feathers-datascript

A datascript and datomic service for FeathersJS.

See clj-crud for more inspiration.

Article on CRUD here and here

WIP: Under development

To help with development, you can run the tests with npm run test.

Create DB

import {datascript as d} from 'datascript'

var db = d.db_with(d.empty_db(schema), [data])

                     [

UPSERT (Insert/Update in one)

When a transaction is processed, all the temporary ids are translated to actual entity ids. Temporary ids with the same partition and negative number value are mapped to the same entity id. Temporary ids are mapped to new entity ids unless you use a temporary id with an attribute defined as :db/unique :db.unique/identity, in which case the system will map your temporary id to an existing entity if one exists with the same attribute and value (update) or will make a new entity if one does not exist (insert). All further adds in the transaction that apply to that same temporary id are applied to the "upserted" entity.

Please see Datomic Tutorial Section Adding, updating, and retracting data

ADD entity (generated ID)

To add nested object, use attribute refs, ie. :todo/project below

from: add-todo

let project = {':db/add': -1, ':project/name': 'my project'}

let todo = {':db/id': -2,
            ':todo/text:': 'clean kitchen',
            ':todo/done': false,
            ':todo/project': -1,
            ':todo/due': new Date(),
            ':todo/tags': ['house', 'chore']}

d.transact(conn, [project, todo]);

DELETE entity (by ID)

d.transact(conn, {':db/retractEntity': -1});

UPDATE entity (by ID)

See Add, since attributes/entities (same) are simply updated if already exists.

FIND by criteria

Datascript and Datomic both use datalog for queries.

In the example below, ?e is the entity ID and ?n and ?a are attribute values that must match

var q = '[:find ?n ?a 
          :where [?e "name" ?n] 
                 [?e "age" ?a]
        ]';

You can pass query parameters via :in

// pass parameter ?e using `in:`
q = '[:find ?aka 
      :in $ ?e 
      :where [?e "aka" ?aka]]'

assert_eq_set([["Ivan", 17]], d.q(q, db));

// passing multiple criteria arguments for `:in` - `?e` and `?email`
res     = d.q('[:find ?e ?email \
                  :in  $ [[?n ?email]] \
                  :where [?e "name" ?n]]',
                people_db,

Good luck and enjoy!