advanced-results

Middleware used for advanced querying Mongoose Documents for a specific Model through GET request using the queries and parameters provided by the URL . It only works with MongoDB (mongoose) and expressjs. Furthermore, it includes pagination

Why use this middleware?

Benefits:

1. Advanced query for specific field in mongoose model
2. Many available operators and operations that you can use just by passing them in the URL
3. Special operators like ?all and ?q that provide global advanced query/search through all fields in a mongoose model without worrying about what type is the field(Mongoose String, Mongoose ObjectId) or the query value(number, string, date)
4. Included Pagination

Additional examples about this middleware: HERE

Install

$ npm install advanced-results@latest

Usage

ES6 syntax:

import advancedResults from 'advanced-results'

ES5 syntax:

const advancedResults = require('advanced-results');

Basic usage

Advanced-results middleware is very easy to implement you just use it in the route right before your main controller/middleware: Ex.

const app = express();

app.use('/posts', advancedResults(Model), (req, res) => {
  // The result for the advancedResults middleware is store inside res.advancedResults
  res.status(200).json({ success:true, data: res.advancedResults })
});

The results and the chosen documents are stored inside res.advancedResults. Ex num2.

const router = express.router();

router.get('/posts', advancedResults(Model), (req, res) => {
  // The result for the advancedResults middleware is store inside res.advancedResults
  res.status(200).json(res.advancedResults)
});

How it works

This middleware works thanks to the express request object and uses req.query and req.params.

As a first argument advancedResults(MODEL), accepts a mongoose model that will be the target for the advanced querying.

Example scenario:

1. Model

 const UserSchema = new mongoose.Schema({
    name: String,
    user: String,
    randomNum: Number,
  });

  const User = mongoose.model('User', UserSchema);

  await model.insertMany([
      { name: 'Tester', user: 'Tester', randomNum: 4 },
      { name: 'Tester2', user: 'Tester2', randomNum: 54 },
      { name: 'Tester3', user: 'Tester3', randomNum: 42 },
    ]);

1. Route:

  app.use(
    '/users',
    advancedResults(User),
    (req, res: any) => {
      res.status(200).json(res.advancedResults);
    }
  );

1. URLs:

  FOR URL: example.com?name=Tester

  OUTPUT: res.advancedResults = {
  success: true,
  count: 1,
  pagination: { pages: 1, total: 1, maxDocuments: 3, current: 1, limit: 6 },
  data: [
    {
      _id: 5fa47738c49e1327502760ca,
      name: 'Tester',
      user: 'Tester',
      randomNum: 4,
      __v: 0
    }
  ]
}

  FOR URL: example.com?name[regex]=Tester

  OUTPUT: res.advancedResults = {
  success: true,
  count: 3,
  pagination: { pages: 1, total: 3, maxDocuments: 3, current: 1, limit: 6 },
  data: [
    {
      _id: 5fa47738c49e1327502760ca,
      name: 'Tester',
      user: 'Tester',
      randomNum: 4,
      __v: 0
    },
    {
      _id: 5fa47738c49e1327502760cb,
      name: 'Tester2',
      user: 'Tester2',
      randomNum: 54,
      __v: 0
    },
    {
      _id: 5fa47738c49e1327502760cc,
      name: 'Tester3',
      user: 'Tester3',
      randomNum: 42,
      __v: 0
    }
  ]
}

  FOR URL: example.com?name[regex]=Tester&select=name

  OUTPUT: res.advancedResults = {
  success: true,
  count: 3,
  pagination: { pages: 1, total: 3, maxDocuments: 3, current: 1, limit: 6 },
  data: [
    { _id: 5fa47738c49e1327502760ca, name: 'Tester' },
    { _id: 5fa47738c49e1327502760cb, name: 'Tester2' },
    { _id: 5fa47738c49e1327502760cc, name: 'Tester3' }
  ]
}

URLs also work with some special fields: all, q and filter
Example 1.

