fix；修改列表导出字段设置逻辑

src/business/platform/data/templatebuilder/right-aside/components/export-column.vue

@@ -168,10 +168,10 @@ export default {
         // 当未设置导出字段或已设置导出字段但是字段数量与数据集字段不等时（说明表中有新增字段），重新获取导出字段
         if (this.$utils.isEmpty(val.export_columns)) {
           this.exportColumns.fields = this.initFormData(this.datasets)
-        } else if (val.export_columns.fields && (val.export_columns.fields.length !== arr.length)) {
+        } else if (val.export_columns.fields.length !== 0 && (val.export_columns.fields.length !== arr.length)) {
           // 导出字段跟当前字段数量的差异
-          const diff = arr.filter(v => this.exportColumns.fields.every(val => val.name !== v.name))
-          this.exportColumns.fields.concat(this.initFormData(diff))
+          const diff = arr.filter(v => val.export_columns.fields.every(val => val.name !== v.name))
+          this.exportColumns.fields = JSON.parse(JSON.stringify(val.export_columns.fields.concat(this.initFormData(diff))))
         } else {
           this.exportColumns = val.export_columns
         }