Realm is a mobile database that runs directly inside phones, tablets or wearables. This project hosts the JavaScript versions of Realm. Currently, we support React Native (JSC & Hermes on iOS & Android), Node.js and Electron (on Windows, MacOS and Linux).
- Mobile-first: Realm is the first database built from the ground up to run directly inside phones, tablets and wearables.
- Simple: Data is directly exposed as objects and queryable by code, removing the need for ORM's riddled with performance & maintenance issues.
- Modern: Realm supports relationships, generics, and vectorization.
- Fast: Realm is faster than even raw SQLite on common operations, while maintaining an extremely rich feature set.
- MongoDB Atlas Device Sync: Makes it simple to keep data in sync across users, devices, and your backend in real time. Get started for free with a template application and create the cloud backend.
Please see the detailed instructions in our docs to use Realm JavaScript for Node.js and Realm JavaScript for React Native. Please notice that currently only Node.js version 13 or later is supported. For React Native users, we have a compatibility matrix showing which versions are supported.
It is exciting to have users, and we want to support you as good as possible. Our community support (Github issues in this and our related repositories) is divided into three tiers, and below you can see which packages, versions and platforms we consider for the different tiers.
If you want to contribute to any of our packages, you are welcome to do so. We will take the time to review your pull request for any package.
In tier 1 we will respond to issues in a timely manner during workdays from CET timezone, and we will work on bug fixing and adding new features.
- Realm JavaScript (NPM tag:
latest) on node.js (LTS) and Electron on Windows, MacOS, and Linux - Realm JavaScript (NPM tag:
latest) with the latest React Native version 0.71.0 on Android and iOS - @realm/react (NPM tag:
latest) in conjunction with the latest Realm JavaScript release
Some packages are considered to be mature and stable, and we will support them as good as we can when time permits.
- Realm Web (NPM tag:
latest) - Realm Studio (latest release) on Windows, MacOS, and Linux
- Any other release of Realm JavaScript not covered by tier 1
The third tier covers our experimental packages. We work on them occasionally, and they are likely to change radically when we do.
The documentation for the Realm React Native SDK can be found at mongodb.com/docs/realm/sdk/react-native/. The documentation for Realm Node.js SDK can be found at mongodb.com/docs/realm/sdk/node.
The API reference is located at docs.mongodb.com/realm-sdks/js/latest/.
If you are using React Native, please also take a look the README for @realm/react, which provides React hooks to make working with Realm easier.
TypeScript is a popular alternative to pure JavaScript as it provide static typing. Our TypeScript support consists of two parts
- Accurate TypeScript definitions @realm/babel-plugin to transform TypeScript classes to Realm schemas. An example of a model class is:
class Task extends Realm.Object<Task, "description"> {
_id = new Realm.BSON.ObjectId();
description!: string;
@index
isComplete = false;
static primaryKey = "_id";
constructor(realm, description: string) {
super(realm, { description });
}
}Realm is a general SDK which provide you persistence of objects and the capability to perform advanced queries on the objects. You can have tighter integration with React Native by using @realm/react.
Moreover, we have a Flipper plugin to help you inspect, query and modify your Realm files while debugging your app on a simulator or a physical device. The plugin is still in an early stage so expect rough edges.
We have TypeScript templates to help you get started using Realm. Follow the links to your desired template and follow the instructions there to get up and running fast.
- Need help with your code?: Look for previous questions on the #realm tag — or ask a new question. You can also check out our Community Forum where general questions about how to do something can be discussed.
- Have a bug to report? Open an issue. If possible, include the version of Realm, a full log, the Realm file, and a project that shows the issue.
- Have a feature request? Open an issue. Tell us what the feature should do, and why you want the feature.
See CONTRIBUTING.md for more details!
- Realm is not compatible with the legacy Chrome Debugger. The following debugging methods are supported:
- Flipper has many similar features in relation to the Chrome Debugger.
- Safari also has a similar feature set, but requires some setup and only supports debugging in iOS.
