README

mongoose-model-stream

a mongoose model generator with a change stream

info:

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Install

yarn add mongoose-model-stream

npm install --save mongoose-model-stream

How to Use

const moduleStream = require('mongoose-model-stream');

constructor

This moduleStream function takes two arguments.

modelName: The name of the model
schema : The schema definition of the model.

There is also an optional 3rd argument.

options OR enableDownStream
- options: the options object that will be passed to the change stream schema. You can set enableDownStream as a Property on options
- enableDownStream: A boolean to change will create change events, without listening to the stream for updates. (Default: true)

const ChatSchema = new mongoose.schema({
  text: String
});

const Chat = moduleStream('Chat', ChatSchema);

Attached to Chat will be a .stream baced on RxJs. This will emit change events baced on rfc6902

The payload looks like:

Property	Type	Description
patchs	Array	Present for all changes to the item. - An array of rfc6902 operations.
target	String(ID)	The Unique identifier for the target Object
_id	String(ID)	The Unique identifier for this diff
createdAt	String(Date)	The time the chage was made
action	String	This will be "CREATE", "UPDATE" or "DELETE" depending on the state of the document in the database

model

Create

A new function will be added to the model

saveBy : This is used the tag a change with who made it.

event.when = "today";
event.saveBy(user);

A saveBy id will be add to the change record

Outputted change

{ patchs:
   [ {
     op: 'add',
     path: '/when',
     value: 'today'
   } ],
  _id: '5a958d12fc413a44ac760fb1',
  target: '5a958d11fc413a44ac760fa9',
  saveBy: '5a95872c39c0be3afaeb9a86',
  createdAt: '2018-08-12T04:46:02.009Z',
  action: "UPDATE"
}

Update

"saveBy" is also provided in the update function(s)
- update, updateMany, updateOne, findOneAndUpdate, findByIdAndUpdate

You said the "saveBy" bypassing it in the "options" argument. This can be an ID of an object(String) that will be used for all patchs or a function to calculate the ID for each specific updated document

const conditions = {foo:true },
updateValues = {setBarTo:false},
options = {savedBy:(oldDoc,newDoc,patchs)=>oldDoc.user_id}
event.updateMany(conditions,update,options)

run samples

node example/sample.js

Example

require('mongoose-model-stream');
const { Schema, moduleStream } = require('mongoose');

// create a schema
const ChatSchema = new Schema({ text: String }, { timestamps: true });

// create a module
const Chat = moduleStream('Chat', ChatSchema);

// subscribe to change events
Chat.stream.subscribe(console.log, console.error, console.info);

Chat.create({ text: "foo" })
    .then(function (chatMessage) {
        chatMessage.text = "bar";
 return chatMessage.save();
    }).then(function (chatMessage) {
        chatMessage.text = "baz";
        chatMessage.save();
    }).catch(console.error);

Output:

Change: 1

{ patchs:
   [ {
     op: 'add',
     path: '/text',
     value: :'foo'
   }, {
     op: 'add',
     path: '/_id',
     value: '5a86eea992f78d54f1cd65e9'
   }, {
     op: 'add',
     path: '/updatedAt',
     value: :'2018-08-12T04:46:01.993Z'
   }, {
     op: 'add',
     path: '/createdAt',
     value: '2018-08-12T04:46:01.993Z'
   }  ],
  _id: '5a86eeaa92f78d54f1cd65ea',
  target: '5a86eea992f78d54f1cd65e9',
  createdAt: '2018-08-12T04:46:02.009Z',
  action: "CREATE"
}

Change: 2

{ patchs:
   [ { op: 'test', path: '/updatedAt', value: '2018-08-12T04:46:01.993Z' },
     { op: 'replace', path: '/text', value: 'bar' },
     { op: 'replace', path: '/updatedAt', value: '2018-08-12T04:46:02.116Z' }, ],
  _id: '5a86eeaa92f78d54f1cd65eb',
  target: '5a86eea992f78d54f1cd65e9',
  createdAt: '2018-08-12T04:46:02.022Z',
  action: "UPDATE"
 }

Change: 3

{ patchs:
   [ { op: 'test', path: '/updatedAt', value: '2018-08-12T04:46:02.116Z' },
     { op: 'replace', path: '/text', value: 'baz' },
     { op: 'replace', path: '/updatedAt', value: '2018-08-12T04:46:02.342Z' }, ],
  _id: '5a86eeaa92f78d54f1cd65ec',
  target: '5a86eea992f78d54f1cd65e9',
  createdAt: '2018-08-12T04:46:02.122Z',
  action: "UPDATE"
 }

Usage no npm install needed!