<el-select
  v-model="userId"
  filterable
  :filter-method="userFilter"
  clearable>
  <el-option
    v-for="item in userList"
    :key="item.userId"
    :label="item.username"
    :value="item.userId"
  ></el-option>
</el-select>

userFilter(query = '') {
  let arr = this.allUserList.filter((item) => {
    return item.username.includes(query) || item.userId.includes(query)
  })
  if (arr.length > 50) {
    this.userList = arr.slice(0, 50)
  } else {
    this.userList = arr
  }
},
getUserWhiteList() {
  HttpRequest.post("/api/admin/community/getUserWhiteList").then(
    response => {
      this.allUserList = response.data.list;
      this.userFilter()
    }
  );
},

<template>
    <el-select
        class="yt-select"
        v-model="currValue"
        filterable
        v-bind="$attrs"
        :filter-method="userFilter"
        :disabled="disabled"
        :clearable="clearable"
        @change="change"
    >
        <el-option
            v-for="option in renderOption"
            :key="option.value"
            :value="option.value"
            :label="option.label"
        >{{ option.label }}</el-option>
    </el-select>
</template>

<script>

export default {
    name: 'easy-select',
    props: {
        value: {
            type: [String, Number],
            default: ''
        },
        max: {
            type: Number,
            default: 30
        },
        disabled: {
            type: Boolean,
            default: false
        },
        clearable: {
            type: Boolean,
            default: true
        },
        options: {
            type: Array,
            default: () => []
        }
    },
    data () {
        return {
            renderOption: []
        }
    },
    computed: {
        currValue: {
            get () {
                return this.value || ''
            },
            set (value) {
                this.$emit('input', value)
            }
        }
    },
    watch: {
        value () {
            this.addValueOptions()
        },
        options: {
            handler (V) {
                this.init()
            },
            deep: true
        }
    },
    created () {
        this.init()
    },
    methods: {
        async init () {
            this.userFilter()
            this.addValueOptions()
        },
        addValueOptions () {
            if (this.currValue) {
                let target = this.options.find((item) => { // 從大option中找到當前條
                    return item.value === this.currValue
                })
                if (target) { // 將當前條與小option比對，沒有則加入
                    if (this.renderOption.every(item => item.value !== target.value)) {
                        this.renderOption.unshift(target)
                    }
                }
            }
        },
        addFilterOptions (label) {
         // 每次查找輸入時，若有精確匹配的條目，保證該條目一定在renderOption內
            let target = this.options.find((item) => { // 從大option中找到當前條
                return item.label === label
            })
            if (target) { // 將當前條與小option比對，沒有則加入
                if (this.renderOption.every(item => item.label !== target.label)) {
                    this.renderOption.unshift(target)
                }
            }
        },
        userFilter (query = '') {
            let arr = this.options.filter((item) => {
                return item.label.includes(query) || item.value.includes(query)
            })
            if (arr.length > this.max) {
                this.renderOption = arr.slice(0, this.max)
                this.addFilterOptions(query)
            } else {
                this.renderOption = arr
            }
        },
        change (value) {
            this.$emit('change', value)
            if (!value) { // 單選清空-optons初始化下
                this.userFilter()
            }
        }
    }
}
</script>