project.md

$project

Import

const $project = require("mongo-to-sql").$project;

or

const $project = require("mongo-to-sql/stages/project");

Syntax

$project(stage, tableName, options);

Options

• headless
  • Boolean
  • Defaults to false
  • When specified as true, it will remove the FROM keyword and the assosiated table name from the generated query.
• tableCounter
  • Integer
  • When not specified or specified as 0, it will cause the table name to be escaped.
  • If it is greater than 0, the table name will not be escaped as it is assumed to be a subquery.

Similarities to MongoDB

• If you exclude fields, you cannot also specify the inclusion of fields.
• Fields with expressions will automatically have their expressions converted to their appropriate forms.

Differences with MongoDB

• The _id field is not included by default.

Supported operators

---

• $concat
• $toLower
• $toUpper

Field Inclusion

$project({
    "field1": 1,
    "field2": 1
}, "tableName");

Field Exclusion

$project({
    "field1": 0,
    "field2": 0
}, "tableName");

$concat

$project({
    "concatenatedFieldName": {
        "$concat": [ "$field1", " - ", "$field2" ]
    }
}, "tableName");

$toLower

$project({
    "lowercaseFieldName": {
        "$toLower": "$field1"
    },
    "lowercaseFieldName2": {
        "$toLower": "HELLO WORLD"
    }
}, "tableName");

$toUpper

$project({
    "uppercaseFieldName": {
        "$toUpper": "$field1"
    },
    "uppercaseFieldName2": {
        "$toUpper": "hello world"
    }
}, "tableName");