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Following the material on https://fullstackopen.com/en/part12/building_and_configuring_environments, when at the part "Persisting data with volumes", after spinning the containers up and visiting http://localhost:3000/todos, the error pops up.

MongooseError: Operation `todos.find()` buffering timed out after 10000ms

Followed the steps correctly and tried to debug with docker exec, the said database, collection and documents are all there, but when tried to retrieve using Mongoose, such error occurs.

EDITED:
After some troubleshooting, finally realized I have executed this line separately:

MONGO_URL=mongodb://the_username:the_password@localhost:3456/the_database```

```sh
npm run dev

instead of one whole line. Sorry to think that by splitting them up would achieve the same result, but it might be a good point to highlight to beginners especially those that are not too familiar with shell.

Thank you.

In Osa2 when first introducing lifecycle methods, componentDidMount is said to be called just before render is called for the first time
https://github.com/FullStack-HY/FullStack-Hy.github.io/blame/master/osa2.md#L1298

The same is said in Osa5, which references Osa2. Additionally, this is stated in Osa5

Kyseessä on siis ns. lifecycle-metodi, jota React-kutsuu juuri ennen kuin komponentti ollaan renderöimässä ensimmäistä kertaa.

https://github.com/FullStack-HY/FullStack-Hy.github.io/blame/master/osa5.md#L528

However, the official React docs state that componentDidMount is called after render is called. https://reactjs.org/docs/react-component.html#componentDidMount

Additionally the docs state

Calling setState() in this method will trigger an extra rendering, but it will happen before the browser updates the screen. This guarantees that even though the render() will be called twice in this case, the user won’t see the intermediate state.

So the method render is called before componentDidMount, but the actual rendering of the page, which is done by the browser, happens after it.

Could the authors clarify this part a bit, and possibly introduce componentWillMount, which is actually called before render?