fix: 修改opl level字段默认为空字符

apps/opm/migrations/0011_alter_opl_level.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2023-04-12 06:08
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('opm', '0010_alter_opl_ticket'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='opl',
+            name='level',
+            field=models.CharField(default='', help_text='特技/三级/二级/主干道/次干道', max_length=20, verbose_name='作业级别'),
+        ),
+    ]

apps/opm/models.py

@@ -74,7 +74,7 @@ class Opl(CommonBDModel):
     number = models.CharField('作业许可编号', max_length=20, null=True, blank=True)
     work_scope = models.CharField('作业范围', max_length=200, null=True, blank=True)
     level = models.CharField('作业级别', max_length=20,
-                             help_text='特技/三级/二级/主干道/次干道', null=True, blank=True)
+                             help_text='特技/三级/二级/主干道/次干道', default='')
     cate = models.ForeignKey(OplCate, verbose_name='作业许可种类',
                              on_delete=models.CASCADE)
     start_time = models.DateTimeField('作业开始时间', null=True, blank=True)