Error handling

Linz consistently manages all errors by passing the error through to next. This allows a consistent approach to error handling and provides a centralised approach to intercept those errors if desired.

Linz provides an error handling middleware at linz.api.middleware.error. You should mount this to your Express app as the last piece of error middleware. It will:

• Log err.stack to console.error.
• Store the error at req.linz.error.
• Return the error in the context of JSON, or display the error in a view.

Recording errors

You can use some middleware to trap all errors that happen within Linz. For example:

module.exports = (req, res, next) => {

    res.on('finish', () => {

        if (req.complete && req.linz && req.linz.error) {
            console.error(req.linz.error);
        }

    });

    return next();

};

JSON errors

If an error occurs within Linz, in the context of a JSON request, Linz will decorate the error with two properties:

• json will be true.
• statusCode will be 500.

If the Linz error handling middleware captures an error with those properties, will return the error via JSON.