).to eq({
"field" => {'$in' => [ 1, 2 ]},
"$and" => [
{ "field" => {'$in' => [ 3, 4 ] }}
]
})
end
end

[
['$in', '$in'],
[:$in, '$in'],
['$in', :$in],
[:$in, :$in],
].each do |first_operator, second_operator|
context "when first operator is #{first_operator.inspect} and second operator is #{second_operator.inspect}" do
let(:first_operator) { first_operator }
let(:second_operator) { second_operator }

include_examples 'behave correctly'
end
end
end

context 'when criteria are handled via Key' do
shared_examples_for 'adds the conditions to top level' do

Expand Down Expand Up @@ -467,12 +501,23 @@
it_behaves_like 'returns a cloned query'
end

shared_examples_for 'combines conditions with $eq' do

it "combines conditions with $eq" do
expect(selection.selector).to eq({
"field" => {'$eq' => 3, '$lt' => 5},
})
end

it_behaves_like 'returns a cloned query'
end

context 'criteria are provided in the same hash' do
let(:selection) do
query.send(tested_method, :field => 3, :field.lt => 5)
end

it_behaves_like 'combines conditions with $and'
it_behaves_like 'combines conditions with $eq'
end

context 'criteria are provided in separate hashes' do
Expand Down Expand Up @@ -505,12 +550,23 @@
it_behaves_like 'returns a cloned query'
end

shared_examples_for 'combines conditions with $eq' do

it "combines conditions with $eq" do
expect(selection.selector).to eq({
"field" => {'$gt' => 3, '$eq' => 5},
})
end

it_behaves_like 'returns a cloned query'
end

context 'criteria are provided in the same hash' do
let(:selection) do
query.send(tested_method, :field.gt => 3, :field => 5)
end

it_behaves_like 'combines conditions with $and'
it_behaves_like 'combines conditions with $eq'
end

context 'criteria are provided in separate hashes' do
Expand Down Expand Up @@ -1270,14 +1326,14 @@
it_behaves_like 'returns a cloned query'
end

shared_examples_for 'adds one condition' do
shared_examples_for 'combines conditions with $eq' do

it "adds one condition" do
it "combines conditions with $eq" do
expect(selection.selector).to eq({
'field' => 3,
'$and' => [
{'field' => {'$lt' => 5}},
],
'field' => {
'$eq' => 3,
'$lt' => 5,
},
})
end

Expand All @@ -1289,7 +1345,7 @@
query.send(tested_method, :field => 3, :field.lt => 5)
end

it_behaves_like 'adds one condition'
it_behaves_like 'combines conditions with $eq'
end

context 'criteria are provided in separate hashes' do
Expand Down Expand Up @@ -1324,13 +1380,12 @@
it_behaves_like 'returns a cloned query'
end

shared_examples_for 'adds one condition' do
shared_examples_for 'combines conditions with $eq' do

it "adds one condition" do
expect(selection.selector).to eq({
'field' => {'$gt' => 3},
'$and' => ['field' => 5],
})
it "combines conditions with $eq" do
expect(selection.selector).to eq(
'field' => {'$gt' => 3, '$eq' => 5},
)
end

it_behaves_like 'returns a cloned query'
Expand All @@ -1341,7 +1396,7 @@
query.send(tested_method, :field.gt => 3, :field => 5)
end

it_behaves_like 'adds one condition'
it_behaves_like 'combines conditions with $eq'
end

context 'criteria are provided in separate hashes' do
Expand Down

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