Add a trait to help building dynamic filters

crates/storage-pg/src/filter.rs

@@ -0,0 +1,65 @@
+// Copyright 2024 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// A filter which can be applied to a query
+pub(crate) trait Filter {
+    /// Generate a condition for the filter
+    ///
+    /// # Parameters
+    ///
+    /// * `has_joins`: Whether the condition has relationship joined or not
+    fn generate_condition(&self, has_joins: bool) -> impl sea_query::IntoCondition;
+}
+
+pub(crate) trait StatementExt {
+    /// Apply the filter to the query
+    ///
+    /// The query must NOT have any relationship joined
+    fn apply_filter<F: Filter>(&mut self, filter: F) -> &mut Self;
+}
+
+pub(crate) trait StatementWithJoinsExt {
+    /// Apply the filter to the query
+    ///
+    /// The query MUST have any relationship joined
+    fn apply_filter_with_joins<F: Filter>(&mut self, filter: F) -> &mut Self;
+}
+
+impl StatementWithJoinsExt for sea_query::SelectStatement {
+    fn apply_filter_with_joins<F: Filter>(&mut self, filter: F) -> &mut Self {
+        let condition = filter.generate_condition(true);
+        self.cond_where(condition)
+    }
+}
+
+impl StatementExt for sea_query::SelectStatement {
+    fn apply_filter<F: Filter>(&mut self, filter: F) -> &mut Self {
+        let condition = filter.generate_condition(false);
+        self.cond_where(condition)
+    }
+}
+
+impl StatementExt for sea_query::UpdateStatement {
+    fn apply_filter<F: Filter>(&mut self, filter: F) -> &mut Self {
+        let condition = filter.generate_condition(false);
+        self.cond_where(condition)
+    }
+}
+
+impl StatementExt for sea_query::DeleteStatement {
+    fn apply_filter<F: Filter>(&mut self, filter: F) -> &mut Self {
+        let condition = filter.generate_condition(false);
+        self.cond_where(condition)
+    }
+}

crates/storage-pg/src/lib.rs

@@ -1,4 +1,4 @@
-// Copyright 2021-2023 The Matrix.org Foundation C.I.C.
+// Copyright 2021-2024 The Matrix.org Foundation C.I.C.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -177,6 +177,7 @@ pub mod upstream_oauth2;
 pub mod user;
 
 mod errors;
+pub(crate) mod filter;
 pub(crate) mod iden;
 pub(crate) mod pagination;
 pub(crate) mod repository;