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/**
* Basic integration tests for the $let expression.
*/
(function() {
"use strict";
load("jstests/aggregation/extras/utils.js"); // For assertErrorCode.
let coll = db.agg_expr_let;
coll.drop();
assert.commandWorked(coll.insert({zero: 0, one: 1, two: 2, three: 3, nested: {four: 4}}));
function testExpr(expression, output) {
const res = coll.aggregate([{$project: {output: expression}}]).toArray();
assert.eq(res.length, 1, tojson(res));
assert.eq(res[0].output, output, tojson(res));
// Test in group:
const result = coll.aggregate({$group: {_id: 0, res: {$sum: expression}}}).toArray();
assert.eq(result, [{_id: 0, res: output}]);
}
// Basic tests.
testExpr('$two', 2);
testExpr('$$CURRENT.two', 2);
testExpr('$$ROOT.two', 2);
// Using sub expressions.
testExpr({$add: ['$two', '$$CURRENT.three']}, 5);
testExpr({$add: ['$$CURRENT.two', '$$ROOT.nested.four']}, 6);
// Verify that the variables defined in $let work.
testExpr({$let: {vars: {a: 10}, in : '$$a'}}, 10);
testExpr({$let: {vars: {a: '$zero'}, in : '$$a'}}, 0);
testExpr({$let: {vars: {a: {$add: ['$one', '$two']}, b: 10}, in : {$multiply: ['$$a', '$$b']}}},
30);
// Verify that the outer level variable works in inner level $let.
testExpr({
$let: {
vars: {var1: 1},
in : {$let: {vars: {var2: "$$var1"}, in : {$sum: ["$$var1", "$$var2"]}}}
}
},
2);
// Verify that the outer level variables get overwritten by inner level variables.
testExpr({
$let: {
vars: {var1: "$one"},
in : {$let: {vars: {var2: "$$var1", var1: 3}, in : {$sum: ["$$var2", "$$var1"]}}}
}
},
4);
// $let changing CURRENT
testExpr({$let: {vars: {CURRENT: '$$ROOT.nested'}, in : {$multiply: ['$four', '$$ROOT.two']}}},
8);
testExpr({
$let: {
vars: {CURRENT: '$$CURRENT.nested'}, // using original value of CURRENT
in : {$multiply: ['$four', '$$ROOT.two']}
}
},
8);
testExpr({
$let: {
vars: {CURRENT: '$nested'}, // same as last
in : {$multiply: ['$four', '$$ROOT.two']}
}
},
8);
testExpr({
$let: {
vars: {CURRENT: {$const: {ten: 10}}}, // "artificial" object
in : {$multiply: ['$ten', '$$ROOT.two']}
}
},
20);
testExpr({
$let: {
vars: {CURRENT: '$three'}, // sets current to the number 3 (not an object)
in : {$multiply: ['$$CURRENT', '$$ROOT.two']}
}
},
6);
// Swapping with $let (ensures there is no ordering dependency in vars).
testExpr({
$let: {
vars: {x: 6, y: 10},
in : {
$let: {
vars: {x: '$$y', y: '$$x'}, // now {x:10, y:6}
in : {$subtract: ['$$x', '$$y']}
}
}
}
}, // Not commutative!
4); // 10-6 not 6-10 or 6-6
// Unicode is allowed.
testExpr({$let: {vars: {'日本語': 10}, in : '$$日本語'}},
10); // Japanese for "Japanese language".
// Can use ROOT and CURRENT directly with no subfield (SERVER-5916).
coll.drop();
coll.insert({_id: 'obj'});
assert.eq(coll.aggregate({$project: {_id: 0, obj: '$$ROOT'}}).toArray(), [{obj: {_id: 'obj'}}]);
assert.eq(coll.aggregate({$project: {_id: 0, obj: '$$CURRENT'}}).toArray(),
[{obj: {_id: 'obj'}}]);
assert.eq(coll.aggregate({$group: {_id: 0, objs: {$push: '$$ROOT'}}}).toArray(),
[{_id: 0, objs: [{_id: 'obj'}]}]);
assert.eq(coll.aggregate({$group: {_id: 0, objs: {$push: '$$CURRENT'}}}).toArray(),
[{_id: 0, objs: [{_id: 'obj'}]}]);
// Check name validity checks.
assertErrorCode(coll, {$project: {a: {$let: {vars: {ROOT: 1}, in : '$$ROOT'}}}}, 16867);
assertErrorCode(coll, {$project: {a: {$let: {vars: {FOO: 1}, in : '$$FOO'}}}}, 16867);
assertErrorCode(coll, {$project: {a: {$let: {vars: {_underbar: 1}, in : '$$FOO'}}}}, 16867);
assertErrorCode(coll, {$project: {a: {$let: {vars: {'a.b': 1}, in : '$$FOO'}}}}, 16868);
assertErrorCode(coll, {$project: {a: {$let: {vars: {'a b': 1}, in : '$$FOO'}}}}, 16868);
assertErrorCode(coll, {$project: {a: '$$_underbar'}}, 16870);
assertErrorCode(coll, {$project: {a: '$$with spaces'}}, 16871);
// Verify that variables defined in '$let' cannot be used to initialize other variables.
assertErrorCode(
coll,
[{$project: {output: {$let: {vars: {var1: "$one", var2: "$$var1"}, in : "$$var1"}}}}],
17276);
}());
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