How to solve TypeError: result.select is not a function in a Node.JS, Express JS and MongoDB App-CodePudding

I am creating a store API.

I am trying to filter out the result using the field from req.query and select. Everything else works fine except the select.

Error: TypeError: result.select is not a function

if (field) {
        const sortField = field.split(",").join(" ");
        result = result.select(sortField);
    }

Not sure why is the select not a function.

CodePudding user response：

From the image, looks like result is a unresolved promise when you call the select. Also, there's no select method for an array (witch I believe, is what you're trying to filter out); instead you can use filter

Try this:

let newResult;
if (field && result) {
        const sortField = field.split(",").join(" ");
        newResult = result.filter(x=> x === sortField);
}

CodePudding user response：

Try with:

let products;
if (field) {
    products = await product.find(queryObject).select(field.split(',').join(' '));
} else {
    products = await product.find(queryObject);
}
res.status(200).json({ products, number: products.length });