fix(edit): 清空字段能真正提交(undefined→null,避免 JSON 丢键)

清空 relation/select 时 el-* 常 emit undefined，进 submitData 后 JSON.stringify 丢键 →
后端收不到、看似'提交无效'。修:
- handleSave 编辑 diff 把值归一成 null(??null)，清空 → null → 提交 → 后端置空
- FieldRelation 清空归一成 null(单)/[](多)，避免 ObjectId 存 '' cast 报错

package.json

@@ -1,6 +1,6 @@
 {
     "name": "shrimp-admin",
-    "version": "0.3.6",
+    "version": "0.3.8",
     "private": true,
     "description": "Shrimp 框架前端 — 消费 ShrimpServer + ShrimpTable 契约的经典 Vue3 + Element Plus 实现",
     "main": "src/index.ts",

src/components/ShrimpTable.vue

@@ -334,8 +334,10 @@ async function handleSave() {
             formFields.value.forEach(field => {
                 if (field.editable === 'readonly') return
                 if (field.editable === 'addOnly') return
-                const newValue = formData.value[field.key]
-                const oldValue = originalData.value[field.key]
+                // 清空字段值为 undefined 时，JSON.stringify 会丢键 → 后端收不到、看似"提交无效"。
+                // 归一成 null：既保证清空能提交(后端置空)，又让"两边都空"不误判为有改动。
+                const newValue = formData.value[field.key] ?? null
+                const oldValue = originalData.value[field.key] ?? null
                 if (newValue === oldValue) return
                 submitData[field.key] = newValue
             })

src/components/fields/FieldDate.vue

@@ -42,7 +42,7 @@
         style="width: 100%"
     />
     <el-date-picker v-else :model-value="modelValue" @update:model-value="$emit('update:modelValue', $event)" :disabled="disabled"
-        type="datetime" style="width: 100%" />
+        type="datetime" :clearable="!field.required" style="width: 100%" />
 </template>
 
 <script lang="ts" setup>

src/components/fields/FieldRelation.vue

@@ -18,7 +18,7 @@
     >
         <el-option v-for="opt in options" :key="opt.value" :label="opt.label" :value="opt.value" />
     </el-select>
-    <el-select v-else :model-value="stringValue" @update:model-value="$emit('update:modelValue', $event)" :disabled="disabled" :multiple="field.multiple" filterable remote :remote-method="onSearch" :loading="loading" style="width: 100%">
+    <el-select v-else :model-value="stringValue" @update:model-value="onEdit" :disabled="disabled" :multiple="field.multiple" :clearable="!field.required" filterable remote :remote-method="onSearch" :loading="loading" style="width: 100%">
         <el-option v-for="opt in options" :key="opt.value" :label="opt.label" :value="opt.value" />
     </el-select>
 </template>
@@ -35,10 +35,16 @@ const props = defineProps<{
     disabled?: boolean
 }>()
 
-defineEmits<{
+const emit = defineEmits<{
     'update:modelValue': [value: any]
 }>()
 
+// 编辑态清空：el-select 单选清空发 '' 或 undefined，relation 是 ObjectId、且 undefined 会被
+// JSON.stringify 丢键 → 都归一成 null(取消关联)。多选清空是 []，原样。
+function onEdit(v: any) {
+    emit('update:modelValue', v === '' || v == null ? (props.field.multiple ? [] : null) : v)
+}
+
 const options = ref<{ label: string; value: string }[]>([])
 const loading = ref(false)
 

src/components/fields/FieldSelect.vue

@@ -21,6 +21,7 @@
         @update:model-value="$emit('update:modelValue', $event)"
         :disabled="disabled"
         :multiple="field.multiple"
+        :clearable="!field.required"
         style="width: 100%"
     >
         <el-option v-for="opt in resolvedOptions" :key="opt.value" :label="vueAdmin.t(opt.label)" :value="opt.value" />

src/components/fields/FieldString.vue

@@ -9,7 +9,7 @@
         </el-tag>
         <el-input v-model="inputValue" @keyup.enter="addTag" @blur="addTag" :placeholder="$t('base.pressEnter')" />
     </div>
-    <el-input v-else :model-value="modelValue" @update:model-value="$emit('update:modelValue', $event)" :disabled="disabled" clearable />
+    <el-input v-else :model-value="modelValue" @update:model-value="$emit('update:modelValue', $event)" :disabled="disabled" :clearable="!field.required" />
 </template>
 
 <script lang="ts" setup>

src/components/fields/FieldTextarea.vue

@@ -19,7 +19,7 @@
         :model-value="modelValue"
         @update:model-value="$emit('update:modelValue', $event)"
         :disabled="disabled"
-        clearable
+        :clearable="!field.required"
     />
 </template>