access the info of the user that created the post - node.js

Question

I am making a react-native mobile app and I am having trouble passing the users info that created the post to the home page in the post detail. I can pass the userID but for some reason when I add the rest of the info to the payload I can't create a post. Please help.
BACKEND
This is the requireAuth file that requires authentication before performing a tast. My code for the user is here as well at the bottom---
const mongoose = require("mongoose");
const User = mongoose.model("User");
module.exports = (req, res, next) => {
const { authorization } = req.headers;
if (!authorization) {
return res.status(401).send({ error: "You must be logged in." });
}
const token = authorization.replace("Bearer ", "");
jwt.verify(token, "mySecretKey", async (err, payload) => {
if (err) {
return res.status(401).send({ error: "You must be logged in." });
}
const { userId, name, phone, email } = payload;
const user = await User.findById(userId);
req.user = user;
console.log(req.user);
next();
});
};
This is the POST route for the Item---
router.post("/items", requireAuth, async (req, res) => {
const { title, category, detail, condition, price } = req.body;
if (!title || !category || !detail || !condition || !price) {
return res.status(422).send({
error: "You must provide a title, category, detail, condition, and price"
});
}
try {
const item = new Item({
title,
category,
detail,
condition,
price,
userId: req.user._id
});
await item.save();
res.send(item);
} catch (err) {
res.status(422).send({ error: err.message });
}
});
FRONT-END
This is my createItem function in the itemContext file---
const createItem = dispatch => async ({
title,
category,
detail,
condition,
price
}) => {
try {
const response = await sellerApi.post("/items", {
title,
category,
detail,
condition,
price
});
//this is the other place the error might be happening i need this to save in the phone local storage
dispatch({ type: "create_item", payload: response.data });
navigate("Home");
} catch (err) {
console.log(err);
}
};
All I am trying to do it is when the post is being displayed so is the info of the post creator

Answer 1

For existing post in the database: If you are referencing your user in post model like this
const Post = mongoose.model('Post', {
// other fields
userId: {
type: mongoose.Schema.Types.ObjectId,
required: true,
ref: 'User'
}
})
then you can use populate to fetch user of that post.
const post= await Post.findById('5c2e505a3253e18a43e612e6')
await post.populate('userId').execPopulate()
console.log(post.userId)