Flatten Nested JSON to CSV: Dot Notation, Arrays, and Deep Objects
Flatten deeply nested JSON into flat CSV rows. Understand dot-notation key expansion, array exploding, and when flattening loses information.
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Tags: data, json, csv
Flatten Nested JSON to CSV: Dot Notation, Arrays, and Deep Objects Flattening nested JSON to CSV is the step that breaks most converters. The naive approach — iterate keys, write values — falls apart the moment you hit an object as a value or an array mid-record. This post covers the algorithms you actually need: dot-notation for nested objects, row-expansion versus joining for arrays, and strategies for inconsistent depth across records. Algorithm 1: Recursive Dot-Notation Flattening The standard approach uses depth-first recursion, accumulating the key path as it descends: Test it: Edge case: keys that already contain dots If your data has keys like , dot-notation creates ambiguity — is a flattened path or a literal key? Use a less common separator like or when this is a risk: ---…
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