fix: form prop rules不生效 (#208)

Author: yolofit

docs/rules-plus.md

@@ -0,0 +1,41 @@
+```vue
+<template>
+   <el-form-renderer
+      label-width="100px"
+      :content="content"
+      ref="form"
+      :rules="rules"
+    >
+    </el-form-renderer>
+</template>
+
+<script>
+export default {
+  
+  data() {
+    const rules = [
+      { required: true, message: '请输入活动名称', trigger: 'change' },
+      { min: 3, max: 5, message: '长度在 3 到 5 个字符', trigger: 'change' }
+    ];
+    return {
+      rules: {
+        name: [...rules],
+      },
+      content: [
+        {
+          type: "input",
+          id: "name",
+          label: "name",
+        },
+        {
+          type: "input",
+          id: "desc",
+          label: "desc",
+          rules: [...rules],
+        },
+      ],
+    };
+  },
+}
+</script>
+```

src/components/render-form-item.vue

@@ -3,7 +3,7 @@
     v-if="_show"
     :prop="prop"
     :label="typeof data.label === 'string' ? data.label : ''"
-    :rules="!readonly && Array.isArray(data.rules) ? data.rules : []"
+    :rules="!readonly && Array.isArray(data.rules) ? data.rules : undefined"
     v-bind="data.attrs"
     class="render-form-item"
   >