每当我尝试通过 Heroku 运行我的服务器时，我都会收到“错误：找不到模块 'dotenv'”

Question

Browsing stack overflow, I noticed that a common fix is make sure that dotenv is in dependencies and not just devDependencies. Here's a screenshot of the log and the package.json . You'll notice that dotenv is indeed in my dependencies. I also deleted and reinstalled node_modules multiple times but still no luck.

I am requiring the dotenv at the top of my server file as shown here

Answer 1

Can you post any necessary code please?

Answer 2

I fixed the issue. I decided to try uninstalling dotenv and reinstalling, this worked. Apparently, this was different from deleting node modules and npm install.

Answer 3

I see dotenv is added to a devDependency : devDependency are special and are only installed when you do a npm install on the package.json which contains them. Usually, you'll add your development tooling (like test runners, etc.) in devDependencies since they are not required for the application to run.

When we run an application in production, we install dependencies using npm install --production which only installs the dependencies mentioned in the dependencies section of package.json . This is also what Heroku does for you (check their buildpack for Node.js!)

To install a devDependency , you would do: npm i -D <package name> ; and to install a production dependency (like your web framework like express ), you'd do npm i -S express .

Try running npm i -D dotenv and check if it works (it may also work if you just do a npm i dotenv .