make npm.load re-evaluate the cwd each time it is called

[trusktr]

I'd like to change the cwd of npm after it's been loaded. For example, I've got something like this, where I run npm.load and npm.command.install twice, Meteor.wrapAsync just causes the execution to be "synchronous":

            fs.existsSync(path.resolve(DIR_ONE, 'node_modules')) // false
            fs.existsSync(path.resolve(DIR_TWO, 'node_modules')) // false

                process.chdir(DIR_ONE)
                Meteor.wrapAsync((callback) =>
                    npm.load({}, () => callback(null, 'blah'))
                )()
                Meteor.wrapAsync((callback) => {
                    npm.commands.install([], () => callback(null, 'blah'))
                })()

            fs.existsSync(path.resolve(DIR_ONE, 'node_modules')) // true
            fs.existsSync(path.resolve(DIR_TWO, 'node_modules')) // false
            shell.exec('rm -rf '+path.resolve(DIR_ONE, 'node_modules')) // start over
            fs.existsSync(path.resolve(DIR_ONE, 'node_modules')) // false
            fs.existsSync(path.resolve(DIR_TWO, 'node_modules')) // false

                process.chdir(DIR_TWO)
                Meteor.wrapAsync((callback) =>
                    npm.load({}, () => callback(null, 'blah'))
                )()
                Meteor.wrapAsync((callback) => {
                    npm.commands.install([], () => callback(null, 'blah'))
                })()

            fs.existsSync(path.resolve(DIR_ONE, 'node_modules')) // true again
            fs.existsSync(path.resolve(DIR_TWO, 'node_modules')) // still false

The second time, npm doesn't install inside of DIR_TWO as expected. How can we change npm's cwd?

[trusktr]

I see that Meteor uses child_process to manipulate the CLI version on NPM. Maybe that's what I'll have to do. It would be cool to easily change npm dir programmatically though.

[trusktr]

Aha, found the solution that (as far as my case goes) works:

            Meteor.wrapAsync((callback) => {
                npm.load({ prefix: DIR_ONE }, callback)
            })()
            Meteor.wrapAsync((callback) => {
                npm.commands.install(DIR_ONE, [], callback)
            })()

...

            Meteor.wrapAsync((callback) => {
                npm.load({ prefix: DIR_TWO }, callback)
            })()
            Meteor.wrapAsync((callback) => {
                npm.commands.install(DIR_TWO, [], callback)
            })()

Now, I don't know if the prefix value is changing between these two npm installs, but luckily both prefixes contain the same package.json, so even if the second location get installed based on the first prefix, it works out.

[trusktr]

Actually, re-opening, as I think that the second call to npm.load should re-evaluate the cwd.

[othiym23]

The current programmatic API for npm is unsupported for use outside itself, and there are no guarantees that it will remain stable or has any particular fitness for purpose. If you want to invoke multiple npm commands from another program, the best thing to do is to call npm as a child process twice. At some point, we'll have a better interface for using the installer programmatically, but we're not there yet. As such, I'm closing this.