Lodash 等价于 C# LINQ GroupBy 和 TypeScript 中的 Select

Question

I'm trying to find a way to do the equivalent of .GroupBy(key => key.IdShopItem).Select(item => item.Single()); in typescript.

I've tried this LinQ for TypeScript https://github.com/kutyel/linq.ts but it seems there's a bug and also it does not support this so far.

Also I've tried with lodash https://lodash.com/docs/4.17.10#groupBy , but I had no success.

How can I achieve this please? Already spend a couple of hours on this...

Answer 1

Disclaimer: I wrote this library

You could use the javascript loq library to achieve this. Here's a snippet to get you on your way:

 var list = [ {name:"dog",type:"animal"}, {name:"cat",type:"animal"}, {name:"snake",type:"animal"}, {name:"table",type:"furniture"}, {name:"chair",type:"furniture"}, ]; var filtered = loq(list).distinctBy(item => item.type); console.log(filtered.toArray());

 <script src="https://cdn.rawgit.com/biggyspender/loq/67db7014/lib/loq.min.js"></script>

...or with requirejs

 requirejs.config({ paths: { loq: 'https://cdn.rawgit.com/biggyspender/loq/67db7014/lib/loq.min' } }); require(['loq'], function(loq){ var list = [ {name:"dog",type:"animal"}, {name:"cat",type:"animal"}, {name:"snake",type:"animal"}, {name:"table",type:"furniture"}, {name:"chair",type:"furniture"}, ]; var filtered = loq(list).distinctBy(item => item.type); console.log(filtered.toArray()); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/require.js/2.1.14/require.js"></script>

It's a relatively complete reimplementation of LINQ-to-objects on iterables (objects that implement Symbol.iterator ) with a few extra goodies (such as distinctBy ). Take a look at the tests to see other uses.