Data persistency

By default data is stored in memory. This means the data is flushed when the server restarts. To persist your data, provide the connectionString config setting for your JSON file(s) or MongoDB database.

connectionString accepts either a string shorthand (simple, great for quick setups) or a DataSourceConfig object (structured, full TypeScript autocomplete).

How Temba determines the storage type from a string:

Temba inspects the connectionString value to decide which adapter to use:

1. MongoDB: Starts with "mongodb" → MongoDB database
2. Single JSON file: Ends with ".json" → Single file for all resources
3. Directory of JSON files: Matches /^[a-zA-Z0-9_-]+$/ → Folder with one file per resource
4. Fallback: Any other value → In-memory storage

Both the JSON file and folder paths are resolved relative to the directory from which you start the server.

JSON file

All resources are stored in a single JSON file with the structure:

{
  "movies": [{ "id": "1", "title": "..." }, ...],
  "actors": [{ "id": "2", "name": "..." }, ...]
}

The file is created automatically when the first resource is added (POST).

String shorthand

const server = await create({
  connectionString: 'data.json',
})

Object form

const server = await create({
  connectionString: { type: 'file', filename: 'data.json' },
})

Folder of JSON files

To store each resource in its own JSON file, use a folder name. Each resource will be saved in a separate JSON file inside the folder, created on demand when data for that resource is first added. For example:

• data/movies.json — Contains an array of movie objects
• data/actors.json — Contains an array of actor objects

Valid folder names for the string shorthand: Only alphanumeric characters, hyphens, and underscores are allowed (e.g., "data", "my_data", "api-db").

String shorthand

const server = await create({
  connectionString: 'data',
})

Object form

const server = await create({
  connectionString: { type: 'folder', folder: 'data' },
})

MongoDB

String shorthand

const server = await create({
  connectionString: 'mongodb://localhost:27017/myDatabase',
})

Object form

const server = await create({
  connectionString: { type: 'mongodb', uri: 'mongodb://localhost:27017/myDatabase' },
})

For every resource you use in your requests, a collection is created in the database. However, not until you actually create a resource with a POST.

The object form also lets you configure additional MongoDB connection options without embedding them in the URI:

MongoDB with extra options

const server = await create({
  connectionString: {
    type: 'mongodb',
    uri: 'mongodb://localhost:27017/myDatabase',
    username: 'alice',
    password: 's3cr3t',
    authSource: 'admin',
    tls: true,
    tlsCAFile: '/certs/ca.pem',
    maxPoolSize: 10,
    serverSelectionTimeoutMS: 5000,
  },
})

The full set of available MongoDB options:

Option	Type	Description
uri	string	MongoDB connection URI (required)
username	string	Username for authentication
password	string	Password for authentication
authSource	string	Authentication database (defaults to 'admin')
tls	boolean	Enable TLS/SSL
tlsCAFile	string	Path to the CA certificate file
tlsCertificateKeyFile	string	Path to the client certificate/key file
tlsAllowInvalidCertificates	boolean	Allow invalid TLS certificates (not recommended for production)
maxPoolSize	number	Maximum connections in the connection pool
minPoolSize	number	Minimum connections in the connection pool
serverSelectionTimeoutMS	number	Timeout (ms) for server selection
connectTimeoutMS	number	Timeout (ms) for initial connection
replicaSet	string	Replica set name
readPreference	string	Read preference (e.g. 'primary', 'secondary', 'nearest')
writeConcern	string	Write concern (e.g. 'majority')