Solving File Path Errors in Node.js: Lessons Learned
Tags: node, javascript, devjournal, tutorial
Published: 2023-02-28 12:23:42

Working with file paths in Node.js can be tricky and can cause errors if not handled correctly. In this article, I'll discuss the issues I faced while comparing CSV files and how I resolved it.

## Background

I was comparing two CSV files using a JavaScript Node.js tool I created, where I used the built-in fs module and a well-known CSV parser library called csv-parser. The plan was to parse the files and compare them programmatically.

```jsx
const fs = require("fs");
const csv = require("csv-parser");

const currentProducts = [];

fs.createReadStream("../../../../Downloads/current_products.csv")
  .pipe(csv())
  .on("data", (data) => {
    currentProducts.push(data["Product ID"]);
  })
  .on("end", () => {
    console.log(currentProducts);
  });
```

## The Issue

While executing the above code, I encountered the following error:

`Error: ENOENT: no such file or directory, open '../../../../Downloads/current_products.csv`

![File path error message](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/bp35q4pyw4lsrifsxdxp.png)

## Troubleshooting and Simple Fix

After some debugging, I realised that Node.js uses the current working directory for resolving file paths rather than the location of the actual script file. In my case, the script file was located in a different directory than the one I was executing the code from.

To fix this issue, I had two options:

- Ensure that the current working directory (`cwd`) is the same as where the script is located, and then run the file.
- OR Use absolute paths / environment variables for the file paths.

I chose the second option by using the `path` module to create an absolute path for me. 

```jsx
const fs = require("fs");
const csv = require("csv-parser");
const path = require("path");

const currentProductsFile = path.resolve(
  `${__dirname}`,
  "../../../../Downloads/current_products.csv"
)

const currentProducts = [];

fs.createReadStream(currentProductsFile)
  .pipe(csv())
  .on("data", (data) => {
    currentProducts.push(data["Product ID"]);
  })
  .on("end", () => {
    console.log(currentProducts);
  });
```

`path.resolve()` resolves a sequence of paths or path segments into an absolute path. It's useful when working with file paths, providing a reliable way to get the absolute path of a file or directory regardless of the script's location. 

`__dirname` in Node.js is a global variable that represents the directory name of the current module.

### Best Practice

It's always a good practice to know the current working directory of the script, which can be checked by logging `process.cwd()`. It's also recommended to use absolute paths or environment variables to ensure that the code works reliably across different directories and machines.

The Node.js `path` module is a great tool to help with building paths, so it's worth checking out.

In summary, when working with file paths in Node.js:

- Remember that Node.js executes from the current working directory.
- Relative paths will resolve based on the current working directory.
- A way to check the current working directory is to log `process.cwd()`
- Try to use absolute paths or environment variables to avoid issues like this.
- The Node.js `path` module can help with building absolute paths.

By following these best practices, you can avoid errors and ensure that your code works reliably across different directories and machines.


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