IntegrityError：（1062， 「重複條目 '1830327-1792993' 關鍵 'some_instance_A_id'」），但沒有UNIQUE約束

Question

我很少得到這樣的異常增加時，模型實例many2many領域，即：

some_instance_A.my_m2m.add(some_instance_B)). 

它說99/100倍。看起來很怪，是破折號標誌 - 作爲主鍵是整數..

型號字段定義是這樣的：

my_m2m = ManyToManyField(B) 

所以這是最簡單的M2M定義可能

完全回溯（與小編輯保護隱私:)）：

File "*******", line 278, in process_request 
    some_instance_A.my_m2m.add(some_instance_B) 
File "/var/lib/python-support/python2.5/django/db/models/fields/related.py", line 490, in add 
    self._add_items(self.source_field_name, self.target_field_name, *objs) 
File "/var/lib/python-support/python2.5/django/db/models/fields/related.py", line 574, in _add_items 
    '%s_id' % target_field_name: obj_id, 
File "/var/lib/python-support/python2.5/django/db/models/query.py", line 352, in create 
    obj.save(force_insert=True, using=self.db) 
File "/var/lib/python-support/python2.5/django/db/models/base.py", line 435, in save 
self.save_base(using=using, force_insert=force_insert, force_update=force_update) 
File "/var/lib/python-support/python2.5/django/db/models/base.py", line 528, in save_base 
result = manager._insert(values, return_id=update_pk, using=using) 
File "/var/lib/python-support/python2.5/django/db/models/manager.py", line 195, in _insert 
return insert_query(self.model, values, **kwargs) 
File "/var/lib/python-support/python2.5/django/db/models/query.py", line 1479, in insert_query 
return query.get_compiler(using=using).execute_sql(return_id) 
File "/var/lib/python-support/python2.5/django/db/models/sql/compiler.py", line 783, in execute_sql 
cursor = super(SQLInsertCompiler, self).execute_sql(None) 
File "/var/lib/python-support/python2.5/django/db/models/sql/compiler.py", line 727, in execute_sql 
cursor.execute(sql, params) 
File "/var/lib/python-support/python2.5/django/db/backends/mysql/base.py", line 86, in execute 
return self.cursor.execute(query, args) 
File "/var/lib/python-support/python2.5/MySQLdb/cursors.py", line 166, in execute 
self.errorhandler(self, exc, value) 
File "/var/lib/python-support/python2.5/MySQLdb/connections.py", line 35, in defaulterrorhandler 
raise errorclass, errorvalue 
IntegrityError: (1062, "Duplicate entry '1830327-1792993' for key 'some_instance_A_id'") 

Answer 1

你可以發佈產生這種結果的代碼片段嗎？

至少在Postgres上，如果您嘗試在事務中保存兩次實例，就會發生這種情況。