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// Tests the behaviour of the $merge stage with whenMatched=[pipeline] and whenNotMatched=fail.
//
// Cannot implicitly shard accessed collections because a collection can be implictly created and
// exists when none is expected.
// @tags: [assumes_no_implicit_collection_creation_after_drop]
(function() {
"use strict";
load("jstests/aggregation/extras/utils.js"); // For assertArrayEq.
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.isMongos.
const source = db[`${jsTest.name()}_source`];
source.drop();
const target = db[`${jsTest.name()}_target`];
target.drop();
const mergeStage = {
$merge: {into: target.getName(), whenMatched: [{$addFields: {x: 2}}], whenNotMatched: "fail"}
};
const pipeline = [mergeStage];
// Test $merge when some documents in the source collection don't have a matching document in
// the target collection.
(function testMergeFailsIfMatchingDocumentNotFound() {
// Single document without a match.
assert.commandWorked(source.insert([{_id: 1, a: 1}, {_id: 2, a: 2}, {_id: 3, a: 3}]));
assert.commandWorked(target.insert([{_id: 1, b: 1}, {_id: 3, b: 3}]));
let error = assert.throws(() => source.aggregate(pipeline));
assert.commandFailedWithCode(error, ErrorCodes.MergeStageNoMatchingDocument);
assertArrayEq(
{actual: target.find().toArray(), expected: [{_id: 1, b: 1, x: 2}, {_id: 3, b: 3, x: 2}]});
// Multiple documents without a match.
assert(target.drop());
assert.commandWorked(target.insert([{_id: 1, b: 1}]));
error = assert.throws(() => source.aggregate(pipeline));
assert.commandFailedWithCode(error, ErrorCodes.MergeStageNoMatchingDocument);
assertArrayEq({actual: target.find().toArray(), expected: [{_id: 1, b: 1, x: 2}]});
})();
// Test $merge when all documents in the source collection have a matching document in the
// target collection.
(function testMergeWhenAllDocumentsHaveMatch() {
// Source has a single element with a match in the target.
assert(source.drop());
assert(target.drop());
assert.commandWorked(source.insert({_id: 3, a: 3}));
assert.commandWorked(target.insert([{_id: 1, b: 1}, {_id: 3, b: 3}]));
assert.doesNotThrow(() => source.aggregate(pipeline));
assertArrayEq(
{actual: target.find().toArray(), expected: [{_id: 1, b: 1}, {_id: 3, b: 3, x: 2}]});
// Source has multiple documents with matches in the target.
assert(target.drop());
assert.commandWorked(source.insert([{_id: 1, a: 1}, {_id: 2, a: 2}]));
assert.commandWorked(target.insert([{_id: 1, b: 1}, {_id: 2, b: 2}, {_id: 3, b: 3}]));
assert.doesNotThrow(() => source.aggregate(pipeline));
assertArrayEq({
actual: target.find().toArray(),
expected: [{_id: 1, b: 1, x: 2}, {_id: 2, b: 2, x: 2}, {_id: 3, b: 3, x: 2}]
});
})();
// Test $merge when the source collection is empty. The target collection should not be
// modified.
(function testMergeWhenSourceIsEmpty() {
assert.commandWorked(source.deleteMany({}));
assert(target.drop());
assert.commandWorked(target.insert([{_id: 1, b: 1}, {_id: 2, b: 2}]));
assert.doesNotThrow(() => source.aggregate(pipeline));
assertArrayEq({actual: target.find().toArray(), expected: [{_id: 1, b: 1}, {_id: 2, b: 2}]});
})();
// Test that variables referencing the fields in the source document can be specified in the
// 'let' argument and referenced in the update pipeline.
(function testMergeWithLetVariables() {
assert(source.drop());
assert(target.drop());
assert.commandWorked(source.insert([{_id: 1, a: 1, b: 1}, {_id: 2, a: 2, b: 2}]));
assert.commandWorked(target.insert([{_id: 1, c: 1}, {_id: 2, c: 2}]));
assert.doesNotThrow(() => source.aggregate([{
$merge: {
into: target.getName(),
let : {x: "$a", y: "$b"},
whenMatched: [{$set: {z: {$add: ["$$x", "$$y"]}}}],
whenNotMatched: "fail"
}
}]));
assertArrayEq(
{actual: target.find().toArray(), expected: [{_id: 1, c: 1, z: 2}, {_id: 2, c: 2, z: 4}]});
})();
}());
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