Declarative style JSON objects converter

Features

• Self descriptive template language
• Simple syntax for flattening hierarchical objects
• Possibility to mix declarative and imperative styles

Install

npm install t-objects

Usage example

const T = require("t-objects").T;

const company = {
  Departments: [
    {
      Name: "Quality assurance",
      Staff: [
        {
          FirstName: "Panic",
          LastName: "Generator",
          Position: "QA-Engineer",
        },
        {
          FirstName: "Ivanov",
          LastName: "Ivan",
          Position: "QA-Engineer",
        },
      ],
    },
    {
      Name: "Development",
      Staff: [
        {
          FirstName: "Bydlo",
          LastName: "Coder",
          Position: "Junior Developer",
        },
        {
          FirstName: "Nebydlo",
          LastName: "Coder",
          Position: "Senior Developer",
        },
      ],
    },
  ],
};

const t = T({
  "->": true,
  $company: ":external",
  "{$dep}": ["$company", (c) => c.Departments],
  "{$person}": ["$dep", (d) => d.Staff],
  FirstName: ["$person", (p) => p.FirstName],
  LastName: ["$person", (p) => p.LastName],
  Position: ["$person", (p) => p.Position],
  Department: ["$dep", (d) => d.Name],
});

console.log(t.build({ $company: company }));

Output

[
  {
    FirstName: "Panic",
    LastName: "Generator",
    Position: "QA-Engineer",
    Department: "Quality assurance",
  },
  {
    FirstName: "Ivanov",
    LastName: "Ivan",
    Position: "QA-Engineer",
    Department: "Quality assurance",
  },
  {
    FirstName: "Bydlo",
    LastName: "Coder",
    Position: "Junior Developer",
    Department: "Development",
  },
  {
    FirstName: "Nebydlo",
    LastName: "Coder",
    Position: "Senior Developer",
    Department: "Development",
  },
];

API reference

T Class

Constructor

Params

• template Object - Template object

Returns

• T - Class instance

build

Params

• data Object - Input data object

Returns

• Object - Output data object

Language reference

Special keys

• -> - Template marker or initial queue. Any object in template that has this marker will be processed by build method. Marker may be set in boolean true value or predefined keys queue. Predefined keys queue will be corrected or appended by properties dependencies.

• $<string> - Service property. These properties may be used as temporary variables and will be deleted at the end of processing.

• ? - Condition. If this property is falsy parent object will be rejected from output data object.

• {<value>, <index>, <total index>} - Variety. Property constructor must return array of values for this key. In this case parent object will be expanded in collection of objects. Every element of this collection will be parent object extended by new <value>, its <index> and <total index> (if parent has already become a collection).

• $return - Replace object with this property. Replaces parent object with this property.

• : - Key of object. Replaces array for multiinstance object.

• $parent - Parent object.

• $root - Root object.

Special values

• :external - Find value of this key in input data.

Property constructor notation

• ['key1', 'key2', ... 'keyN', function(key1, key2, ... keyN) { ... }] - Property constructor.

• 'key1', 'key2', ... 'keyN' - dependencies. One may mark dependency as mandatory or critical.

• 'key*' - mandatory. In this case, if value of key is undefined, constructor will not be called.

• 'key**' - critical. In this case, if value of key is undefined, build_error exception will be thrown.

  This notation also works in singular forms: [function() { ... }] and function() { ... }