Lazy load ModelRelation query modifiers

src/db/ModelRelation.ts

@@ -5,7 +5,8 @@ import ModelFactory from "./ModelFactory";
 export default abstract class ModelRelation<S extends Model, O extends Model, R extends O | O[] | null> {
     protected readonly model: S;
     protected readonly foreignFactory: ModelFactory<O>;
-    protected readonly query: ModelQuery<O>;
+    private readonly query: ModelQuery<O>;
+    protected readonly queryModifiers: QueryModifier<O>[] = [];
     protected readonly filters: ModelFilter<O>[] = [];
     protected cachedModels?: R;
 
@@ -18,7 +19,7 @@ export default abstract class ModelRelation<S extends Model, O extends Model, R
     public abstract clone(): ModelRelation<S, O, R>;
 
     public constraint(queryModifier: QueryModifier<O>): this {
-        queryModifier(this.query);
+        this.queryModifiers.push(queryModifier);
         return this;
     }
 
@@ -27,13 +28,19 @@ export default abstract class ModelRelation<S extends Model, O extends Model, R
         return this;
     }
 
+    protected getFinalQuery(): ModelQuery<O> {
+        for (const modifier of this.queryModifiers) modifier(this.query);
+        this.queryModifiers.splice(0, this.queryModifiers.length); // Empty modifier now that they were applied
+        return this.query;
+    }
+
     public abstract getModelID(): any;
 
     protected abstract async compute(query: ModelQuery<O>): Promise<R>;
 
     public async get(): Promise<R> {
         if (this.cachedModels === undefined) {
-            this.cachedModels = await this.compute(this.query);
+            this.cachedModels = await this.compute(this.getFinalQuery());
         }
         return this.cachedModels;
     }
@@ -65,7 +72,7 @@ export class OneModelRelation<S extends Model, O extends Model> extends ModelRel
     }
 
     protected async compute(query: ModelQuery<O>): Promise<O | null> {
-        this.query.where(this.dbProperties.foreignKey, this.getModelID());
+        this.getFinalQuery().where(this.dbProperties.foreignKey, this.getModelID());
         return await query.first();
     }
 
@@ -85,8 +92,9 @@ export class OneModelRelation<S extends Model, O extends Model> extends ModelRel
         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);
+        const query = this.getFinalQuery();
-        return await this.query.get();
+        query.where(this.dbProperties.foreignKey, ids, WhereTest.IN);
+        return await query.get();
     }
 
     public async populate(models: ModelQueryResult<O>): Promise<void> {
@@ -116,7 +124,7 @@ export class ManyModelRelation<S extends Model, O extends Model> extends ModelRe
     }
 
     protected async compute(query: ModelQuery<O>): Promise<O[]> {
-        this.query.where(this.dbProperties.foreignKey, this.getModelID());
+        this.getFinalQuery().where(this.dbProperties.foreignKey, this.getModelID());
         return await query.get();
     }
 
@@ -138,8 +146,9 @@ export class ManyModelRelation<S extends Model, O extends Model> extends ModelRe
         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);
+        const query = this.getFinalQuery();
-        return await this.query.get();
+        query.where(this.dbProperties.foreignKey, ids, WhereTest.IN);
+        return await query.get();
     }
 
     public async populate(models: ModelQueryResult<O>): Promise<void> {
@@ -154,9 +163,10 @@ export class ManyThroughModelRelation<S extends Model, O extends Model> extends
     constructor(model: S, foreignFactory: ModelFactory<O>, dbProperties: PivotRelationDatabaseProperties) {
         super(model, foreignFactory);
         this.dbProperties = dbProperties;
-        this.query
+        this.constraint(query => query
             .leftJoin(`${this.dbProperties.pivotTable} as pivot`)
-            .on(`pivot.${this.dbProperties.foreignPivotKey}`, `${this.foreignFactory.table}.${this.dbProperties.foreignKey}`);
+            .on(`pivot.${this.dbProperties.foreignPivotKey}`, `${this.foreignFactory.table}.${this.dbProperties.foreignKey}`)
+        );
     }
 
     public clone(): ManyThroughModelRelation<S, O> {
@@ -168,7 +178,7 @@ export class ManyThroughModelRelation<S extends Model, O extends Model> extends
     }
 
     protected async compute(query: ModelQuery<O>): Promise<O[]> {
-        this.query.where(`pivot.${this.dbProperties.localPivotKey}`, this.getModelID());
+        this.getFinalQuery().where(`pivot.${this.dbProperties.localPivotKey}`, this.getModelID());
         return await query.get();
     }
 
@@ -190,9 +200,10 @@ export class ManyThroughModelRelation<S extends Model, O extends Model> extends
         const ids = relations.map(r => r.getModelID());
         if (ids.length === 0) return [];
 
-        this.query.where(`pivot.${this.dbProperties.localPivotKey}`, ids, WhereTest.IN);
+        const query = this.getFinalQuery();
-        this.query.pivot(`pivot.${this.dbProperties.localPivotKey}`, `pivot.${this.dbProperties.foreignPivotKey}`);
+        query.where(`pivot.${this.dbProperties.localPivotKey}`, ids, WhereTest.IN);
-        return await this.query.get();
+        query.pivot(`pivot.${this.dbProperties.localPivotKey}`, `pivot.${this.dbProperties.foreignPivotKey}`);
+        return await query.get();
     }
 
     public async populate(models: ModelQueryResult<O>): Promise<void> {