el-select控制单选还是多选

multiple表示多选，:multiple-limit="1" 限制多选的条数为1，2就是选两个，依此类推。为0 就是不限制选几个
使用 allow-create 属性即可通过在输入框中输入文字来创建新的条目。注意此时 filterable 必须为真。

  <el-form :inline="true" :model="form" class="demo-form-inline">
      <el-select v-model="form.properties_id" style="width: 300px" placeholder="请选择样品性质" filterable clearable multiple @change="getData()" :multiple-limit="limit_properties">
        <el-option v-for="item in sample_properties" :label="item.label" :value="item.value" :key="item.value"></el-option>
      </el-select>
    </el-form-item>
    <el-form-item>
      <el-select v-model="form.place_id" style="width: 300px" placeholder="请选择品名" filterable clearable multiple @change="getData()" :multiple-limit="limit_place">
        <el-option v-for="item in place_data" :label="item.label" :value="item.value" :key="item.value"></el-option>
      </el-select>
    </el-form-item>
  </el-form>

    data() {
      return {
        sample_properties:@json($sample_properties),
        place_data:@json($place_data),
        form: {
          properties_id : [],
          place_id      : [],
        },
        limit_properties : 0,
        limit_place : 0,
      }
    },

   methods: {
     getData(){
        var that = this
        if(that.form.properties_id.length>1 && that.form.place_id.length<=1)						
        {
          that.limit_properties= 0 //没限制
          that.limit_place= 1 //限制1条
        }
        if(that.form.place_id.length>1 && that.form.properties_id.length<=1)
        {
          that.limit_properties= 1
          that.limit_place= 0
        }
       if(that.form.place_id.length==1 && that.form.properties_id.length==1)
       {
          that.limit_properties= 0
          that.limit_place= 0
       }
       //......
     },
   },