typeorm-relations
v1.3.4
Published
Tools for working with TypeORM relations.
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A toolkit for working with TypeORM relations objects.
Installation
npm i typeorm-relations
This library is written in TypeScript, so type definitions are included in the box.
You must also install typeorm v0.3.x as a peer dependency (you should have this already).
Introduction
Relations in TypeORM are used to describe related objects. When defining your schema you can declare properties on your entities as representing either one-to-one, many-to-one, one-to-many, or many-to-many relations to other entities.
When fetching an entity, you use the relations
option on Repository/EntityManager
findX()
methods to tell TypeORM which of the entity's related entities should also be fetched from the database at the
same time, by way of SQL JOIN
clauses.
TypeORM v0.3.0 introduced a new object format for the relations
option. In earlier versions it only accepted an array
of strings, but the new object format allows for better type safety. A FindOptionsRelations
object looks like this:
{
profile: true,
photos: true,
videos: {
videoAttributes: true,
},
}
It's easy enough to write out relations objects by hand. But what if you need to select relations conditionally, or generate your relations based on some other information? Then you may find you want an easy way to manipulate relations objects by adding or removing entries, or merging multiple relations objects together.
That's where typeorm-relations
comes in! It's a toolkit for working with relations objects.
Usage
Use the RelationMap
class to work with relations when you're performing a query.
A simple example:
import { RelationMap } from 'typeorm-relations';
const userRelationMap = new RelationMap<User>({
profile: true,
photos: true,
videos: {
videoComments: true,
},
});
if (needsVideoAttributes) {
userRelationMap.add({
videos: {
videoAttributes: true,
},
});
}
const users = await userRepository.find({
/*
* When needsVideoAttributes === true, this will be equivalent to:
*
* relations: {
* profile: true,
* photos: true,
* videos: {
* videoComments: true,
* videoAttributes: true,
* },
* }
*/
relations: userRelationMap.toFindOptionsRelations(),
});
RelationMap
RelationMap.constructor(initial?: FindOptionsRelations | RelationMap)
Instantiate with new RelationMap()
. Pass a relations object to the constructor to set the initial value.
new RelationMap<User>({ profile: true });
RelationMap.add(relationsToAdd: FindOptionsRelations | RelationMap | string | string[]): this
Mutates the RelationMap
instance by adding relations. It's smart about merging relation objects, so that a true
value for a relation property will not clobber an existing object value containing nested relations.
Accepts several kinds of input:
Add a relations object, or another
RelationMap
instance, to merge the values.Example:
const relationMapA = new RelationMap<User>({ profile: true, videos: true, }); const relationMapB = new RelationMap<User>({ photos: { photoAttributes: true, }, videos: true, }); relationMapA.add({ videos: { videoAttributes: true, }, }); relationMapA.add(relationMapB);
Results in
relationMapA
containing the value:{ profile: true, videos: { videoAttributes: true }, photos: { photoAttributes: true } }
Add a single relation property by key name. Note: this only works with properties that exist at the top level of the given entity.
const relationMap = new RelationMap<User>({ profile: true, videos: true, }); relationMap.add('photos');
Results in
relationMap
containing the value:{ profile: true, videos: true, photos: true }
Add a single relation property by key path, specified as an array of strings.
const relationMap = new RelationMap<User>({ profile: true, videos: true, }); relationMap.add(['photos', 'photoAttributes']);
Results in
relationMap
containing the value:{ profile: true, videos: true, photos: { photoAttributes: true } }
RelationMap.remove(relationsToRemove: FindOptionsRelations | RelationMap | string | string[]): this
Mutates the RelationMap
instance by subtracting relations. Removing a nested path will remove all relations below the
given level.
Accepts input in the form of a relations object, another RelationMap
instance, or a single relation given by key name
or key path array.
Example:
const relations = new RelationMap<User>({
profile: true,
photos: {
photoAttributes: true,
},
videos: {
videoAttributes: true,
},
});
relations.remove({
videos: {
videoAttributes: true,
},
});
Results in relations
containing the value:
{
profile: true,
photos: {
photoAttributes: true
},
videos: true,
}
RelationMap.toFindOptionsRelations(): FindOptionsRelations
Returns a plain object representation of the relations, suitable for use with any of TypeORM's repository methods that
accept find
options.
Example:
const products = await dataSource.getRepository(Product).find({
relations: relationMap.toFindOptionsRelations(),
where: { ... },
order: { ... }
})
If you are using a SelectQueryBuilder
, you can join the relations using setFindOptions()
like this:
queryBuilder.setFindOptions({ relations: relationMap.toFindOptionsRelations() });
RelationMap.has(path: string | string[]): boolean
Accepts a relation path as a string or an array of strings and returns a boolean indicating whether the relation at that
path is selected for retrieval in the RelationMap
. If a single string is given as the path, it should refer to a top
level key of the entity, whereas an array path may look into deeper levels of relations.
Example:
const relationMap = new RelationMap<User>({
photos: {
photoAttributes: true,
},
videos: true,
});
if (relationMap.has('photos') && relationMap.has('videos')) {
console.log('User.photos and User.videos will be selected!');
}
if (relationMap.has(['photos', 'photoAttributes'])) {
console.log('User.photos.photoAttributes will be selected!');
}
Utility functions
If you prefer a more functional style, you can use these utilities directly instead of using the RelationMap
class.
mergeRelations(relationsA: FindOptionsRelations, relationsB: FindOptionsRelations): FindOptionsRelations
Returns a new relations object containing the result of merging the two relations objects passed as arguments.
Example:
import { mergeRelations } from 'typeorm-relations';
mergeRelations<User>({ profile: true }, { photos: { photoAttributes: true } });
Returns the value:
{
profile: true,
photos: {
photoAttributes: true
}
}
subtractRelations(relations: FindOptionsRelations, relationsToSubtract: FindOptionsRelations): FindOptionsRelations
Returns a new relations object containing the result of subtracting the second relation object from the first.
Example:
import { subtractRelations } from 'typeorm-relations';
subtractRelations<User>(
{
profile: true,
photos: { photoAttributes: true },
},
{
photos: { photoAttributes: true },
},
);
Returns the value:
{
profile: true,
photos: true
}
addRelationByPath(relations: FindOptionsRelations, path: string[]): FindOptionsRelations
Returns a new relations object containing the result of adding a relation property by key path, specified as an array of strings.
Example:
import { addRelationByPath } from 'typeorm-relations';
addRelationByPath<User>({ profile: true }, ['photos', 'photoAttributes']);
Returns the value:
{
profile: true,
photos: {
photoAttributes: true
}
}
removeRelationByPath(relations: FindOptionsRelations, path: string[]): FindOptionsRelations
Returns a new relations object containing the result of removing a relation property by key path, specified as an array of strings.
Example:
import { removeRelationByPath } from 'typeorm-relations';
removeRelationByPath<User>({ profile: true, photos: { photoAttributes: true } }, ['photos', 'photoAttributes']);
Returns the value:
{
profile: true,
photos: true
}
License
MIT