  FOR URL: example.com?all=42

  OUTPUT: res.advancedResults = {
  success: true,
  count: 1,
  pagination: { pages: 1, total: 1, maxDocuments: 3, current: 1, limit: 6 },
  data: [
    {
      _id: 5fa47738c49e1327502760cc,
      name: 'Tester3',
      user: 'Tester3',
      randomNum: 42,
      __v: 0
    }
  ]
}

?all or ?q fields are basically the same and they are used for searching trough all paths and subpaths of the provided model. For the query above where ?all=42 here's what was given to the model.find() function:

model.find({ '$or': [ { randomNum: 42 }, { __v: 42 } ] })

Example 2 for ?all or ?q:

  FOR URL: example.com?all=test&select=name&sort=name

  QUERY PASSED TO MODEL(USER in our case):
  model.find("$or":[{"name":{"$regex":"test","$options":"i"}},{"user":{"$regex":"test","$options":"i"}}])

  OUTPUT: res.advancedResults = {
  success: true,
  count: 3,
  pagination: { pages: 1, total: 3, maxDocuments: 3, current: 1, limit: 6 },
  data: [
    { _id: 5fa47738c49e1327502760ca, name: 'Tester' },
    { _id: 5fa47738c49e1327502760cb, name: 'Tester2' },
    { _id: 5fa47738c49e1327502760cc, name: 'Tester3' }
  ]
}

?filter is a more complicated query parameter and requires more parsing before it's sent to the backend. I initially created this option because of react-admin package. You can find more example on how to use this HERE

Advance Usage

Additional parameters

advancedResults except model as first parameter it takes 3 more arguments

advancedResults(Model, populateFieldOrFields: string | string[], parameter: [string, string], consoleLogIt: boolean)

1. First parameter is the model that will be used by this middleware on a certain route
2. If in the model you have ObjectId field that can be populated you can pass that field as the second argument in this function and res.advancedResults will return the matching documents with that populated field.
   Example. advancedResults(User, 'blogs') OR if you have multiple fields that you want to populate you do advancedResults(User, ['blogs', 'books'])
3. The third argument is specific argument and is used to handle the case where we have a route that has parameter inside of it: example.com/posts/:userId. So the third argument ALWAYS is array with length of 2. The first element of that array is the field NAME and the second is the parameter NAME. Example.
   If lets say model Post has an users field inside of it that is of type ObjectId you pass the ['users', 'userId] ---> it will create additional filter in this case if the parameter's userId = 1234567afd (example.com/posts/123456afd), object will be {users: 1234567afd}.
   This can be used with additional query example.com/posts/123456afd?all=text&limit=2&page=3
   advancedResults(Post, null, ['user', 'userId'])
4. The fourth argument is of type boolean and is only used for deciding whenever the middleware should console log what the final results of res.advancedResults will look like and what will be passed to model.find(). Default is: fasle
   advancedResults(Post, null, null, true)

Documentation

In this section I will mention most of the options you can pass to the URL that will work with this middleware

Options

Check MongoDB documentation about querying, operators and options in order to understand more about this middleware. Here's a basic explanation for some of the options :

Field Specific Operators

1. Operators that you can pass to the URL without $ sign:

Operator	Description
in	selects the documents where the value of a field equals any value in the specified array , ex. ?field[in]=value1,value2
regex	provides regular expression capabilities for pattern matching strings in queries. By default is in-case sensitive but can be changed by the $options operator, ex. ?field[regex]=sth)
options	this only works with regex. By default is case-insensitivite ex. ?field[regex]=val&field[options]=i
gt	example.com?field[gt]=5
gte	example.com?field[gte]=5
lt	example.com?field[lt]=5
lte	example.com?field[lte]=5
eq	example.com?field[eq]=5

