Develop Reference

Axios response data is not saved with useState

While trying to fetch data from my express backend and MySQL database, with my react frontend using axios, it fails to set the fetched data using useState
my frontend function looks like this
const searchUser = () => {
Axios.post("http://localhost:3001/searchUser", {
username: username,
}).then((response) => {
if (response.data) {
setResult(response.data);
}
});
};
and my backend function looks like this
const searchUser = (req, res) => {
const keyword = req.body.username;
db.query(
"SELECT id,username FROM users WHERE username like ?",
"%" + keyword + "%",
(err, result) => {
if (err) {
res.json({ message: err });
console.log(err);
} else {
console.log(result);
res.json({ result });
}
}
);
};
I tried many methods while saving the data with the useState hook, I appreciate any help

While using Promises and then instead of async / await make sure to catch the errors if your fetch fails.
Unless you share with us the whole component that contains the searchUser function and how you defined the state i cannot pin point you on the error.
What i suggest you to do is adding a catch to your fetch by doing the following:
const searchUser = () => {
Axios.post("http://localhost:3001/searchUser", {
username: username,
}).then((response) => {
if (response.data) {
setResult(response.data);
}
}).catch((error) => {
console.error(error);
});
};
If any abnormalities has happened in your request the catch will tell you! Don't underestimate it's power.
Another path you can look into is console logging your output in front end searchUser function just before setting it in the state.

I did solve the problem, just by replacing res.json({ result }); to res.json(result); in the last line in my backend function

How to pass information from Node to React

I have an object i need to parse to React.
I'm trying to get the "rows" object (in the node function) over to a React State.
The 2 piece of code below are on different pages!
The other issue is
GET http://localhost:3000/new net::ERR_CONNECTION_REFUSED
I am currently running these both locally
React http://localhost:3001/
Node - http://localhost:3000/
There have been SIMILAR questions to this but I can't find an answer with both issues!
Thanks
router.get("/new", (req, res) => {
let parentList = sql.fetchAllParents(function(err, rows) {
res.setHeader("Access-Control-Allow-Origin", "http://localhost:3001");
if (err) throw err;
res.render('new', {parents: rows});
});
});
componentDidMount() {
fetch(`http://localhost:3000/new`).then(response => {
console.log(response)
return response.json();
}).then(data => {
// Work with JSON data here
console.log(data,'data');
}).catch(err => {
// Do something for an error here
console.log("Error Reading data " + err);
});
}

Send response from node "new" api. Like this:
router.get("/new", (req, res) => {
......
......
res.send({status:200,parents:data})
});

How to add conditional checks over ORM (sequelizejs) queries?

Suppose i have a table gameData {gameId, currentBoardLayout}, a get request like www.chess.com/asd123 is sent over to the server, where asd123 is my game id, I need to catch this id (asd123 which is my gameId) and check for it in my table (gameData) and implement the following logic :
srv.get('/:id', (req, res) => {
if ( gameData.findAll({where: {gameId: req.params.id} )
{ // Game room found
return currentBoardLayout
}
else
{ error : Invalid game id }
})
How can I achieve this?
Thanks

You can use Sequelize's findById method.
srv.get('/:id', (req, res) => {
gameData.findById(req.params.id)
.then(result => {
res.send(result)
})
.catch(() => {
res.send({
error: 'Could not find ID'
})
})
})
Here's what is happening:
Sequelize's findById method will return a promise. If it successful, you will get your item from the database back. If the item cannot be found, the catch method will fire.
res.send is Express' way of sending data back to the client.
It is worth checking out the Sequelize docs:
Using models
Querying

Mongoose/Express Update Route Cast to Object ID issue

Working with Express and Mongoose, and I'm writing an Update route, and I seem to have hit a wall with this route. I've tried to find the object being requested via:
router.patch('/:insiderId', (req, res) => {
Insider.findById(req.params.insiderId)
.then(insider => {
insider = Object.assign({}, insider, req.body);
insider
.save()
.then(updated => {
res.json(updated);
})
.catch(err =>
res
.status(400)
.json({ error: 'error updating insider', originalError: err })
);
})
.catch(err => {
console.error(err);
res.status(400).json({
error: 'error finding insider to update.',
originalError: err
});
});
});
But I'm still given an error stating that Cast to ObjectId failed for value \"5b16d9e9119bef28908f49c\" at path \"_id\" for model \"insiders\"
I did a little reading, and thought that findById would automatically cast the objectid, but it doesn't appear to be doing that.
Is my code wrong?

I can`t delete anything from my MongoDB [duplicate]

I'm currently working on my first node.js rest api with express, mongodb (atlas cloud) and mongoose, when i try to make a .remove request i get this error:
{
"error": {
"name": "MongoError",
"message": "Cannot use (or request) retryable writes with limit=0",
"driver": true,
"index": 0,
"code": 72,
"errmsg": "Cannot use (or request) retryable writes with limit=0"
}
This is my request:
router.delete('/:productId', (req, res, next) => {
const id = req.params.productId;
Product.remove({ _id: id })
.exec()
.then(result => {
res.status(200).json(result);
})
.catch(err => {
console.log(err);
res.status(500).json({
error: err
})
}); ;
});

The findOneAndRemove() function would work more accordingly since its specific to the filtering method passed in the function .findOneAndRemove(filter, options) to remove the filtered object. Still, if the remove process is interrupted by the connection the retryRewrites=true will attempt the execution of the function when connected.
More information here
When using retryRewrites set to true tells the MongoDB to retry the same process again which in fact can help prevent failed connections to the database and operate correctly, so having it turn on is recommended.
More info here
If you are using Mongoose 5^ and MongoDB 3.6 your code is better written like:
mongoose.connect('mongodb.....mongodb.net/test?retryWrites=true', (err) => {
if(err){
console.log("Could not connect to MongoDB (DATA CENTER) ");
}else{
console.log("DATA CENTER - Connected")
}
});// CONNECTING TO MONGODB v. 3.6
router.delete('/:productId', (req, res, next) => {
const id = req.params.productId;
Product.findOneAndRemove({ _id: id })//updated function from .remove()
.exec()
.then(result => {
res.status(200).json({
message: "Product Removed Successfuly"
});
})
.catch(err => {
console.log(err);
res.status(500).json({
error: err
})
}); ;
});

I just changed the true to false in retryWrites=true and it worked. Is that a good approach? Or there is a better way to solve this problem?

retryWrites=true is a good thing, a workaround for this incompatibility is to use findOneAndRemove instead of remove (looks like you're using mongoose)