shadcn-ui 增加 multi-select

前言

multi-select 是一個很常見的組件，但 shadcn-ui 並沒有提供
原本想說自己來刻一個吧，再查一下資料時，發現已經有人做好了！
試了一下發現完全符合我期望的功能，就不在造輪子直接用了 XD

demo: Fancy Multi Select

完全使用 shadcn-ui 的組件組裝而成，唯一就是多了 cmdk 套件

安裝方式

1. npm i cmdk
2. 將下列程式碼(僅留存備份)拷貝到@/component/ui/multi-select.tsx。或至原專案拷貝原始碼

"use client";

import * as React from "react";
import { X } from "lucide-react";

import { Badge } from "@/components/ui/badge";
import {
  Command,
  CommandGroup,
  CommandItem,
} from "@/components/ui/command";
import { Command as CommandPrimitive } from "cmdk";

type Framework = Record<"value" | "label", string>;

const FRAMEWORKS = [
  {
    value: "next.js",
    label: "Next.js",
  },
  {
    value: "sveltekit",
    label: "SvelteKit",
  },
  {
    value: "nuxt.js",
    label: "Nuxt.js",
  },
  {
    value: "remix",
    label: "Remix",
  },
  {
    value: "astro",
    label: "Astro",
  },
  {
    value: "wordpress",
    label: "WordPress",
  },
  {
    value: "express.js",
    label: "Express.js",
  },
  {
    value: "nest.js",
    label: "Nest.js",
  }
] satisfies Framework[];

export function FancyMultiSelect() {
  const inputRef = React.useRef<HTMLInputElement>(null);
  const [open, setOpen] = React.useState(false);
  const [selected, setSelected] = React.useState<Framework[]>([FRAMEWORKS[4]]);
  const [inputValue, setInputValue] = React.useState("");

  const handleUnselect = React.useCallback((framework: Framework) => {
    setSelected(prev => prev.filter(s => s.value !== framework.value));
  }, []);

  const handleKeyDown = React.useCallback((e: React.KeyboardEvent<HTMLDivElement>) => {
    const input = inputRef.current
    if (input) {
      if (e.key === "Delete" || e.key === "Backspace") {
        if (input.value === "") {
          setSelected(prev => {
            const newSelected = [...prev];
            newSelected.pop();
            return newSelected;
          })
        }
      }
      // This is not a default behaviour of the <input /> field
      if (e.key === "Escape") {
        input.blur();
      }
    }
  }, []);

  const selectables = FRAMEWORKS.filter(framework => !selected.includes(framework));

  return (
    <Command onKeyDown={handleKeyDown} className="overflow-visible bg-transparent">
      <div
        className="group border border-input px-3 py-2 text-sm ring-offset-background rounded-md focus-within:ring-2 focus-within:ring-ring focus-within:ring-offset-2"
      >
        <div className="flex gap-1 flex-wrap">
          {selected.map((framework) => {
            return (
              <Badge key={framework.value} variant="secondary">
                {framework.label}
                <button
                  className="ml-1 ring-offset-background rounded-full outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2"
                  onKeyDown={(e) => {
                    if (e.key === "Enter") {
                      handleUnselect(framework);
                    }
                  }}
                  onMouseDown={(e) => {
                    e.preventDefault();
                    e.stopPropagation();
                  }}
                  onClick={() => handleUnselect(framework)}
                >
                  <X className="h-3 w-3 text-muted-foreground hover:text-foreground" />
                </button>
              </Badge>
            )
          })}
          {/* Avoid having the "Search" Icon */}
          <CommandPrimitive.Input
            ref={inputRef}
            value={inputValue}
            onValueChange={setInputValue}
            onBlur={() => setOpen(false)}
            onFocus={() => setOpen(true)}
            placeholder="Select frameworks..."
            className="ml-2 bg-transparent outline-none placeholder:text-muted-foreground flex-1"
          />
        </div>
      </div>
      <div className="relative mt-2">
        {open && selectables.length > 0 ?
          <div className="absolute w-full z-10 top-0 rounded-md border bg-popover text-popover-foreground shadow-md outline-none animate-in">
            <CommandGroup className="h-full overflow-auto">
              {selectables.map((framework) => {
                return (
                  <CommandItem
                    key={framework.value}
                    onMouseDown={(e) => {
                      e.preventDefault();
                      e.stopPropagation();
                    }}
                    onSelect={(value) => {
                      setInputValue("")
                      setSelected(prev => [...prev, framework])
                    }}
                    className={"cursor-pointer"}
                  >
                    {framework.label}
                  </CommandItem>
                );
              })}
            </CommandGroup>
          </div>
          : null}
      </div>
    </Command >
  )
}

參考資料

GitHub issue / Multi select ?
Fancy Multi Select