1. Other operators work however you need to pass $ for example, if you want to pass operator $ne. You need to do example.com?field[$ne]=value. All operators HERE: https://docs.mongodb.com/manual/reference/operator/

Query operations

Special operations that can be done via URL:

Operations	Description
select	selects single or multiple fields from a document, example.com?select=field or multiple example.com?select=field1,field2
sort	Default field: createdAt, example.com?sort=field. Field can be ?sort=name (ASC Order) or ?sort=-name (DSC Order) or ?sort=randomNum,-name (sorting multiple fields)
limit	default: 6, used for limiting documents affects pagination object inside res.advancedResults, example.com?limit=5
page	default: 1, the current page (if there are multiple pages), this goes together with ?limit, and depending on the ?page and ?limit values it calculates and displays the current pagination properties inside res.advancedResults, ex. example.com?page=2
all or q	used for searching trough all fields of provided model for a certain value provided in the URL, ex. example.com?all=value or multiple words example.com?all=value1+value2
filter	more complex than the other 2, it requires additional parsing before sending request to backend to work. Short explanation: filter is an object that first needs to be JSON.stringified then using library like query-parser, parsed INTO URL then sent to the backend. Check this additional explanation for usage

Result: res.advancedResults explained in Details

Usually res.advancedResults is provided in the next form:

res.advancedResults = {
  success: true,
  count: 3,
  pagination: {
    pages: 3,
    total: 9,
    maxDocuments: 3,
    next: { nextPage: undefined, page: 2 },
    current: 1,
    limit: 1
  },
  data: [
    {
      _id: 5fa47738c49e1327502760ca,
      name: 'Tester',
      user: 'Tester',
      randomNum: 4,
      __v: 0
    },
    {
      _id: 5fa47738c49e1327502760cb,
      name: 'Tester2',
      user: 'Tester2',
      randomNum: 54,
      __v: 0
    },
    {
      _id: 5fa47738c49e1327502760cc,
      name: 'Tester3',
      user: 'Tester3',
      randomNum: 42,
      __v: 0
    }
  ]
}

• count - returns the number of documents currently in the data object. This is not the same as pagination.maxDocuments or pagination.total
• pagination - object depends on the ?page and ?limit. The next property gives the next page (if there's one) and the next next Page if it exists. If next.page exists, however next.nextPage doesn't it is set to undefined. Example if page = 1; next.page = 2; next.nextPage = 3 | undefiend. Same explanation is with the prev property of the pagination object
• pagination.total - the maximum number of documents with the QUERY
• pagination.maxDocuments - the maximum number of documents without the QUERY. So this the total number of document from that model
• data - The result of model.find(), a list of all documents that match the specific query criteria. If none it is empty

Additional explanation about ?all or ?q

If you have ?all=word1+word2 it does query for every field for word1 + for word2 + both words "word1 word2" and merges them together into a single object which is then passed to model.find()

What to do if you still don't understand how it works?

I would encourage you to install this middleware and enable the console log option which is the fourth argument and see what it returns and what will be taken into consideration when querying.

Error handling

If this middleware throws an error it will automatically call next(new Error) which will then go to your error middleware handler. Check expressjs error handling page where it teaches you how to define error middleware to handle all types of error and return them into the res object back to the client

Some cheat codes for the ones that made it to the end

Instead of manually adding let's say parameters to URL example: localhost?name=Tester1&select=name. You can do that with stringified object. Here's how you do that:

const query = {
    all: "Test",
    select: "name",
    page: "2"
}

Now you need to use additional library like query-string to stringify object to be transformed into valid URL parameters

const queryString = require('query-string');

const URL = `http://localhost:5000?${queryString.stringify(query)}`;

await axios.get(URL);

The query string transforms my URL variable to -> http://localhost:5005?all=Test&select=name&page=2 accordingly

CHECK THE ADDITIONAL DOCS FOR MANY MORE EXAMPLES AND EXPLANATION ON HOW TO USE THE ?filter PARAMETeR