https://github.com/stefanhengl/fields

Like select-keys but for nested maps
https://github.com/stefanhengl/fields

clojure fields filter nested select-keys

Last synced: 6 months ago
JSON representation

Like select-keys but for nested maps

• Host: GitHub
• URL: https://github.com/stefanhengl/fields
• Owner: stefanhengl
• License: mit
• Created: 2019-08-03T16:41:15.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2019-08-18T04:57:46.000Z (over 6 years ago)
• Last Synced: 2025-06-09T02:12:11.755Z (7 months ago)
• Topics: clojure, fields, filter, nested, select-keys
• Language: Clojure
• Homepage:
• Size: 10.7 KB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

          
# fields [![Build Status](https://travis-ci.com/stefanhengl/pdfsplit.svg?branch=master)](https://travis-ci.com/stefanhengl/pdfsplit)

`fields` exposes the function `select-keys-by-fields` which offers the

same functionality as

[select-keys](https://clojuredocs.org/clojure.core/select-keys) but

for complex nested maps. Instead of specifying paths in a vector, we write a query

describing the structure of the desired output map.

`fields`is inspired by the same-named HTTP request parameter as

described by Google

[here](https://developers.google.com/drive/api/v3/performance). In the

background it parses the query into a

[zipper](https://clojuredocs.org/clojure.zip) and traverses the zipper

filtering the map along the way.

## Example

```clojure

(def data {:a 1

	   :b [{:aa 2 :bb 3} {:aa 4 :bb 5}]

	   :c {:cc 6 :dd {:fff 7 :ggg 8}}})

(select-keys-by-fields data "(a)")

=> {:a 1}

(select-keys-by-fields data "(a,b(aa))")

=> {:a 1, :b ({:aa 2} {:aa 4})}

(select-keys-by-fields data "(b,c(cc,dd(ggg)))")

=> {:b ({:aa 2, ::bb 3} {:aa 4, :bb 5}), :c {:cc 6, :dd {:ggg 8}}}

```

The parser which parses a query string and outputs a zipper is a pure function that is worth caching whenever you have many differnt maps but only a small set of queries. For such use cases you can just memozie the parser and use `select-keys-by-zipper` instead of `select-keys-by-fields`.

``` clojure

(def parse-memo (memoize parse))

(select-keys-by-zipper data (parse-memo "(a,b(aa))"))

=> {:a 1, :b ({:aa 2} {:aa 4})}

```

## Latest Version

[![Clojars Project](https://img.shields.io/clojars/v/fields.svg)](https://clojars.org/fields)

## License

 MIT