fix(教师表单): 允许作业频率和目标数量设置为0并转换为空值

将表单中作业频率和目标数量的最小值从1改为0，并在提交时处理0值转换为空值

@@ -2,7 +2,7 @@
  * @Author: hookehuyr hookehuyr@gmail.com
  * @Date: 2025-01-20 10:00:00
  * @LastEditors: hookehuyr hookehuyr@gmail.com
- * @LastEditTime: 2025-10-14 11:32:42
+ * @LastEditTime: 2025-10-14 13:48:57
  * @FilePath: /mlaj/src/views/teacher/formPage.vue
  * @Description: 教师作业新增表单页面
 -->
@@ -77,7 +77,7 @@
                     <div class="target-count-container">
                       <van-stepper
                         v-model="formData.frequency"
-                        min="1"
+                        min="0"
                         max="100"
                         integer
                         button-size="24px"
@@ -95,7 +95,7 @@
                     <div class="target-count-container">
                       <van-stepper
                         v-model="formData.target_number"
-                        min="1"
+                        min="0"
                         max="100"
                         integer
                         button-size="24px"
@@ -905,6 +905,9 @@ const handleSubmit = async (values) => {
       // 格式化日期为YYYY-MM-DD格式
       begin_date: formatDateTime(formData.value.start_time),
       end_date: formatDateTime(formData.value.end_time),
+      // 处理每周期提交数量和目标总数，当值为0时转换为空值
+      frequency: formData.value.frequency === 0 ? null : formData.value.frequency,
+      target_number: formData.value.target_number === 0 ? null : formData.value.target_number,
       // 添加课程章节选择数据
       schedule: selectedChapters.value.map(chapter => ({
         id: chapter.id,