hychen/flutter_js_datascript

Using DataScript in Flutter Apps.

Using DataScript in Flutter Apps.

This package is in very early stage and only be tested on MacOS. Use it with caution and file any potential issues you see.

Features

Use this package to

• Transact with Datoms.
• Query result by using datalog language.

Supported APIs:

• creteConn
• q
• listen
• unlisten
• initDb
• datoms
• pull
• pullMany
• connFromDb
• connFromDatoms
• resetConn
• initDb
• dbWith
• emptyDb
• entityDb
• entity
• touch
• resolveTempids

Getting started

flutter pub add flutter_js_datascript

Usage

import 'package:flutter_js_datascript/flutter_js_datascript.dart';

void main() async {
    var d = Datascript();

    // create DB schema, a regular JS Object
    final builder = SchemaBuilder()
      ..attr('aka', cardinality: Cardinality.many)
      ..attr('friend', valueType: ValueType.ref);
    final schema = builder.build();

    // Use JS API to create connection and add data to DB
    // create connection using schema
    var conn = d.createConn(schema: schema);

    // setup listener called main
    // pushes each entity (report) to an Array of reports
    // This is just a simple example. Make your own!
    var reports = [];
    d.listen(conn, 'main', (report) {
      reports.add(report);
    });

    // define initial datoms to be used in transaction
    var datoms = [
      {
        ":db/id": -1,
        "name": "Ivan",
        "age": 18,
        "aka": ["X", "Y"]
      },
      {
        ":db/id": -2,
        "name": "Igor",
        "aka": ["Grigory", "Egor"]
      },
      // use :db/add to link datom -2 as friend of datom -1
      [":db/add", -1, "friend", -2]
    ];

    // Tx is Js Array of Object or Array
    // pass datoms as transaction data
    var report = d.transact(conn, datoms, txMeta: "initial info about Igor and Ivan");

    var db = d.db(conn);

    // Fetch names of people who are friends with someone 18 years old
    // query values from conn with JS API
    var result = await d.q(
        '[:find ?n :in \$ ?a :where [?e "friend" ?f] [?e "age" ?a] [?f "name" ?n]]',
        [db, 18]);
    // print query result to console!
    print(result);  // [["Igor"]]
}