@rjavlonn/custom-criteria

NestCriteria

Installation

npm install --save @rjavlonn/nest-criteria

Initialisation

Just use it, no dependency injection needed, no module registration. Ready to go!

Usage

Filtering

Let's start with the controller. To get the value of the query parameter passed in the url, use the decorator @Criteria()

By default the decorator will look for the criteria query param, but you can override this behavior by passing the targeted key in argument.

    @Get()
    public list(@Criteria('other') criteria): Promise<PaginatedResults<Person>> {
        return this.personService
          .list(criteria);
    }    

Then on the service layer, use the .seach() method to convert the received criteria into the proper query.`.

    public list(criteria: IQueryCriteria<Person>): Promise<Person[]> {
        return this.personRepository
            .find(criteria.search());
    }

Pagination

Again, let's start with the controller.

WARNING: 🚨 Using @Criteria() decorator will set a guard for paginated results to 50. 🚨

    @Get()
    public paginate(@Criteria() criteria): Promise<PaginatedResults<Person>> {
        return this.personService
          .paginate(criteria);
    }    

The returned type is a PaginatedResults<T> allowing you to ensure your service is returning a paginated collection.

Then on the service layer, use the IQueryCriteria<T> to manipulate, if necessary, the criteria provided during the HTTP request interpretation.

    public paginate(criteria: IQueryCriteria<Person>): Promise<PaginatedResults<Person>> {
        return this.personRepository
            .paginate(criteria);
    }

Last but not least, the repository layer. Here we used TypeORM but the goal of this helper is to be ORM agnostic

@EntityRepository(Person)
export default class PersonRepository extends Repository<Person> implements Datasource<Person>, PaginateBehavior<Person> {
    paginate(criteria: IQueryCriteria<Person>): Promise<PaginatedResults<Person>> {
        return PaginationHelper.paginate(this, criteria);
    }
}

The PaginationHelper.paginate(datasource, critera) will take on the first argument a DataSource<T> ensuring the component is able to process criteria, the second argument is actually the IQueryCriteria<T> to use.

Demonstration

Expected format for the query param is JSON and different property will be looked for :

{
    index: number; // The targeted page 
    limit: number; // The maximum count of results per query
    filter: FilterConditions<T>; // An Object filtering result containing specific properties
    sort: { [P in keyof T]?:  1 | -1 }; // An Object sorting result by specific properties
    include: string[]; // The list of associated models to join to each results.
}

Filtering

http://enpoint.local/people?criteria={"filter": {"name": "Einstein"}}

[
    {
        "id": 2,
        "age": 42,
        "created_date": "2019-07-15T06:34:32.548Z",
        "updated_date": "2019-07-15T06:34:32.548Z",
        "name": "Einstein"       
    }
]

Advanced querying

This library is compliant with TypeORM operators.
To have a full usage overview, check the tests cases.

Key	Operator
$in	In
$lt	LessThan
$lte	LessThanOrEqual
$gt	MoreThan
$gte	MoreThanOrEqual
$like	Like
$eq	Equal
$null	IsNull
$not	Not
$bt (TypeORM only)	Between
$ne	NotEqual
$nin	NotIn
$or (Mongoose only)	-
$and (Mongoose only)	-

http://enpoint.local/people?criteria={"filter": {"name": {$not: "Einstein"}}}

[
    {
        "id": 1,
        "age": 142,
        "created_date": "2019-07-15T06:34:32.548Z",
        "updated_date": "2019-07-15T06:34:32.548Z",
        "name": "Camus"       
    },
    {
        "id": 3,
        "age": 72,
        "created_date": "2019-07-15T06:34:32.548Z",
        "updated_date": "2019-07-15T06:34:32.548Z",
        "name": "De Monaco"       
    }
]

The between case

The between() operator is a special one since you need to pass exactly two arguments.

http://enpoint.local/people?criteria={"filter": {"age": {$bt: [50, 100]}}}

[
    {
        "id": 3,
        "age": 72,
        "created_date": "2019-07-15T06:34:32.548Z",
        "updated_date": "2019-07-15T06:34:32.548Z",
        "name": "De Monaco"       
    }
]

Pagination

When the route is paginated by default: http://enpoint.local/people

{
    "results": [
        {
            "id": 1,
            "age": 142,
            "created_date": "2019-07-15T06:34:32.548Z",
            "updated_date": "2019-07-15T06:34:32.548Z",
            "name": "Camus"       
        },
        {
            "id": 2,
            "age": 42,
            "created_date": "2019-07-15T06:34:32.548Z",
            "updated_date": "2019-07-15T06:34:32.548Z",
            "name": "Einstein"       
        },
        {
            "id": 3,
            "age": 72,
            "created_date": "2019-07-15T06:34:32.548Z",
            "updated_date": "2019-07-15T06:34:32.548Z",
            "name": "De Monaco"       
        }
    ],
    "total": 3,
    "index": 0,
    "limit": 10,
    "previous": false,
    "next": false
}

With a pagination explicitly defined: http://enpoint.local/events?criteria={"index": 1, "limit": 1}

{
    "results": [
        {
            "id": 2,
            "age": 42,
            "created_date": "2019-07-15T06:34:32.548Z",
            "updated_date": "2019-07-15T06:34:32.548Z",
            "name": "Einstein"       
        }
    ],
    "total": 3,
    "index": 1,
    "limit": 1,
    "previous": true,
    "next": true
}