From 8dca36433c67c862b1b41ce68695d05a00f75dcb Mon Sep 17 00:00:00 2001
From: Kerollmops <clement@meilisearch.com>
Date: Tue, 7 Sep 2021 10:37:57 +0200
Subject: [PATCH 1/3] Introduce the new SortRankingRuleMissing user error
 variant

---
 milli/src/error.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/milli/src/error.rs b/milli/src/error.rs
index 9bda74631..56028f742 100644
--- a/milli/src/error.rs
+++ b/milli/src/error.rs
@@ -59,6 +59,7 @@ pub enum UserError {
     InvalidFilter(pest::error::Error<ParserRule>),
     InvalidFilterAttribute(pest::error::Error<ParserRule>),
     InvalidSortableAttribute { field: String, valid_fields: HashSet<String> },
+    SortRankingRuleMissing,
     InvalidStoreFile,
     MaxDatabaseSizeReached,
     MissingDocumentId { document: Object },
@@ -236,6 +237,10 @@ only composed of alphanumeric characters (a-z A-Z 0-9), hyphens (-) and undersco
                     field, valid_names
                 )
             }
+            Self::SortRankingRuleMissing => f.write_str(
+                "The sort ranking rule must be specified in the \
+                    ranking rules settings to use the sort parameter at search time",
+            ),
             Self::MissingDocumentId { document } => {
                 let json = serde_json::to_string(document).unwrap();
                 write!(f, "document doesn't have an identifier {}", json)

From fd3daa442362d23d9db477665faa6437fdb77593 Mon Sep 17 00:00:00 2001
From: Kerollmops <clement@meilisearch.com>
Date: Tue, 7 Sep 2021 10:52:19 +0200
Subject: [PATCH 2/3] Throw a query time error when a sort param is used but
 sort ranking rule is missing

---
 milli/src/search/mod.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/milli/src/search/mod.rs b/milli/src/search/mod.rs
index 56002b2e3..207f46f8a 100644
--- a/milli/src/search/mod.rs
+++ b/milli/src/search/mod.rs
@@ -18,7 +18,7 @@ pub(crate) use self::facet::ParserRule;
 pub use self::facet::{FacetDistribution, FacetNumberIter, FilterCondition, Operator};
 pub use self::matching_words::MatchingWords;
 use self::query_tree::QueryTreeBuilder;
-use crate::criterion::AscDesc;
+use crate::criterion::{AscDesc, Criterion};
 use crate::error::UserError;
 use crate::search::criteria::r#final::{Final, FinalResult};
 use crate::{DocumentId, Index, Result};
@@ -159,6 +159,14 @@ impl<'a> Search<'a> {
             }
         }
 
+        // We check that the sort ranking rule exists and throw an
+        // error if we try to use it and that it doesn't.
+        let sort_ranking_rule_missing = !self.index.criteria(self.rtxn)?.contains(&Criterion::Sort);
+        let empty_sort_criteria = self.sort_criteria.as_ref().map_or(true, |s| s.is_empty());
+        if sort_ranking_rule_missing && !empty_sort_criteria {
+            return Err(UserError::SortRankingRuleMissing.into());
+        }
+
         let criteria_builder = criteria::CriteriaBuilder::new(self.rtxn, self.index)?;
         let criteria = criteria_builder.build(
             query_tree,

From 5989528833d1f70baf49a288f566a09555ff052c Mon Sep 17 00:00:00 2001
From: Kerollmops <clement@meilisearch.com>
Date: Tue, 7 Sep 2021 11:01:37 +0200
Subject: [PATCH 3/3] Add a test to make sure we throw the right error message

---
 milli/tests/search/mod.rs  |  1 +
 milli/tests/search/sort.rs | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 milli/tests/search/sort.rs

diff --git a/milli/tests/search/mod.rs b/milli/tests/search/mod.rs
index 0fbc0e1b6..c34434c4e 100644
--- a/milli/tests/search/mod.rs
+++ b/milli/tests/search/mod.rs
@@ -13,6 +13,7 @@ use slice_group_by::GroupBy;
 mod distinct;
 mod filters;
 mod query_criteria;
+mod sort;
 
 pub const TEST_QUERY: &'static str = "hello world america";
 
diff --git a/milli/tests/search/sort.rs b/milli/tests/search/sort.rs
new file mode 100644
index 000000000..fe87f0623
--- /dev/null
+++ b/milli/tests/search/sort.rs
@@ -0,0 +1,23 @@
+use big_s::S;
+use milli::Criterion::{Attribute, Exactness, Proximity, Typo, Words};
+use milli::{AscDesc, Error, Search, UserError};
+
+use crate::search::{self, EXTERNAL_DOCUMENTS_IDS};
+
+#[test]
+fn sort_ranking_rule_missing() {
+    let criteria = vec![Words, Typo, Proximity, Attribute, Exactness];
+    // sortables: `tag` and `asc_desc_rank`
+    let index = search::setup_search_index_with_criteria(&criteria);
+    let rtxn = index.read_txn().unwrap();
+
+    let mut search = Search::new(&rtxn, &index);
+    search.query(search::TEST_QUERY);
+    search.limit(EXTERNAL_DOCUMENTS_IDS.len());
+    search.authorize_typos(true);
+    search.optional_words(true);
+    search.sort_criteria(vec![AscDesc::Asc(S("tag"))]);
+
+    let result = search.execute();
+    assert!(matches!(result, Err(Error::UserError(UserError::SortRankingRuleMissing))));
+}