Re-design the "Relation" class

src/factory.ts

@@ -61,6 +61,7 @@ function createModelApi<
       const entity = createModel<Dictionary, ModelName>(
         modelName,
         definition,
+        dictionary,
         parsedModel,
         initialValues,
         db,
@@ -163,7 +164,7 @@ function createModelApi<
         return null
       }
 
-      const nextRecord = updateEntity(prevRecord, query.data, definition, db)
+      const nextRecord = updateEntity(prevRecord, query.data, definition)
 
       if (
         nextRecord[prevRecord[InternalEntityProperty.primaryKey]] !==
@@ -211,7 +212,7 @@ function createModelApi<
       }
 
       records.forEach((prevRecord) => {
-        const nextRecord = updateEntity(prevRecord, query.data, definition, db)
+        const nextRecord = updateEntity(prevRecord, query.data, definition)
 
         if (
           nextRecord[prevRecord[InternalEntityProperty.primaryKey]] !==

src/glossary.ts

@@ -6,7 +6,7 @@ import {
   QuerySelector,
   WeakQuerySelector,
 } from './query/queryTypes'
-import { RelationKind, ManyOf, OneOf } from './relations/Relation'
+import { OneOf, ManyOf } from './relations/Relation'
 
 export type KeyType = string | number | symbol
 export type AnyObject = Record<KeyType, any>
@@ -15,19 +15,6 @@ export type PrimitiveValueType = string | number | boolean | Date
 export type ModelValueType = PrimitiveValueType | PrimitiveValueType[]
 export type ModelValueTypeGetter = () => ModelValueType
 
-/**
- * Definition of the relation.
- * @example factory({ user: { post: oneOf('post') } })
- */
-export interface RelationDefinition<
-  Kind extends RelationKind,
-  ModelName extends KeyType,
-> {
-  kind: Kind
-  unique: boolean
-  modelName: ModelName
-}
-
 /**
  * Minimal representation of an entity to look it up
  * in the database and resolve upon reference.
@@ -46,7 +33,7 @@ export type ModelDefinitionValue =
   | ManyOf<any>
   | NestedModelDefinition
 
-type NestedModelDefinition = {
+export type NestedModelDefinition = {
   [propertyName: string]:
     | ModelValueTypeGetter
     | OneOf<any>
@@ -216,10 +203,10 @@ export type Value<
   [Key in keyof Target]: Target[Key] extends PrimaryKey<any>
     ? ReturnType<Target[Key]['getValue']>
     : // Extract value type from relations.
-    Target[Key] extends OneOf<any>
-    ? Entity<Dictionary, Target[Key]['modelName']>
-    : Target[Key] extends ManyOf<any>
-    ? Entity<Dictionary, Target[Key]['modelName']>[]
+    Target[Key] extends OneOf<infer ModelName>
+    ? Entity<Dictionary, ModelName>
+    : Target[Key] extends ManyOf<infer ModelName>
+    ? Entity<Dictionary, ModelName>[]
     : // Account for primitive value getters because
     // native constructors (i.e. StringConstructor) satisfy
     // the "AnyObject" predicate below.

src/model/createModel.ts

@@ -24,6 +24,7 @@ export function createModel<
 >(
   modelName: ModelName,
   definition: ModelDefinition,
+  dictionary: Dictionary,
   parsedModel: ParsedModelDefinition,
   initialValues: Partial<Value<Dictionary[ModelName], Dictionary>>,
   db: Database<Dictionary>,
@@ -92,9 +93,9 @@ export function createModel<
   )
 
   const entity = Object.assign({}, publicProperties, internalProperties)
-  defineRelationalProperties(entity, initialValues, relations, db)
+  defineRelationalProperties(entity, initialValues, relations, dictionary, db)
 
-  log('created "%s" entity', modelName, entity)
+  log('created "%s" entity:', modelName, entity)
 
   return entity
 }

src/model/defineRelationalProperties.ts

@@ -1,31 +1,16 @@
 import { debug } from 'debug'
 import get from 'lodash/get'
-import set from 'lodash/set'
-import { invariant } from 'outvariant'
 import { Database } from '../db/Database'
-import {
-  Entity,
-  InternalEntity,
-  InternalEntityProperty,
-  ModelDictionary,
-  Value,
-} from '../glossary'
-import { executeQuery } from '../query/executeQuery'
-import { first } from '../utils/first'
-import { definePropertyAtPath } from '../utils/definePropertyAtPath'
-import {
-  ProducedRelationsMap,
-  ProducedRelation,
-  RelationKind,
-} from '../relations/Relation'
-import { QuerySelectorWhere } from '../query/queryTypes'
+import { InternalEntity, ModelDictionary, Value } from '../glossary'
+import { RelationsMap } from '../relations/Relation'
 
 const log = debug('defineRelationalProperties')
 
 export function defineRelationalProperties(
   entity: InternalEntity<any, any>,
   initialValues: Partial<Value<any, ModelDictionary>>,
-  relations: ProducedRelationsMap,
+  relations: RelationsMap,
+  dictionary: ModelDictionary,
   db: Database<any>,
 ): void {
   log('defining relational properties...', { entity, initialValues, relations })
@@ -41,125 +26,10 @@ export function defineRelationalProperties(
       continue
     }
 
