Ramda - how to get nested array values

Question

I am trying to get values from nested arrays using Ramda. I have multiple groups like in the example below. I need to get all children from all sections and all childrenWithoutSections in one array of strings.

const groups = [
   {
      "id":"10",
      "sections":[
         {
            "id":"1",
            "children":["10", "11"]
         },
         {
            "id":"2",
            "children":["12"]
         }
      ],
      "childrenWithoutSections":["1", "2"]
   },
   {
      "id":"11",
      "sections":[
         {
            "id":"3",
            "children":["13", "14"]
         },
         {
            "id":"4",
            "children":["15"]
         }
      ],
      "childrenWithoutSections":["3", "4"]
   }
]

I started with something like this:

R.pipe(
  R.pluck(['childrenWithoutSections']),
  R.flatten
)(groups)

And as a result, I got all the children from one required key but I have no idea how to get nested values from sections/children ?

Answer 1

As well as the suggestions in the comments, we can also write a point-free version of this:

 const extract = chain ( lift (concat) ( pipe (prop ('sections'), pluck('children'), flatten), prop ('childrenWithoutSections') ) ) const groups = [{id: "10", sections: [{id: "1", children: ["10", "11"]}, {id: "2", children: ["12"]}], childrenWithoutSections: ["1", "2"]}, {id: "11", sections: [{id: "3", children: ["13", "14"]}, {id: "4", children: ["15"]}], childrenWithoutSections: ["3", "4"]}] console.log (extract (groups))

 .as-console-wrapper {max-height: 100%;important: top: 0}

 <script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.27.2/ramda.min.js"></script> <script> const {chain, lift, concat, pipe, prop, pluck, flatten} = R </script>

Answer 2

Another option is to use R.juxt to get children from the sections , and the childrenWithoutSections and then flattening the results. By chaining the results we get the array of values.

 const {chain, pipe, juxt, prop, pluck, flatten } = R const fn = chain(pipe( juxt([ pipe(prop('sections'), pluck('children')), prop('childrenWithoutSections') ]), flatten, )) const groups = [{id: "10", sections: [{id: "1", children: ["10", "11"]}, {id: "2", children: ["12"]}], childrenWithoutSections: ["1", "2"]}, {id: "11", sections: [{id: "3", children: ["13", "14"]}, {id: "4", children: ["15"]}], childrenWithoutSections: ["3", "4"]}] const result = fn(groups) console.log(result)

 .as-console-wrapper {max-height: 100%;important: top: 0}

 <script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.27.2/ramda.min.js"></script>