cascading-deletes

问题 I have a Foreign Key from one model into another model in a differente database (I know I shouldn't do it but if I take care properly of Referential Integrity it shouldn't be a problem). The thing is that everything works fine...all the system does (relationships on any direction, the router takes care of it) but when I try to delete the referenced model (which doesn't have the foreign key attribute)...Django still wants to go throught the relationship to check if the relationship is empty,

问题 I have a Foreign Key from one model into another model in a differente database (I know I shouldn't do it but if I take care properly of Referential Integrity it shouldn't be a problem). The thing is that everything works fine...all the system does (relationships on any direction, the router takes care of it) but when I try to delete the referenced model (which doesn't have the foreign key attribute)...Django still wants to go throught the relationship to check if the relationship is empty,

问题 I have a Foreign Key from one model into another model in a differente database (I know I shouldn't do it but if I take care properly of Referential Integrity it shouldn't be a problem). The thing is that everything works fine...all the system does (relationships on any direction, the router takes care of it) but when I try to delete the referenced model (which doesn't have the foreign key attribute)...Django still wants to go throught the relationship to check if the relationship is empty,

问题 I have a Foreign Key from one model into another model in a differente database (I know I shouldn't do it but if I take care properly of Referential Integrity it shouldn't be a problem). The thing is that everything works fine...all the system does (relationships on any direction, the router takes care of it) but when I try to delete the referenced model (which doesn't have the foreign key attribute)...Django still wants to go throught the relationship to check if the relationship is empty,

问题 In my application post_delete signals being recorded in a specific model and when it was removed. class A(models.Model): ... class B(models.Model): a = models.ForeignKey('A') class C(models.Model): b = models.ForeignKey('B') def log_delete(sender, instance, **kwargs): logging post_delete.connect(log_delete, sender = A) post_delete.connect(log_delete, sender = C) When you delete an instance of A cascade delete occurs removing B and C instances. How can I disable signal for child instances on

问题 There are many related questions but unfortunately I can't find working solution I have Laravel model and when this model is deleted I want to delete some related models run custom SQL query when deleting model My Laravel's model class looks like (as you can see models can have different relation types) class ModelA extends Model { public functions modelsB() { return $this->hasMany(ModelB:class); } public functions modelsC() { return $this->belongsToMany(ModelC:class); } // other related

问题 Is it possible to predict the operations that follow a DELETE CASCADE automatically? In my software I would like to give the user a warning with details about the data that would be deleted then. 回答1: You can make a copy of the database and put triggers on the after delete DELIMITER $$ CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW BEGIN INSERT INTO log VALUES (null /*autoinc id*/ , 'table1' /*tablename*/ , old.id /*tableid*/ , concat_ws(',',old.field1,old.field2 /*CSV's of

问题 Is it possible to predict the operations that follow a DELETE CASCADE automatically? In my software I would like to give the user a warning with details about the data that would be deleted then. 回答1: You can make a copy of the database and put triggers on the after delete DELIMITER $$ CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW BEGIN INSERT INTO log VALUES (null /*autoinc id*/ , 'table1' /*tablename*/ , old.id /*tableid*/ , concat_ws(',',old.field1,old.field2 /*CSV's of

问题 Is it possible to predict the operations that follow a DELETE CASCADE automatically? In my software I would like to give the user a warning with details about the data that would be deleted then. 回答1: You can make a copy of the database and put triggers on the after delete DELIMITER $$ CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW BEGIN INSERT INTO log VALUES (null /*autoinc id*/ , 'table1' /*tablename*/ , old.id /*tableid*/ , concat_ws(',',old.field1,old.field2 /*CSV's of

问题 Is it possible to predict the operations that follow a DELETE CASCADE automatically? In my software I would like to give the user a warning with details about the data that would be deleted then. 回答1: You can make a copy of the database and put triggers on the after delete DELIMITER $$ CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW BEGIN INSERT INTO log VALUES (null /*autoinc id*/ , 'table1' /*tablename*/ , old.id /*tableid*/ , concat_ws(',',old.field1,old.field2 /*CSV's of