Ramdajs：如何根据对象属性过滤列表？

Question

 const abby = {name: 'Abby', attributes: {age: 7, hair: 'blond'}}; const fred = {name: 'Fred', attributes: {age: 12, hair: 'brown'}}; const rusty = {name: 'Rusty', attributes: {age: 10, hair: 'brown'}}; const alois = {name: 'Alois', attributes: {age: 15, disposition: 'surly'}}; const kids = [abby, fred, rusty, alois]; console.log = function(text) { $('#console').append($('<div>').text(text)); }; // current code console.log(R.filter(R.compose(R.propEq('hair', 'blond'), R.props('attributes')))(kids));

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script> <div id="console"></div>

I want to get the objects whose hair is 'blond'. I tried using compose but unluckily it doesn't work. I am still new with ramda.

Answer 1

Your initial attempt is almost correct; R.props('attributes') should have been R.prop('attributes') instead:

R.filter(R.compose(R.propEq('hair', 'blond'), R.prop('attributes')))(kids)

However you may find it easier to use pathSatisfies if you need to assert against a nested property:

Returns true if the specified object property at given path satisfies the given predicate; false otherwise.

 const {filter, pathSatisfies, equals} = R; const abby = {name: 'Abby', attributes: {age: 7, hair: 'blond'}}; const fred = {name: 'Fred', attributes: {age: 12, hair: 'brown'}}; const rusty = {name: 'Rusty', attributes: {age: 10, hair: 'brown'}}; const alois = {name: 'Alois', attributes: {age: 15, disposition: 'surly'}}; const kids = [abby, fred, rusty, alois]; console.log( filter(pathSatisfies(equals('blond'), ['attributes', 'hair']), kids) )

 <script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>

References

1. props
2. prop
3. pathSatisfies

Answer 2

it is year 2020, I guess use pathEQ is much simple

const R = require("ramda");
let out = "";
const abby = { name: "Abby", attributes: { age: 7, hair: "blond" } };
const fred = { name: "Fred", attributes: { age: 12, hair: "brown" } };
const rusty = { name: "Rusty", attributes: { age: 10, hair: "brown" } };
const alois = { name: "Alois", attributes: { age: 15, disposition: "surly" } };
const kids = [abby, fred, rusty, alois];
out = R.filter(R.pathEq(["attributes", "hair"], "blond"))(kids);