flutter_mimir

A batteries-included NoSQL database for Dart & Flutter based on an embedded Meilisearch instance.

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Features

• 🔎 Typo tolerant and relevant full-text search with no extra configuration needed
• 🔥 Blazingly fast search and reads (written in Rust)
• 🤝 Flutter friendly with a super easy-to-use API (see demo below!)
• 🔱 Powerful, declarative, and reactive queries
• 🔌 Cross-platform support
• 🉑️ Diverse language support, including CJK, Hebrew, and more!

Getting Started

1. Install rustup, for Rust, on your development computer
2. Run flutter pub add mimir flutter_mimir for Flutter or dart pub add mimir for Dart-only
3. For Flutter macOS apps, disable "App Sandbox"
4. Read the caveats below

Demo

With Flutter, you can get started with as little as:

// Get an "index" to store our movies
final instance = await Mimir.defaultInstance;
final index = instance.getIndex('movies');

// Add movies to our index
await index.addDocuments(myMovies);

// Perform a search!
final results = await index.search(query: 'jarrassic par'); // returns Jurassic Park!

Sponsors

You can become a sponsor of my work here!

Reference Documentation

A collection of commonly used APIs ready for copy-paste into your application.

Note: unless otherwise stated, all asynchronous methods exposed in Mimir are fallible and synchronous methods are infallible. The methods are fail-fast, so you should be aware of any issues early on during development.

Getting & Creating an Index

// With Flutter (flutter_mimir)
final instance = await Mimir.defaultInstance;

// Dart-only (just mimir)
final instance = await Mimir.getInstance(path: instanceDirectory); 

// Get an index (creates one lazily if not already created)
final index = instance.getIndex('movies');

// Or, specify some default settings and open the index eagerly
// If you have some settings you want to specify in advance, use openIndex!
final index = await instance.openIndex('movies', primaryKey: 'CustomIdField');

Configuring an Index

await index.updateSettings(
  // The primary key (PK) is the "ID field" of documents added to mimir.
  // When null, it is automatically inferred for you, but sometimes you may
  // need to specify it manually. See the Important Caveats section for more.
  primaryKey: null,
  // Fields in documents that are included in full-text search.
  // Use null, the default, to search all fields
  searchableFields: <String>[],
  // Fields in documents that can be queried/filtered by.
  // You probably don't need to change this; it is automatically
  // updated for you.
  filterableFields: <String>[],
  // Fields in documents that can be sorted by in searches/queries.
  // You probably don't need to change this; it is automatically
  // updated for you.
  sortableFields: <String>[],
  // The ranking rules of this index, see:
  // https://docs.meilisearch.com/reference/api/settings.html#ranking-rules
  rankingRules: <String>[],
  // The stop words of this index, see:
  // https://docs.meilisearch.com/reference/api/settings.html#stop-words
  stopWords: <String>[],
  // A list of synonyms to link words with the same meaning together.
  // Note: in most cases, you probably want to add synonyms both ways, like below:
  synonyms: <Synonyms>[
    (
      word: 'automobile',
      synonyms: ['vehicle'],
    ),
    (
      word: 'vehicle',
      synonyms: ['automobile'],
    ),
  ],
  // Whether to enable typo tolerance in searches.
  typosEnabled: true,
  // The minimum size of a word that can have 1 typo.
  // See minWordSizeForTypos.oneTypo here:
  // https://docs.meilisearch.com/reference/api/settings.html#typo-tolerance-object
  minWordSizeForOneTypo: 5,
  // The minimum size of a word that can have 2 typos.
  // See minWordSizeForTypos.twoTypos here:
  // https://docs.meilisearch.com/reference/api/settings.html#typo-tolerance-object
  minWordSizeForTwoTypos: 9,
  // Words that disallow typos. See disableOnWords here:
  // https://docs.meilisearch.com/reference/api/settings.html#typo-tolerance-object
  disallowTyposOnWords: <String>[],
  // Fields that disallow typos. See disableOnAttributes here:
  // https://docs.meilisearch.com/reference/api/settings.html#typo-tolerance-object
  disallowTyposOnFields: <String>[],
);

Manipulating Documents

// Adding documents (replaces any documents with the same id)
await index.addDocument(document);
await index.addDocuments(documents);

