From 9c0a1cd9fdbad815937d5835720c6b3fd20009fe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <clement@meilisearch.com>
Date: Wed, 4 Sep 2024 17:48:49 +0200
Subject: [PATCH] Introduce the FieldIdFacetExistsDocidsExtractor

---
 milli/src/update/new/extract/faceted/mod.rs | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/milli/src/update/new/extract/faceted/mod.rs b/milli/src/update/new/extract/faceted/mod.rs
index e3c89b0e4..c885fd610 100644
--- a/milli/src/update/new/extract/faceted/mod.rs
+++ b/milli/src/update/new/extract/faceted/mod.rs
@@ -210,9 +210,23 @@ impl FacetedExtractor for FieldIdFacetStringDocidsExtractor {
     }
 }
 
-// Extract fieldid facet isempty docids
 // Extract fieldid facet isnull docids
-// Extract fieldid facet exists docids
+
+pub struct FieldIdFacetExistsDocidsExtractor;
+impl FacetedExtractor for FieldIdFacetExistsDocidsExtractor {
+    fn attributes_to_extract<'a>(rtxn: &'a RoTxn, index: &'a Index) -> Result<HashSet<String>> {
+        index.user_defined_faceted_fields(rtxn)
+    }
+
+    fn build_key<'b>(
+        field_id: FieldId,
+        _value: &Value,
+        output: &'b mut Vec<u8>,
+    ) -> Option<&'b [u8]> {
+        output.extend_from_slice(&field_id.to_be_bytes());
+        Some(&*output)
+    }
+}
 
 pub struct FieldIdFacetIsEmptyDocidsExtractor;
 impl FacetedExtractor for FieldIdFacetIsEmptyDocidsExtractor {