I’ve got a problem that I’m not entirely sure I understand. I’ve got the following Elasticsearch query, written in PHP, with fuzziness matching hardcoded; this results in about an expected 1,500 search results.

private function phraseQuery(array $matchFields): array {
        return [
            'bool' => [
                "minimum_should_match" => 1,
                "should" => [
                    $this->multiMatch($matchFields),
                    [
                        'match' => [
                            'Title' => [
                                'query' => $this->searchTerm,
                                'fuzziness' => 'AUTO:4,8'
                            ]
                        ]
                    ], [
                        'match' => [
                            'TransliteratedTitle' => [
                                'query' => $this->searchTerm,
                                'fuzziness' => 'AUTO:4,8'
                            ]
                        ]
                    ]
                ]
            ]
        ];
    }

When I replace the ‘match’ parts of my query to dynamically generate with a function I get 4 exact search results; Elasticsearch effectively seems to ignore the fuzziness queries. I have confirmed on PHP Playground that the queries are structurally exactly the same, but there appears to be a difference between the two queries. Does the PHP spread operator not work in this way?

private function fuss(array $matchFields): array {
        $fuzziness = [];
        foreach($matchFields as $field) {
            $query = ['query' => $this->searchTerm , 'fuzziness' => 'AUTO:4,8'];
            $match = [ $field => $query ];
            $fuzziness[] = [ 'match' => $match ];
        }
        return $fuzziness;
}

private function phraseQuery(array $matchFields): array {
        return [
            'bool' => [
                "minimum_should_match" => 1,
                "should" => [
                    $this->multiMatch($matchFields),
                    ...$this->fuss($matchFields),
                ]
            ]
        ];
    }

Any help is much appreciated!

FYI: I’m using Elastic Cloud and PHP v8

I have tested my code on PHP playground to make sure the queries to Elasticsearch are structured in the exact same way. I have run both forms of query and one returns 4 results and the other nearly 1,500.