julienvincent/repath

A utility for repathing normalized data via JavaScript getters

repath

A utility for repathing or denormalizing normalized data using JavaScript getters.

Installation

$ yarn add repath

Explanation

It's often preferred to store data in a flat map instead of nesting it, however it's hard to work with data in this format as all references need to be manually reconstructed, or the data needs to go through some kind of denormalization process. Repath leaves your data in a flat map but replaces all entity references with getter functions that return the expected data.

Repath only ever parses the top of the data tree, any nested processing that may be required is done when the getters are invoked to prevent any unnecessary work.

Example

import repath from 'repath'

const data = {
   users: {
      1: {
         name: "John",
         book: 1
      }
   },
   
   books: {
      1: {
         title: "Book A",
         author: 1
      }
   }
}

const join = repath({
   schemas: {
      users: {
         __keys: ["author"]
      },
      books: {
         __keys: ["book"]
      }
   }
})

const parsedData = join(data)

// parsedData
{
   users: {
      1: {
         name: "John",
         book: [getter]
      }
   },
      
   books: {
     1: {
        title: "Book A",
        author: [getter]
     }
  }
}

// parsedData.users[1].book
{
   title: "Book A",
   author: [getter]
}

API

repath(config): parser

Invoke repath with some initial config. This will return a parser function.

config = {
   schemas: {
      rootA: {
         __keys: ["a", "b"] // array of property keys that are references to 'root',
         ...overrides // key => root properties that override the __keys of other roots. 
      },
      rootB: {
         __keys: [],
         b: "rootC", // instead of mapping b to rootA, map b to rootC
         a: null // specifying an override with value 'null' prevents any relationship mapping from occurring.
      },
      rootC: {
         ...
      }
   },
   unions: ["c", "d"], // array of properties that are unions of other schemas,
   
   /* By default, repath expects unions to be referenced by an object: {schema, id}.
    * If your union does not follow this pattern, you can provide a function to
    * infer the reference.
    * */
   inferReference: union => ({schema: string, id: string | number})
}

parser(data [, limiter]): Object

This is a function that will replace entity references with getter functions.

• data: Object - The collection of entities you want to parse
• limiter: Array<string> | string - Either a root or an array of roots to exclusively parse. All other roots will be ignored

Credits

Repath was inspired by a conversation with Alexis Vincent and was built as a collaboration.