fix: 修复v-for和v-if在同一元素导致内容不渲染的问题

src/pages/category/index.vue

@@ -70,7 +70,7 @@
             <input class="input attr-unit" v-model="attr.unit" placeholder="单位" />
             <text class="attr-delete" @click="removeAttr(index)">×</text>
           </view>
-          <view v-for="(attr, index) in attributes" :key="'formula-'+index" class="formula-item" v-if="attr.attrType === 'formula'">
+          <view v-for="(attr, index) in formulaAttrs" :key="'formula-'+index" class="formula-item">
             <text class="formula-label">公式：</text>
             <input class="input formula-input" v-model="attr.formula" placeholder="例如: length * width" />
           </view>
@@ -107,6 +107,11 @@ export default {
       attributes: []
     }
   },
+  computed: {
+    formulaAttrs() {
+      return this.attributes.filter(a => a.attrType === 'formula')
+    }
+  },
   onLoad() {
     this.loadCategories()
   },