This library exports a function getQuery which takes a data-structure as query and returns an Postgres SQL query to retrieve nested data in JSON form.

Here is an example of a JSON query

  {
    "table_name": {
      "fields": {
        "id": "table_id"
      },
      "children": {
        "other_table": {
          "fields": {
            "id": "other_id"
          }
        }
      },
      "conditionString": "example_number = 1",
      "conditions": { "boolean_field": true, "number_field": "> 5" }
    }
  }

table_name - is the name of the table querying

children - is an embedded query neste under the current table

conditions - contains field keys with values that the field should equal. A leading '=' is implied if an operator is not specified.

conditionString - raw unprocessed condition.

import getQuery from 'pg-nested-json-query'

{
const query = {
  "table_name": {
    "fields": {
      "id": "table_id"
    },
    "children": {
      "other_table": {
        "fields": {
          "id": "other_id"
        }
      }
    },
    "conditionString": "example_number = 1",
    "conditions": {
      "boolean_field": true,
      "number_field": "> 5"
    }
  }
}


console.log( getQuery( query ) )

Output

select json_build_object(
  'table_name', array(
    select json_build_object(
      'id', table_name.table_id,
      'other_table', array(
        select json_build_object(
          'id', other_table.other_id
        ) from other_table where other_table.table_id = table_name.table_id
      )
    ) from table_name where table_name.boolean_field = true and table_name.number_field > 5 and example_number = 1
  )
)

This package provides a CLI in bin directory that can accept either a JSON, JSON6, or YAML file as a query and writes and Postgres SQL query to STDIN.

Example use

npx pg-nested-json-query web-query.yaml | psql database > web-data.json

Here is the help screen for CLI tool

Usage

  pg-nested-json-query query-file [options]

Options

  --file file       This is the default option and can be omitted.
  --type, -t type   Declare file format. Either "yaml", "json" or "json6".
  --help, -h        Opens this help screen, all other options are ignored.

Copyright 2018 Babak Badaei

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