Internal Should not be instantiated by the user.
Internal _propagationReadonly commandThe command object. Equal to the response body of the HTTP request.
Note that this is the actual raw command object; it's not necessarily 1:1 with methods called on the collection/db.
{
insertOne: { document: { name: 'John' } }
}
Readonly commandThe command name.
This is the key of the command object. For example, if the command object is
{ insertOne: { document: { name: 'John' } } }, the command name is insertOne.
Readonly extraAny extra information that may be useful for debugging.
Readonly keyspaceThe keyspace the command is being run in.
Readonly nameThe name of the event (e.g., 'CommandStarted', 'CommandFailed').
Protected Internal permitsPoor man's sealed class. See BaseClientEvent.permits for more info.
Readonly requestA unique identifier for the request that triggered this event.
It helps correlate multiple events occurring within the same request lifecycle.
High-level operations, such as collection.insertMany(...), may generate multiple requests internally. Each of these requests will have its own unique requestId.
As an example, a CommandStarted event may be emitted when a command is started, and a CommandSucceeded event may be emitted when the command has succeeded. Both of these events will have the same requestId.
If logged to a file (e.g. winston with a file transport and json format), you could then filter all events with the same requestId to see the entire lifecycle of a single command.
// Set up event listeners on the collection
collection.on('commandStarted', (e) => {
console.log(`Command started with requestId: ${e.requestId}`);
});
collection.on('commandSucceeded', (e) => {
console.log(`Command succeeded with requestId: ${e.requestId}`);
});
// Logs:
// - Command started with requestId: dac0d3ba-79e8-4886-87b9-20237c507eba
// - Command succeeded with requestId: dac0d3ba-79e8-4886-87b9-20237c507eba
await collection.insertOne({ name: 'Alice' });
// Logs:
// - Command started with requestId: 1fe46a92-8187-4eaa-a3c2-80a964b68eba
// - Command succeeded with requestId: 1fe46a92-8187-4eaa-a3c2-80a964b68eba
await collection.insertOne({ name: 'Bob' });
Optional Readonly sourceThe table/collection the command is being run on, if applicable.
Readonly targetThe target of the command.
Readonly timeoutThe timeout for the command, in milliseconds.
Readonly timestampThe timestamp of when the event was created.
Readonly urlThe URL the command is being sent to.
Static Protected Internal formatProtected _extraFormats the event into a human-readable string, as it would be logged to stdout/stderr (if enabled).
See EventFormatter & BaseClientEvent.setDefaultFormatter for more information about custom formatting.
Optional custom formatter function.
The formatted event string.
Converts the event to a verbose JSON format, as it would be logged to stdout:verbose/stderr:verbose (if enabled).
Useful for debugging. The output is pretty-printed JSON with newlines, so perhaps not ideal for structured logging though.
A JSON string with full event details.
Stops the event from bubbling up to the parent listener (e.g. Collection → Db → DataAPIClient) and prevents any further listeners from being called.
db.on('commandStarted', (e) => {
console.log('Command started (db listener)');
});
collection.on('commandStarted', (e) => {
console.log('Command started (collection listener #1)');
e.stopImmediatePropagation();
});
collection.on('commandStarted', (e) => {
console.log('Command started (collection listener #2)');
});
// Logs:
// - Command started (collection listener #1)
collection.insertOne({ name: 'Alice' });
stopPropagation
Stops the event from bubbling up to the parent listener (e.g. Collection → Db → DataAPIClient).
client.on('commandStarted', (e) => {
console.log('Command started (client listener)');
});
db.on('commandStarted', (e) => {
console.log('Command started (db listener)');
e.stopPropagation();
});
collection.on('commandStarted', (e) => {
console.log('Command started (collection listener)');
});
// Logs:
// - Command started (collection listener)
// - Command started (db) listener
collection.insertOne({ name: 'Alice' });
stopImmediatePropagation
Static setSets the default formatter for all events.
Useful especially if you want to change the format of events as they're logged to stdout/stderr (see LoggingOutputs).
See EventFormatter for much more info.
This method sets a static property on the class, so it will affect all instances of BaseClientEvent, regardless of the class. Be careful when using this method in a shared environment.
A function that transforms an event into a log string.
BaseClientEvent.setDefaultFormatter((event, msg) => `[${event.name}] ${msg}`);
Emitted when a command is started, before the initial HTTP request is made.
Note that these emit real commands, not any abstracted commands like "insertMany" or "updateMany", which may be split into multiple of those commands under the hood.
See CommandEvent for more information about all the common properties available on this event.