修复viewparams为字符串时处理逻辑异常问题

@VIEW/@MACRO/VIEW_HEADER-BASE.vue.ftl

@@ -175,11 +175,11 @@ export default class ${srfclassname('${view.name}')}Base extends Vue {
     @Watch('viewparam',{immediate: true, deep: true})
     onParamData(newVal: any, oldVal: any) {
         if(newVal){
-            for(let key in this.viewparams){
-                delete this.viewparams[key];
-            }
+            this.viewparams = {};
             if(typeof this.viewparams == 'string') {
                 Object.assign(this.viewparams, JSON.parse(this.viewparam));
+            }else{
+                this.viewparams = Util.deepCopy(this.viewparam);
             }
             <#if watch_viewparam_block??>${watch_viewparam_block}</#if>
         }