fix: prevent negative slice index in populate subdocPath calculation #15862
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When calculating subdocPath in populate operations, if schema.path.length + 1 is greater than or equal to options.path.length, the slice operation would result in a negative index, causing incorrect path calculations. This fix adds Math.max(0, ...) to ensure the slice index never goes negative, preventing the slice() method from counting from the end of the string. Fixes three occurrences on lines 242, 304, and 325 in lib/helpers/populate/getModelsMapForPopulate.js
AbdelrahmanHafez
requested changes
Dec 4, 2025
AbdelrahmanHafez
added
the
needs clarification
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Description
This PR fixes a bug where calculating
subdocPathin populate operations could result in negative slice indices, causing incorrect path calculations.Fixes #15861
Problem
In
lib/helpers/populate/getModelsMapForPopulate.js, lines 242, 304, and 325 use:If
schema.path.length + 1 >= options.path.length, the second argument becomes negative, causingslice()to count from the end instead of the beginning.Solution
Added
Math.max(0, ...)to ensure the slice index never goes negative:Changes
Math.max(0, ...)wrapperMath.max(0, ...)wrapperMath.max(0, ...)wrapperTesting
test/model.populate.test.js)npm run lint)Impact
This fix prevents incorrect subdocPath calculations in edge cases where the schema path is longer than or equal to the options path, ensuring populate operations work correctly in all scenarios.