-    // Take the relational entity reference from the initial values.
-    const entityRefs: Entity<any, any>[] = [].concat(
-      get(initialValues, propertyPath),
-    )
-
-    log('entity references:', entityRefs)
-
-    if (relation.unique) {
-      log('"%s" is a unique relation, verifying..."', propertyPath)
-
-      // Trying to look up an entity of the same type
-      // that references the same relational entity.
-      const existingEntities = executeQuery(
-        entity[InternalEntityProperty.type],
-        entity[InternalEntityProperty.primaryKey],
-        {
-          where: set<QuerySelectorWhere<any>>({}, propertyPath, {
-            [relation.primaryKey]: {
-              in: entityRefs.map((entityRef) => {
-                return entityRef[relation.primaryKey]
-              }),
-            },
-          }),
-        },
-        db,
-      )
-
-      log(
-        `existing entities that reference the same "${propertyPath}"`,
-        existingEntities,
-      )
-
-      invariant(
-        existingEntities.length === 0,
-        'Failed to create a unique "%s" relation for "%s" (%s): the provided entity is already used.',
-        relation.modelName,
-        `${entity.__type}.${propertyPath}`,
-        entity[entity[InternalEntityProperty.primaryKey]],
-      )
-    }
-
-    addRelation(entity, propertyPath, relation, entityRefs, db)
-
-    log('relation "%s" successfuly set!', propertyPath)
-  }
-}
-
-export function addRelation(
-  entity: Entity<any, any>,
-  propertyPath: string,
-  relation: ProducedRelation,
-  references: Value<any, any> | Value<any, any>[],
-  db: Database<any>,
-): void {
-  const entityType = entity[InternalEntityProperty.type]
-  const referencesList = ([] as Value<any, any>[]).concat(references)
-  const referencedModels = db.getModel(relation.modelName)
-
-  log(
-    'adding a "%s" relational property "%s" on "%s" (%j)',
-    relation.kind,
-    propertyPath,
-    entityType,
-    references,
-  )
-  log(
-    'database records for the referenced "%s" model:',
-    relation.modelName,
-    referencedModels,
-  )
-
-  // All referenced entities must exist.
-  // This also guards against providing compatible plain objects as next values,
-  // because they won't have the corresponding records in the database.
-  referencesList.forEach((reference) => {
-    const referenceId = reference[relation.primaryKey]
-    invariant(
-      referencedModels.has(referenceId),
-      'Failed to add relational property "%s" on "%s": referenced entity with the id "%s" does not exist.',
+    const references: Value<any, ModelDictionary> = get(
+      initialValues,
       propertyPath,
-      entityType,
-      referenceId,
     )
-  })
-
-  definePropertyAtPath(entity, propertyPath, {
-    enumerable: true,
-    // Mark the property as configurable so that it can be re-defined.
-    // Relational properties may be re-defined when updated during the
-    // entity update ("update"/"updateMany").
-    configurable: true,
-    get() {
-      log(`get "${propertyPath}"`, relation)
-
-      const queryResult = referencesList.reduce<InternalEntity<any, any>[]>(
-        (result, entityRef) => {
-          return result.concat(
-            executeQuery(
-              relation.modelName,
-              relation.primaryKey,
-              {
-                where: {
-                  [relation.primaryKey]: {
-                    equals: entityRef[relation.primaryKey],
-                  },
-                },
-              },
-              db,
-            ),
-          )
-        },
-        [],
-      )
-
-      log(`resolved "${relation.kind}" "${propertyPath}" to`, queryResult)
-
-      return relation.kind === RelationKind.OneOf
-        ? first(queryResult)
-        : queryResult
-    },
-  })
+    relation.apply(entity, propertyPath, references, dictionary, db)
+  }
 }

src/model/parseModelDefinition.ts

@@ -1,16 +1,21 @@
 import { debug } from 'debug'
 import { invariant } from 'outvariant'
-import { ModelDefinition, PrimaryKeyType, ModelDictionary } from '../glossary'
+import {
+  ModelDefinition,
+  PrimaryKeyType,
+  ModelDictionary,
+  NestedModelDefinition,
+} from '../glossary'
 import { PrimaryKey } from '../primaryKey'
 import { isObject } from '../utils/isObject'
-import { Relation, ProducedRelationsMap } from '../relations/Relation'
+import { Relation, RelationsMap } from '../relations/Relation'
 
 const log = debug('parseModelDefinition')
 
 export interface ParsedModelDefinition {
   primaryKey: PrimaryKeyType
   properties: string[]
-  relations: ProducedRelationsMap
+  relations: RelationsMap
 }
 
 /**
@@ -68,19 +73,16 @@ function deepParseModelDefinition<Dictionary extends ModelDictionary>(
     if (value instanceof Relation) {
       // Resolve a relation against the dictionary to collect
       // the primary key names of the referenced models.
-      result.relations[propertyPath] = value.produce(dictionary)
+      result.relations[propertyPath] = value
       continue
     }
 
     // Nested objects.
-    if (isObject(value)) {
+    if (isObject<NestedModelDefinition>(value)) {
       deepParseModelDefinition(
         dictionary,
         modelName,
-        /**
-         * @fixme Extend the "ModelDefinition" type to denote nested objects as values.
-         */
-        value as any,
+        value,
         propertyPath,
         result,
       )