打印入仓单必须选择品名，未选择品名不可点击确认打印

http://zentao.jdshangmen.com/bug-view-2028.html

src/views/ecw/order/components/PrintWarehouseReceipt.vue

@@ -64,7 +64,7 @@
                 </p>
             </div>
             <p class="subs" style="text-align:center">
-                <el-button v-if="!preview" type="primary" @click="preview=true">{{$t('去打印')}}</el-button>
+                <el-button v-if="!preview" type="primary" @click="toPrint">{{$t('去打印')}}</el-button>
                 <el-button v-if="preview" type="primary" @click="print">{{$t('确定打印')}}</el-button>
             </p>
         </div>
@@ -151,6 +151,13 @@ export default {
             this.show = false
             this.$emit('close');
         },
+        toPrint(){
+          if (this.items.findIndex(e => e.checked) !== -1){
+            this.preview = true
+          } else {
+            this.$message.warning(this.$t('请选择品名'))
+          }
+        },
         print(){
             this.$nextTick(() => {
                 lodop().then(LODOP => {