Express middleware to set a correlation id per route in express. The correlation id will be consistent across async calls within the handling of a request.
From v3 onwards this library requires node >=16. For older node versions use v2.x.
npm i express-correlation-id --saveAll middleware and route handlers following the correlator() middleware will be within a single correlation scope. If the incoming request has a header called x-correlation-id then it's value will be used as the id for this request, otherwise the id will be a new uuid.
Note: the correlator middleware should be placed after any other middleware.
const correlator = require('express-correlation-id');
const express = require('express');
const app = express();
// app.use other middleware here
app.use(correlator());
app.get('/', (req, res) => {
console.log('ID for this request is:', req.correlationId()); // id for this request
console.log('ID for this request is:', correlator.getId()); // equal to above, not dependant on the req object
res.end();
});Returns an express middleware that creates a correlation scope for all following middleware and route handlers. If the incoming request has a header with name x-correlation-id then it's value will be used as the id. The header name is configurable, see options below.
To ensure the correlation id is available to other middleware, ensure that it's applied after them.
const app = express();
// app.use other middleware here
app.use(correlator());Options to configure the correlator middleware.
Configures the name of the inbound header to check for a correlation id.
const app = express();
app.use(correlator({ header: 'x-my-correlation-header-name' }));Returns the id for the current request. If called outside of a request returns undefined. This function is useful if you don't want to pass the req object or correlation id from the handler to downstream code.
correlator.getId(); // Returns the current id or undefinedReturns the id for the current request. This function is added to the incoming req by the middleware.
req.correlationId(); // Returns the current idSets the id for the current request. If called outside of a request throws and error. Useful if you
need to set the correlatiaon id and don't want to pass req object from the haandler to downstreama code.
correlator.setId('my-new-id');Sets the id for the current request. This function is added to the incoming req by the middleware.
req.setCorrelationId('my-new-id');MIT