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refactor: Abstract preloading logic to it's own class
Because, we want to use the same preloading concepts on a single model as well
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,209 @@ | ||
| /* | ||
| * @adonisjs/lucid | ||
| * | ||
| * (c) Harminder Virk <virk@adonisjs.com> | ||
| * | ||
| * For the full copyright and license information, please view the LICENSE | ||
| * file that was distributed with this source code. | ||
| */ | ||
|
|
||
| import { Exception } from '@poppinss/utils' | ||
| import { | ||
| ModelContract, | ||
| PreloadCallback, | ||
| RelationContract, | ||
| ModelConstructorContract, | ||
| ManyToManyExecutableQueryBuilder, | ||
| } from '@ioc:Adonis/Lucid/Model' | ||
|
|
||
| import { QueryClientContract } from '@ioc:Adonis/Lucid/Database' | ||
|
|
||
| type PreloadNode = { | ||
| relation: RelationContract, | ||
| callback?: PreloadCallback, | ||
| children: { relationName: string, callback?: PreloadCallback }[], | ||
| } | ||
|
|
||
| /** | ||
| * Exposes the API to define and preload relationships in reference to | ||
| * a model | ||
| */ | ||
| export class Preloader { | ||
| /** | ||
| * Registered preloads | ||
| */ | ||
| private _preloads: { [key: string]: PreloadNode } = {} | ||
|
|
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| constructor (private _model: ModelConstructorContract) { | ||
| } | ||
|
|
||
| /** | ||
| * Returns the preload node for the a given relationship name | ||
| */ | ||
| private _getPreloadedRelation (name: string) { | ||
| const relation = this._preloads[name] | ||
| if (!relation) { | ||
| throw new Exception(`Cannot process unregistered relationship ${name}`, 500) | ||
| } | ||
|
|
||
| relation.relation.boot() | ||
| return relation | ||
| } | ||
|
|
||
| /** | ||
| * Execute the related query | ||
| */ | ||
| private async _executeQuery ( | ||
| query: ManyToManyExecutableQueryBuilder, | ||
| preload: PreloadNode, | ||
| ): Promise<ModelContract[]> { | ||
| /** | ||
| * Pass nested preloads | ||
| */ | ||
| preload.children.forEach(({ relationName, callback }) => query.preload(relationName, callback)) | ||
|
|
||
| /** | ||
| * Invoke callback when defined | ||
| */ | ||
| if (typeof (preload.callback) === 'function') { | ||
| /** | ||
| * Type casting to superior type. | ||
| */ | ||
| preload.callback(query as ManyToManyExecutableQueryBuilder) | ||
| } | ||
|
|
||
| /** | ||
| * Execute query | ||
| */ | ||
| return query.exec() | ||
| } | ||
|
|
||
| /** | ||
| * Parses the relation name for finding nested relations. The | ||
| * children `relationName` must be further parsed until | ||
| * the last segment | ||
| */ | ||
| public parseRelationName (relationName: string) { | ||
| const relations = relationName.split('.') | ||
| const primary = relations.shift()! | ||
| const relation = this._model.$getRelation(primary) | ||
|
|
||
| /** | ||
| * Undefined relationship | ||
| */ | ||
| if (!relation) { | ||
| throw new Exception( | ||
| `${primary} is not defined as a relationship on ${this._model.name} model`, | ||
| 500, | ||
| 'E_UNDEFINED_RELATIONSHIP', | ||
| ) | ||
| } | ||
|
|
||
| return { | ||
| primary, | ||
| relation, | ||
| children: relations.length ? { relationName: relations.join('') } : null, | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Define relationship to be preloaded | ||
| */ | ||
| public preload (relationName: string, userCallback?: PreloadCallback) { | ||
| const { primary, relation, children } = this.parseRelationName(relationName) | ||
|
|
||
| const payload = this._preloads[primary] || { relation, children: [] } | ||
| if (children) { | ||
| payload.children.push(Object.assign(children, { callback: userCallback })) | ||
| } else { | ||
| payload.callback = userCallback | ||
| } | ||
|
|
||
| this._preloads[primary] = payload | ||
| return this | ||
| } | ||
|
|
||
| /** | ||
| * Process a single relationship for a single parent model | ||
| */ | ||
| public async processForOne ( | ||
| name: string, | ||
| model: ModelContract, | ||
| client: QueryClientContract, | ||
| ): Promise<void> { | ||
| /** | ||
| * Get the relation | ||
| */ | ||
| const relation = this._getPreloadedRelation(name) | ||
|
|
||
| /** | ||
| * Pull query for a single parent model instance | ||
| */ | ||
| const query = relation.relation.getQuery(model, client) | ||
|
|
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| /** | ||
| * Execute the query | ||
| */ | ||
| const result = await this._executeQuery(query as ManyToManyExecutableQueryBuilder, relation) | ||
|
|
||
| /** | ||
| * Set only one when relationship is hasOne or belongsTo | ||
| */ | ||
| if (['hasOne', 'belongsTo'].includes(relation.relation.type)) { | ||
| relation.relation.setRelated(model, result[0]) | ||
| return | ||
| } | ||
|
|
||
| /** | ||
| * Set relationships on model | ||
| */ | ||
| relation.relation.setRelated(model, result) | ||
| } | ||
|
|
||
| /** | ||
| * Process a single relationship for a many parent models | ||
| */ | ||
| public async processForMany ( | ||
| name: string, | ||
| models: ModelContract[], | ||
| client: QueryClientContract, | ||
| ): Promise<void> { | ||
| /** | ||
| * Get the relation | ||
| */ | ||
| const relation = this._getPreloadedRelation(name) | ||
|
|
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| /** | ||
| * Pull query for a single parent model instance | ||
| */ | ||
| const query = relation.relation.getEagerQuery(models, client) | ||
|
|
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| /** | ||
| * Execute the query | ||
| */ | ||
| const result = await this._executeQuery(query as ManyToManyExecutableQueryBuilder, relation) | ||
|
|
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| /** | ||
| * Set relationships on model | ||
| */ | ||
| relation.relation.setRelatedMany(models, result) | ||
| } | ||
|
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| /** | ||
| * Process all preloaded for many parent models | ||
| */ | ||
| public async processAllForMany (models: ModelContract[], client: QueryClientContract): Promise<void> { | ||
| await Promise.all(Object.keys(this._preloads).map((name) => { | ||
| return this.processForMany(name, models, client) | ||
| })) | ||
| } | ||
|
|
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| /** | ||
| * Processes all relationships for one parent model | ||
| */ | ||
| public async processAllForOne (model: ModelContract, client: QueryClientContract): Promise<void> { | ||
| await Promise.all(Object.keys(this._preloads).map((name) => { | ||
| return this.processForOne(name, model, client) | ||
| })) | ||
| } | ||
| } |
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