mongodbrelation/README.md

ONE_TO_MANY, MANY_TO_ONE, ONE_TO_ONE, MANY_TO_MANY realtionships among diffrent collections in mongodb

# README #

Follow this for getting started

### What is this module for? ###

this module is used for using mongodb as sql database
we can perform joins among different collections of our mongodb database

### How do I get set up? ###
```
 npm install mongodbrelation
```
### NEW FEATUES I AM WORKING ON
* Nested Joins

### Who do I talk to? ###

* kamodh.pandey216@gmail.com

### FEATURES AVAILABLE
PERFORM JOINS AMONG DIFFERENT COLLECTIONS OF MONGODB

### USAGE
```json
<!-- authors collection -->
  [
   {"_id": 100, "name": "author 1"},
   {"_id": 102, "name": "author 2"},
   {"_id": 103, "name": "author 3"}
  ]

```
```json
 <!-- blogs collection -->
   [
    {"_id":1, "blogname": "blog1", "description":" blog description 1", "authorid": 100},
    {"_id":2, "blogname": "blog2", "description":" blog description 2", "authorid": 100}
   ]

```

### ONE_TO_ONE ###
let take an example of 
> ONE_TO_ONE
> i.e one blog belongs to one author

### so we need a query like get all blogs and join the author in blog document.<br/>
here parent is blog and child is author since author will be appended to blog<br/>
**condition: null (since we want all the blogs)**<br/> 
**joinCollectionName: authors (since we will join author to blogs)**<br/>
**joinFieldName: authorid (since parent is blog the key that is present in child is authorid)**<br/>
**foreignFieldName: _id  (authorid can be mapped to _id with author)**<br/>
**aliasname: authoralias (or what ever you prefer for the aliasname you can provide any string)**<br/>
**outputfields: null since we want to select all**<br/>
**typeofJoin: ONE_TO_ONE**<br/>

### IN Action for ONE_TO_ONE<br/>

```js
const mongodbrelation = require('mongodbrelation');
let query = mongodbrelation.joinedQuery(null,"authors", "authorid", "_id", "authoralias", null, "ONE_TO_ONE"); 
let dbquery = BlogModel.aggregate(query); // where BlogModel is mongoose Model Object
dbquery.exec(function(err, result) {
  console.log(result);
})
```
### CONSOLE OUTPUT
```json
[
  {
    "_id": 1,
    "blogname": "blog1",
    "description": " blog description 1",
    "authorid": 100,
    "createdAt": "2018-03-12T11:07:05.256+0000",
    "updatedAt": "2018-03-12T11:07:05.256+0000",
    "__v": 0,
    "authoralias": {
      "_id": 100,
      "name": "author 1",
      "createdAt": "2018-03-12T11:07:05.256+0000",
      "updatedAt": "2018-03-12T11:07:05.256+0000",
      "__v": 0
    }
  },
  {
    "_id": 2,
    "blogname": "blog2",
    "description": " blog description 2",
    "authorid": 100,
    "createdAt": "2018-03-12T11:07:05.256+0000",
    "updatedAt": "2018-03-12T11:07:05.256+0000",
    "__v": 0,
    "authoralias": {
      "_id": 100,
      "name": "author 1",
      "createdAt": "2018-03-12T11:07:05.256+0000",
      "updatedAt": "2018-03-12T11:07:05.256+0000",
      "__v": 0
    }
  }
]
```

### ONE_TO_MANY ###
let take an example of 
> ONE_TO_MANY
> i.e one author can write may blogs

### so we need a query like get author where authorid = 100 and append his/her blogs in blogalias <br/>
here parent is blog and child is author since author will be appended to blog<br/>
**condition: {"_id":100} (since we want the author where _id: 100)**<br/> 
**joinCollectionName: blogs (since we will join blogs to authors)**<br/>
**joinFieldName: _id (since parent is author and _id is present in child as collection blogs as authorid)**<br/>
**foreignFieldName: authorid  (authorid can be mapped to _id with authors collection)**<br/>
**aliasname: blogalias (or what ever you prefer for the aliasname you can provide any string)**<br/>
**outputfields: null since we want to select all**<br/>
**typeofJoin: ONE_TO_MANY**<br/>

### IN Action for ONE_TO_MANY<br/>

```js
  const mongodbrelation = require('mongodbrelation');
  var query = mongodbrelation.joinedQuery({_id: 100},"blogs", "_id", "authorid", "blogalias", null, "ONE_TO_MANY"); 
  let dbquery = AuthorsModel.aggregate(query); // where AuthorsModel is mongoose Model Object
  dbquery.exec(function(err, result) {
    console.log(result);
  })
```
### CONSOLE OUTPUT
```json
{
  "_id": 100,
  "name": "author 1",
  "createdAt": "2018-03-12T11:07:05.256+0000",
  "updatedAt": "2018-03-12T11:07:05.256+0000",
  "__v": 0,
  "blogalias": [
    {
      "_id": 1,
      "blogname": "blog1",
      "description": " blog description 1",
      "authorid": 100,
      "createdAt": "2018-03-12T11:07:05.256+0000",
      "updatedAt": "2018-03-12T11:07:05.256+0000",
      "__v": 0
    },
    {
      "_id": 2,
      "blogname": "blog2",
      "description": " blog description 2",
      "authorid": 100,
      "createdAt": "2018-03-12T11:07:05.256+0000",
      "updatedAt": "2018-03-12T11:07:05.256+0000",
      "__v": 0
    }
  ]
}

```


### Contribution guidelines ###

* Writing tests
* Code review
* Other guidelines