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33 changes: 33 additions & 0 deletions .gitignore
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# Miscellaneous
*.class
*.log
*.pyc
*.swp
.DS_Store
.atom/
.buildlog/
.history
.svn/
migrate_working_dir/

# IntelliJ related
*.iml
*.ipr
*.iws
.idea/

# The .vscode folder contains launch configuration and tasks you configure in
# VS Code which you may wish to be included in version control, so this line
# is commented out by default.
#.vscode/

# Flutter/Dart/Pub related
# Libraries should not include pubspec.lock, per https://dart.dev/guides/libraries/private-files#pubspeclock.
/pubspec.lock
**/doc/api/
.dart_tool/
.packages
build/

# Test store
store/
10 changes: 10 additions & 0 deletions .metadata
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# This file tracks properties of this Flutter project.
# Used by Flutter tool to assess capabilities and perform upgrades etc.
#
# This file should be version controlled and should not be manually edited.

version:
revision: 75927305ff855f76a9ef704f9b4a86fa2fce7292
channel: beta

project_type: package
3 changes: 3 additions & 0 deletions CHANGELOG.md
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## 0.0.1

* TODO: Describe initial release.
201 changes: 201 additions & 0 deletions LICENSE
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Apache License
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Copyright [2022] [Daniel Cachapa]

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100 changes: 100 additions & 0 deletions README.md
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> ⚠ This package is still under development and may not be stable
Dart implementation of Conflict-free Replicated Data Types (CRDTs) using a Sqlite database for data storage.
This project is a continuation of the [crdt](https://github.com/cachapa/crdt) package and may depend on it in the future.

## Notes

`sqlite_crdt` has no intention of being an ORM - on the contrary, ideally it should look like using a normal SQL database. Unfortunately that's not possible at this time because CRDTs have a few properties that need to be guaranteed:

* Every change needs to be associated to `hlc` and `modified` timestamps
* There are different rules to generating the timestamps depending on whether data is being inserted or merged
* Timestamp generation require non-trivial checks, e.g. clock drift, duplicate nodes, etc.
* Records may not be deleted, but rather marked by setting the `is_deleted` flag

For those reasons, while the raw sqlite database is exposed, changes to the database should only be made using the provided methods `insert` `update` `merge` `setDeleted` and their siblings.

## Usage

```dart
// Create or load the database
final crdt = await SqliteCrdt.open(
'store',
'sqlite_crdt_test',
['users'],
version: 1,
onCreate: (db, version) {
// Use [createCrdtTable] to automatically add the CRDT columns
db.createCrdtTable('''
CREATE TABLE users (
id INTEGER NOT NULL,
name TEXT,
PRIMARY KEY (id)
)
''');
// You can also create non-crdt tables, they will be ignored
db.execute('''
CREATE TABLE not_a_crdt (
id TEXT NOT NULL,
count INTEGER,
PRIMARY KEY (id)
)
''');
},
);
// Insert data into the database
await crdt.insert('users', {
'id': 1,
'name': 'John Doe',
});
// Delete it
await crdt.setDeleted('users', [1]);
// Or merge a remote dataset
await crdt.merge({
'users': [
{
'id': 2,
'name': 'Jane Doe',
'hlc': Hlc.now(uuid()).toString(),
},
],
});
// Queries are simple SQL statements, but notice:
// 1. the CRDT columns: hlc, modified, is_deleted
// 2. Mr. John Doe appears in the results with is_deleted = 1
final result = await crdt.query('SELECT * FROM users');
// Perhaps a better query would be
final betterResult =
await crdt.query('SELECT id, name FROM users WHERE is_deleted = 0');
// We can also watch for results to a specific query, but be aware that this
// can be inefficient since it reruns watched queries on every database change
crdt.watch('SELECT id, name FROM users WHERE is_deleted = 0').listen(print);
// Update the database
await crdt.update('users', [2], {'name': 'Jane Doe 👍'});
// Undelete Mr. Doe
await crdt.setDeleted('users', [1], false);
// Create a changeset to synchronize with another node
final changeset = await crdt.getChangeset();
```

## Usage: Reading Data

Queries are standard SQL fare with three columns required for the CRDT functionality: `hlc` `modified` `is_deleted`


* In most cases you'll want to filter out deleted data by adding `WHERE is_deleted = 0` to your queries
* There's a `watch` method that emits results whenever the database changes, but it is inefficient since it just reruns the query whenever the database changes

## Features and bugs

Please file feature requests and bugs at the [issue tracker](https://github.com/cachapa/sqlite_crdt/issues).
6 changes: 6 additions & 0 deletions analysis_options.yaml
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include: package:lints/recommended.yaml

linter:
rules:
prefer_single_quotes: true
unawaited_futures: true
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