- NOTE: For the above methods, it is not necessary to enable
Debug with Chromein the Debug Menu.
For instructions on building Realm JS yourself from the source, see the building.md file.
Some users have reported the Chrome debugging being too slow to use after integrating Realm into their react-native project. This is due to the blocking nature of the RPC calls made through the Realm library. See realm#491 for more information. The best workaround is to use Safari instead, as a user has described here.
Moreover, we have a switch to Flipper in the works as part of our effort to support Hermes. It implies that we envision a near future where the Chrome debugging will be removed, and we currently don't invest much in its maintenance.
It's possible after installing and running Realm that one encounters the error Could not find the Realm binary. Here are are some tips to help with this.
Consult our COMPATIBILITY.md to ensure you are running compatible version of realm with the supported versions of node, react-native or expo.
Typically this error occurs when the pod dependencies haven't been updating. Try running the following command
npx pod-install
If that still doesn't help it's possible there are some caching errors with your build or your pod dependencies. The following commands can be used to safely clear these caches:
rm -rf ios/Pods
rm ios/Podfile.lock
rm -rf ~/Library/Developer/Xcode/DerivedData
Afterwards, reinstall pods and try again. If this still doesn't work, ensure that node_modules/realm/react-native/ios/realm-js-ios.xcframework exists and contains a binary for your architecture. If this is missing, try reinstalling the `realm`` npm package.
This can occur when installing realm and not performing a clean build. The following commands can be used to clear your cache:
cd android
./gradlew clean
Afterwards, try and rebuild for Android. If you are still encountering problems, ensure that node_moduels/realm/react-native/android/src/main/jniLibs contains a realm binary for your architecture. If this is missing, try reinstalling the realm npm package.
If you are using Expo, a common pitfall is not installing the expo-dev-client and using the Development Client specific scripts to build and run your React Native project in Expo. The Development Client allows you to create a local version of Expo Go which includes 3rd party libraries such as Realm. If you would like to use realm in an Expo project, the following steps can help.
- install the
expo-dev-client:npm install expo-dev-client - build the dev client for iOS
npx expo run:ios - build the dev client for Android
npx expo run:android - start the bundler without building
npx expo start --dev-client
When running npm install realm the realm binaries for the detected architecture are downloaded into node_modules/realm/prebuilds. If this directory is missing or empty, ensure that there weren't any network issues reported on installation.
Asynchronously submits install information to Realm.
Why are we doing this? In short, because it helps us build a better product
for you. None of the data personally identifies you, your employer or your
app, but it will help us understand what language you use, what Node.js
versions you target, etc. Having this info will help prioritizing our time,
adding new features and deprecating old features. Collecting an anonymized
application path & anonymized machine identifier is the only way for us to
count actual usage of the other metrics accurately. If we don’t have a way to
deduplicate the info reported, it will be useless, as a single developer
npm install-ing the same app 10 times would report 10 times more than another
developer that only installs once, making the data all but useless.
No one likes sharing data unless it’s necessary, we get it, and we’ve
debated adding this for a long long time. If you truly, absolutely
feel compelled to not send this data back to Realm, then you can set an env
variable named REALM_DISABLE_ANALYTICS.
Currently the following information is reported:
- What version of Realm is being installed.
- The OS platform and version which is being used.
- If a JavaScript framework (currently React Native and Electron) is used and its version.
- Which JavaScript engine is being used.
- Node.js version number.
- TypeScript version if used.
- An anonymous machine identifier and hashed application name to aggregate the other information on.
Moreover, we unconditionally write various constants to a file which we might use at runtime.
This project adheres to the MongoDB Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to community-conduct@mongodb.com.
Realm JS and Realm Core are published under the Apache License 2.0.
If you use Realm and are happy with it, all we ask is that you please consider sending out a tweet mentioning @realm to share your thoughts
And if you don't like it, please let us know what you would like improved, so we can fix it!
Made with contrib.rocks.