Start implementation of model relations

src/orm/model/relation/HasMany.ts

@@ -0,0 +1,47 @@
+import {Model} from '../Model'
+import {HasOneOrMany} from './HasOneOrMany'
+import {Collection} from '../../../util'
+import {RelationNotLoadedError} from './Relation'
+
+/**
+ * One-to-many relation implementation.
+ */
+export class HasMany<T extends Model<T>, T2 extends Model<T2>> extends HasOneOrMany<T, T2, Collection<T2>> {
+    protected cachedValue?: Collection<T2>
+
+    protected cachedLoaded = false
+
+    constructor(
+        parent: T,
+        related: T2,
+        foreignKeyOverride?: keyof T & string,
+        localKeyOverride?: keyof T2 & string,
+    ) {
+        super(parent, related, foreignKeyOverride, localKeyOverride)
+    }
+
+    /** Resolve the result of this relation. */
+    public get(): Promise<Collection<T2>> {
+        return this.fetch().collect()
+    }
+
+    /** Set the value of this relation. */
+    public setValue(related: Collection<T2>): void {
+        this.cachedValue = related.clone()
+        this.cachedLoaded = true
+    }
+
+    /** Get the value of this relation. */
+    public getValue(): Collection<T2> {
+        if ( !this.cachedValue ) {
+            throw new RelationNotLoadedError()
+        }
+
+        return this.cachedValue
+    }
+
+    /** Returns true if the relation has been loaded. */
+    public isLoaded(): boolean {
+        return this.cachedLoaded
+    }
+}