如何将NPM模块（十进制）添加到ArangoDB以进行ACID事务

Question

I would like to do ACID Transactions with ArangoDB. And I would like to send the transaction Code (nodejs-code) to the ArangoDB server where it will then be executed and hopefully commited or rolled back if it fails. But at the ArangoDB serverside I need the NPM Decimal module or called package installed.

How do install it, and how do I access that particular module from the transaction code within?

Greetings and thanks.

Answer 1

Once you have the decimal module at the proper location and you can require it properly inside arangod, you should be able to use it inside a transaction like this:

db._executeTransaction({ 
  collections: { }, 
  action: function (params) { 
    var Decimal = require("decimal"); 
    return Decimal(params.foo).add(params.bar).toNumber(); 
  }, 
  params: { 
    foo: '1.1', 
    bar: '2.2' 
  } 
});

If your transactions need to access collection, you obviously need to specify their names in the "collections" attribute, eg

db._executeTransaction({ 
  collections: { 
    write: [ "test" ]
  }, 
  action: function (params) { 
    var Decimal = require("decimal");
    var collection = require("org/arangodb").db.test;
    var amount = Decimal(params.foo).add(params.bar).toNumber(); 

    return collection.save({ _key: params.key, amount: amount }); 
  }, 
  params: { 
    key: "mykey",
    foo: '1.1', 
    bar: '2.2' 
  } 
});

Answer 2

stj has already answered the transaction part of the question. Regarding installing NPM modules.

Switch into the folder

/usr/share/arangodb/js/common/node

and execute

npm install decimal

This should install the NODE module for both the server (arangod) and the shell (arangosh).