From cc884f70963b9ecc402475d4d92ee4c7ae9ffad0 Mon Sep 17 00:00:00 2001
From: Alice Gaudon <alice@gaudon.pro>
Date: Wed, 29 Jul 2020 16:17:30 +0200
Subject: [PATCH] ModelRelation eagerloading: don't make an SQL query when
 there is nothing to fetch

---
 src/db/ModelRelation.ts | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/db/ModelRelation.ts b/src/db/ModelRelation.ts
index c45d850..0762e8f 100644
--- a/src/db/ModelRelation.ts
+++ b/src/db/ModelRelation.ts
@@ -82,11 +82,10 @@ export class OneModelRelation<S extends Model, O extends Model> extends ModelRel
     }
 
     public async eagerLoad(relations: ModelRelation<S, O, O | null>[]): Promise<ModelQueryResult<O>> {
-        this.query.where(
-            this.dbProperties.foreignKey,
-            relations.map(r => r.getModelID()).filter(id => id !== null && id !== undefined),
-            WhereTest.IN
-        );
+        const ids = relations.map(r => r.getModelID()).filter(id => id !== null && id !== undefined);
+        if (ids.length === 0) return [];
+
+        this.query.where(this.dbProperties.foreignKey, ids, WhereTest.IN);
         return await this.query.get();
     }
 
@@ -136,11 +135,10 @@ export class ManyModelRelation<S extends Model, O extends Model> extends ModelRe
     }
 
     public async eagerLoad(relations: ModelRelation<S, O, O[]>[]): Promise<ModelQueryResult<O>> {
-        this.query.where(
-            this.dbProperties.foreignKey,
-            relations.map(r => r.getModelID()).filter(id => id !== null && id !== undefined),
-            WhereTest.IN
-        );
+        const ids = relations.map(r => r.getModelID()).filter(id => id !== null && id !== undefined);
+        if (ids.length === 0) return [];
+
+        this.query.where(this.dbProperties.foreignKey, ids, WhereTest.IN);
         return await this.query.get();
     }
 
@@ -189,10 +187,10 @@ export class ManyThroughModelRelation<S extends Model, O extends Model> extends
     }
 
     public async eagerLoad(relations: ModelRelation<S, O, O[]>[]): Promise<ModelQueryResult<O>> {
-        this.query.where(
-            `pivot.${this.dbProperties.localPivotKey}`,
-            relations.map(r => r.getModelID()),
-            WhereTest.IN);
+        const ids = relations.map(r => r.getModelID());
+        if (ids.length === 0) return [];
+
+        this.query.where(`pivot.${this.dbProperties.localPivotKey}`, ids, WhereTest.IN);
         this.query.pivot(`pivot.${this.dbProperties.localPivotKey}`, `pivot.${this.dbProperties.foreignPivotKey}`);
         return await this.query.get();
     }