el-select控制单选还是多选

 <el-form :inline="true" :model="form" class="demo-form-inline"><el-form-item><el-select v-model="form.properties_id" placeholder="请选择样品性质" clearable :multiple="multiple_properties"  @change="getData()" @focus="focus_properties()" style="width: 300px"><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" placeholder="请选择品名" clearable :multiple="multiple_place" @change="getData()" @focus="focus_place()" style="width: 300px"><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>

  form: {properties_id : [],place_id      : [],},multiple_properties: true,multiple_place: true,

 //properties 获得焦点focus_properties(){var that = thisthat.form.properties_id = [];if(that.form.place_id.length > 1){that.multiple_place = true;that.multiple_properties = false;}else{that.multiple_properties = true;//that.multiple_place = true;}},//place 获得焦点focus_place(){var that = thisthat.form.place_id = [];if(that.form.properties_id.length > 1){that.multiple_place = false;that.multiple_properties = true;}else{//that.multiple_properties = true;that.multiple_place = true;}},getData(){var that = this//样品性质var properties_id = [];var properties_id_len = that.form.properties_id.length;if(properties_id_len == undefined){//此时会变成字符串var str = that.form.properties_idproperties_id= JSON.parse("[" + str + "]");//变成数组形式}else{properties_id = that.form.properties_id;}//品名var place_id = [];var place_id_len = that.form.place_id.length;if(place_id_len == undefined){//此时会变成字符串var str = that.form.place_idplace_id= JSON.parse("[" + str + "]");//变成数组形式}else{place_id = that.form.place_id;}if(properties_id.length == 0){properties_id = null;}if(place_id.length == 0){place_id = null;}$.ajax({url: "/admin/report/getDevetimeData",type: "GET",data : {properties_id : properties_id,place_id      : place_id,},dataType:'json',success: function (res) {if (res.code == 100) {that.data = res.data;}}});},