Ramda - how to get nested array values
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?
Solution 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>Solution 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>