Functions stored in array will be shown as nulls

[DaniilVysotskiy]

We have some abstract method in class, like this:

class SomeClass {
    constructor() {
        this.dataListeners = {};
    }

    someAbstractMethod (topic, eventFn) {
      if (!Array.isArray(this.dataListeners[topic])) {
        this.dataListeners[topic] = [];
        ...
      }
      ...
      this.dataListeners[topic].push(eventFn);
      this.logger.info('Listeners to topic', this.dataListeners[topic]); // --> output is { ...,"msg":"Listeners to topic [null]","v":1}

      return this;
    }
}

this.dataListeners[topic] actually stores the functions, but somehow pino interpreters those as nulls. Same message shown via console.log() is proper:

Listeners to topic [ [Function: onIncomingTask] ]

What am I doing wrong?

[rusekr]

Half day stuck because of these nulls in logged arrays!

[mcollina]

the msg text should be fixed to ease processing/searching.

Add those as a property.

log.info({ hello: “world” }, “some log line”)

I don’t recall if we did this for some purpose or not, there were definitely some differences in interpolation. Maybe would you like to send a PR? What do you think @davidmarkclements?

[davidmarkclements]

this is something we can improve in the mean time a workaround for this scenario would be to convert the functions to strings yourself

this.logger.info('Listeners to topic', this.dataListeners[topic].map(({name}) => `[Function: ${name}]`));

[zaunermax]

Stumbled across this today, is there any other workaround than the one david mentioned above? Having to do this in every log is quite cumbersome expecially when using typescript as I want to print out whole objects and and data mangling them to print out function names is quite a hassle tbh :thinking:

[jsumners]

Use a hook -- https://github.com/pinojs/pino/blob/613d700fc2b77768bbbc84095a5cc28fb745b10d/docs/api.md#logmethod

[Fdawgs]

Use a hook -- https://github.com/pinojs/pino/blob/613d700fc2b77768bbbc84095a5cc28fb745b10d/docs/api.md#logmethod

Resolved by this.

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