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I wrote a simple application using node. It depends on express, mongodb and mongoose (easy). So, I created a file called package.json and put this in it:

{ "name": "booking-dojo", "description": "Booking dojo app", "version": "0.0.1", "private": true, "dependencies": { "express": "3.x", "mongodb": "*", "mongoose": "*" } }

I then ran npm install, expecting npm to install those modules and their dependencies. The result was disappointing:

[email protected] /home/merc/Synced/Development/Bookings/app/server ├─┬ [email protected] │ ├── [email protected] │ ├─┬ [email protected] │ │ ├── [email protected] │ │ ├── [email protected] │ │ ├── [email protected] │ │ └── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ └─┬ [email protected] │ └── [email protected] ├─┬ [email protected] │ └── [email protected] └─┬ [email protected] ├── [email protected] └── [email protected]

I am confused by this, as I know that express needs jade (and much more), and mongoose needs mongodb.
If I go into node_modules/jade and run npm install, the result from the main tree is very different:

[email protected] /home/merc/Synced/Development/Bookings/app/server ├─┬ [email protected] │ ├── [email protected] │ ├─┬ [email protected] │ │ ├── [email protected] │ │ ├── [email protected] │ │ ├── [email protected] │ │ └── [email protected] │ ├─┬ [email protected] │ │ └─┬ [email protected] │ │ └── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├─┬ [email protected] │ │ └── [email protected] │ ├─┬ [email protected] │ │ └── [email protected] │ ├── [email protected] │ ├── [email protected] │ ├─┬ [email protected] │ │ ├── [email protected] │ │ ├── [email protected] │ │ └─┬ [email protected] │ │ └── [email protected] │ ├── [email protected] │ ├─┬ [email protected] │ │ └── [email protected] │ ├── [email protected] │ ├─┬ [email protected] │ │ └── [email protected] │ └─┬ [email protected] │ └─┬ [email protected] │ ├── [email protected] │ ├── [email protected] │ ├── [email protected] │ └── [email protected] ├─┬ [email protected] │ └── [email protected] └─┬ [email protected] ├── [email protected] └── [email protected]

So, express has grown a lot. It looks like npm install is only loading some of the dependencies of the sub-modules.

Can somebody please shed some light on this? Why are some dependencies missing? Am I doing something wrong? (likely)

Thanks!

Merc.

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3 Answers 3

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38

You are confused about at least 2 points.

First, express does not depend on jade, as you can see by reading the node_modules/express/package.json file:

 "dependencies": { "connect": "2.4.2", "commander": "0.6.1", "range-parser": "0.0.4", "mkdirp": "0.3.3", "cookie": "0.0.4", "crc": "0.2.0", "fresh": "0.1.0", "methods": "0.0.1", "send": "0.0.3", "debug": "*" }

Express does, however, work with jade if it is available, as well as many other template engines. So to fix this list jade as a dependency in your package.json file and you'll be fine.

Second, npm only installs node packages, not third party things like mongodb. You need to install mongodb and any other dependencies that are not npm modules using other means (apt-get, yum, manual install, etc).

So npm DOES install dependencies recursively, but only npm modules.

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3 Comments

Another thing to note is that if a package depends on a module that can be resolved further up in the dependency chain, it will. For example, since you have mongodb in your package.json, Mongoose doesn't need to install its own mongodb.
Brandon, this is the answer. I just figured it out not long ago. Basically, it doesn't install MongoDb under Mongoose because it's resolved further up. Since this is the actual answer, can you please add it as a proper answer, rather than a comment, so that I can accept it?
@Peter Good point, applications generated by express will have however express as a dependency BTW. My question, "why are some dependencies missing?", has the simple answer (provided by Brandon) "They are missing because they are resolved further up in the dependency tree". Thanks!
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The answer was provided by Brandon in a comment to another answer:

"Another thing to note is that if a package depends on a module that can be resolved further up in the dependency chain, it will. For example, since you have mongodb in your package.json, Mongoose doesn't need to install its own mongodb. – Brandon Tilley 2 days ago

Thank you Brandon! (And this is the answer...)

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5

use this sample

{ "name": "app", "version": "0.0.1", "main":"test.js", "author":"Test", "description": "For test ", "dependencies": { "express": "latest", "mongoose": "latest" } }

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