// Replacing all documents
await index.setDocuments(documents);

// Deleting documents
await index.deleteDocument(id);
await index.deleteDocuments(ids);
await index.deleteAllDocuments();

// Getting documents (not querying--see next section!)
final docOrNull = await index.getDocument(someId);
final allDocs = await index.getAllDocuments();
final allDocsStream = index.documents;

Searching/Querying

// Getting a stream of results (very useful in Flutter!)
// Same arguments as index.search; see below
final documentsStream = index.searchStream(...);

// Performing a search/query (using movies here)!
final movies = index.search(
  // The string to use for full-text search. Can be user-supplied.
  // To do a regular database query without full-text search, leave this null.
  query: 'some wordz with typoes to saerch for',
  // The filter used to filter results in a full-text search or query.
  // See the next section; this is a very handy feature in mimir.
  // Set to null to not filter out any documents.
  filter: Mimir.where('director', isEqualTo: 'Alfred Hitchcock'),
  // The fields to sort by (in ascending or descending order).
  // Can be left as null to sort by relevance (to the query text)!
  sortBy: [
    // Sort by year, newest to oldest
    SortBy.desc('year'),
    // In case 2+ documents share the same year, sort by increasing profit next
    SortBy.asc('profit'),
  ],
  // If you want to limit the number of results you get, use the resultsLimit.
  // Defaults to null, which means return all matches.
  resultsLimit: null,
  // Defaults to null, see https://docs.meilisearch.com/reference/api/search.html#matching-strategy
  matchingStrategy: null,
);

Filtering Search/Query Results

Here are the methods you need to be aware of:

• Mimir.or(subFilters) creates an "or" filter (like ||) of the sub-filters
• Mimir.and(subFilters) creates an "and" filter (like &&) of the sub-filters
• Mimir.not(subFilter) creates a "not" filter (like !someCondition) of the sub-filter
• Mimir.where(condition) creates a single filter from a given condition.
• The above can be composed together to create powerful, declarative queries!

Say our Dart boolean logic is (formatted to show intent):

(
    (
        (movie['fruit'] == 'apple')
        &&
        (movie['year'] >= 2000 && movie['year'] <= 2009)
    )
    ||
    movie['colors'].any((color) => {'red', 'green'}.contains(color))
)

Here's what our filter composition would look like:

final filter = Mimir.or([
  Mimir.and([
    Mimir.where('fruit', isEqualTo: 'apple'),
    Mimir.where('year', isBetween: ('2000', '2009')),
  ]),
  Mimir.where('colors', containsAtLeastOneOf: ['red', 'green']),
])

Mimir's filters also support "dot syntax" for nested fields, e.g.:

Mimir.where('content.title', isEqualTo: 'foobar')

Important Caveats

Please read these caveats before adding mimir to your project.

• Every document in mimir needs to have a "primary key"
  • The PK is automatically inferred via a field ending in id (or simply just id)
  • If you have multiple fields ending in id, use instance.openIndex('indexName', primaryKey: 'theActualId')
  • The contents of the PK field can be a number, or a string matching the regex ^[a-zA-Z0-9-_]*$
    • In English: PKs can be alphanumeric and contain - and _
• Unfortunately, you can only open 1 index on iOS devices; see here for more details and a workaround.
• macOS App Sandbox is not supported, meaning you will not be able to submit apps to the Mac App Store
  • You will still be able to distribute macOS applications on your own
  • See more details here
• Resource usage
  • While modern devices run mimir just fine, several thousand detailed documents can easily consume several MB of disk space and RAM
  • This is due to Milli, a heavy-weight core component of Meilisearch, which gives mimir a lot of its power
  • If you do not need all the features provided by mimir, also consider a more lightweight alternative!
    • Hive for simple key-value storage
    • Isar for more sophisticated use-cases
      • Note: while Isar does have full-text search, it is neither typo-tolerant nor relevant!
    • If you need easy, typo-tolerant, relevant full-text search, you will want mimir!
      • I am unaware of any other databases that currently provide typo-tolerant full-text search in Flutter, which is why I made mimir in the first place!
  • Mimir can add a couple hundred MB to your app bundle size and <100 MB to the on-device size
    • These numbers will hopefully be reduced in the future once Dart gets "Native Assets"