herbertscruz / loopback-single-query

Creates a single SQL query from the loopback filters.

loopback-single-query

The loopback-connector-juggler is a fantastic ORM/ODM that perfectly meets all database query needs. However, when we work with relational databases and include many relationships in the root filter object or its scope, we notice a very large loss of performance.

The loopback-single-query creates a single SQL query from the Loopback Filters to solve these cases. By optimizing tables and relationships in your database, performance gains can achieve impressive results.

Supported

This library was tested with Loopback version 2.39.0 and MySQL 5.7.25. Contributions are welcome.

Usage

Install:

npm install loopback-single-query

On need:

const filter = {
  "include": [
    {"relation": "relation1"},
    {"relation": "relation2"},
    {"relation": "relation3"},
    {"relation": "relation4"},
    {
      "relation": "relation5",
      "scope": {
        "include": [
          {
            "relation": "subrelation1",
            "scope": {
              ...
            }
          },
          ...
        ]
      }
  "fields": {
    "id": true,
    "title": true
  }
  "where": {
    "and": [
      {"title": {"like": "%Term%"}},
      {"type": {"inq": [1, 3]}},
      {"description": null},
      {"id": {
        "and": [
          {"neq": 100},
          {"gte": 1000}
        ]
      }
    ]
  },
  "order": ["title ASC", "created DESC"],
  "limit": 1,
  "skip": 10,
  
};

const app = require('server/server');
const SingleQuery = require('loopback-single-query');

// Promise
const ps = SingleQuery.find(app.models.Model, filter);
ps.then(console.log);
ps.catch(console.error);

// OR

// Callback
SingleQuery.find(app.models.Model, filter, (err, data) => {
  if (err) return console.error(err);
  console.log(data);
});

Debug

You can analyze everything the loopback-single-query is doing in the background as with debug as follows:

DEBUG=single-query* node .

Debug strings reference

Module / Source file	String
lib/single-query.js	single-query
lib/query-builder.js	single-query:query-builder
lib/parse-to-model.js	single-query:parse-to-model