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The problem with this is that running the stored procedure didn't update the EF cache, so even though the old entities were gone from the database, EF was still holding onto them, and when it came time to save, we got errors to the effect of: duplicates This article will discuss alternative methods for performing cascading deletes using LINQ to SQL. Why is this not happening? With large files, it will be blocked See Cascade Delete for more details on how cascade delete behaviors work, how they can be configured explicitly and how they are selected by convention. 1) Shows how DELETE cascade works -- Parent table CREATE TABLE supplier ( supplier_id numeric(10) not null, supplier_name varchar2(50), contact_name varchar2(50), CONSTRAINT supplier_pk PRIMARY KEY (supplier_id) ); -- children table with foreign key CREATE TABLE products ( product_id … We're trying to get cascading to work in EF in the hopes of at least making it a bit faster. the database is locked, which means no other process can access the database until step 4 above is done. Be sure to read sections above before coming here. Name the project Notes and, to speed things up, check Use Core Dataat the bottom. The department will not be set to null. There is no difference in deleting an entity in the connected and disconnected scenario in EF Core. Hopefully that works. Severing a relationship is not valid here since the dependents/children are not loaded. The EF Core in-memory database does not currently support cascade deletes in the database. Despite what NO ACTION may imply, both of these options cause referential constraints to be enforced. If the principal/parent entity is deleted, then the foreign key values of the dependents/children will no longer match the primary or alternate key of any principal/parent. For example: Notice that there is no Include for posts, so they are not loaded. it works well. I'm not too familiar with how The only reason this didn't seem to be an issue before was that between the time when the delete stored procedure was run and the time when it began to parse the file, a new context was injected into the file parsing function. entities manually is exceptionally slow. For example, consider the following model: This model has three relationships, all required and therefore configured to cascade delete by convention: This is all reasonable (if a bit draconian in blog management policies!) When deleting a blog, all posts are cascade deleted. By convention, this relationship is configured as a required, since the Post.BlogId foreign key property is non-nullable. Consider an example of Customer Registration. but attempting to create a SQL Server database with these cascades configured results in the following exception: Microsoft.Data.SqlClient.SqlException (0x80131904): Introducing FOREIGN KEY constraint 'FK_Posts_Person_AuthorId' on table 'Posts' may cause cycles or multiple cascade paths. EF will delete a child record(s) (database rows) automatically when its parent is explicitly deleted via the DbContext. I don't think you will see a performance difference between trigger and using cascade. record in EF. The OnDelete method takes a DeleteBehavior enum as a parameter:. without the old entities after the stored procedure had run). Delete rules are activate when an object of the entity with the delete rule is deleted. The following example shows how to setup and cascade works when deleting record from parent table. Add ON DELETE CASCADE To Foreign Key Constraint. See the next section for more information on configuring cascading nulls. "Delete" Example. Cascading doesn't work because for all the objects I'd like to cascade upon deletion, there will be multiple or cyclical cascade paths which is not allowed (for some bizarre reason) in SQL Server. When I was trying to manually delete all drawings, my code looked like this: This worked (no errors) but it's extremely slow. Conclusion. If the foreign-key does seconds). My guess is that this In any case, we decided to try a different approach after that: deleting from the EF cache: Here, we are deleting from the EF cache first, then parsing the file, then saving. The following table shows the result of each OnDelete value on the foreign key constraint created by EF Core migrations or EnsureCreated. I figured that if I let EF handle all the work of deleting entities (starting with manual deletions on just a few at the topmost level of the hierarchy), then it's bound Cascade - dependents should be deleted; Restrict - dependents are unaffected; SetNull - the foreign key values in dependent rows should update to NULL This can happen because the principal/parent is deleted, or it can happen when the principal/parent still exists but the dependent/child is no longer associated with it. However, according to the EFCore docs, a Required relationship will be set to Cascade delete functionality. Looks like I'm stuck deleting each and every entity manually in code. Delete behaviors are defined in the DeleteBehavior enumerator type and can be passed to the OnDeletefluent API to control whether the deletion of a principal/parent entity or the severing of the relationship to dependent/child entities should have a side effect on the dependent/child entities. IOW, it was trying to save both the new entities AND the old ones. 2) Delete stored procedure runs to delete old data. Th… detected (old and new entities conflict). Well, neither ON DELETE CASCADE nor INSTEAD OF DELETE work. The fixup of relationships like this has been the default behavior of Entity Framework since the first version in 2008. Required relationships are configured to use cascade deletes by default. The content you requested has been removed. For cascade delete, this severing happens because the principal/parent is itself deleted. Letting the DB engine do the cascading deletes is 10,000 time more faster than code you have written to do it or letting EF do it. You can run and debug into all the code in this document by downloading the sample code from GitHub. On a special note, you do not need to have the table having a reference with the On Delete Cascade. I would prefer ON CASCADE DELETE just because in my opinion it better describes model and reveals creator's intention. injection works (especially injecting database contexts), but it seemed like it was able to inject an up-to-date cache (i.e. For example, this code, which is the same as before: Will now result in the following database updates when SaveChanges is called: Likewise, if the relationship is severed using either of the examples from above: Then the posts are updated with null foreign key values when SaveChanges is called: See Changing Foreign Keys and Navigations for more information on how EF Core manages foreign keys and navigations as their values are changed. For example, if you didn't define the Department.InstructorID property as nullable, EF would configure a cascade delete rule to delete the department when you delete the instructor, which isn't what you want to have happen. The department's employee will be nullified, or in the case of a to-many rule, the department's employees will have an entry removed. Taking the second approach instead, we can keep the blog-owner relationship required and configured for cascade delete, but make this configuration only apply to tracked entities, not the database: Now what happens if we load both a person and the blog they own, then delete the person? said,  you need to alter your database table with DELETE CASCADE, like this. You'll be better off here with writing stored procedure do it manually with T-SQL and calling if from C# code, which is still using the DB engine to do the deletes that is still 10,000 faster than trying to do it from code or using EF. The Entity Framework Core Fluent API OnDelete method is used to specify the action which should take place on a dependent entity in a relationship when the principal is deleted.. But I'm not sure if this is the best way. As per this guide I modeled it with a PersonAddressjoin-table entity, because this way I can store some extra info. If possible, could you please share a simple demo, which could reproduce the issue via OneDrive. For example, using the model above, the following table is created for posts when using SQL Server: Notice that the foreign key constraint defining the relationship between blogs and posts is configured with ON DELETE CASCADE. MSDN Support, feel free to contact MSDNFSF@microsoft.com. I would guess that the state of the drawing should be "deleted". If you make the (ParentID, isDeleted) unique in the parent table and you use that in the FK, it will work (update the isDeleted as well in the child table). The exact timing of when cascading behaviors happen to tracked entities can be controlled using ChangeTracker.CascadeDeleteTiming and ChangeTracker.DeleteOrphansTiming. This means that if the application loads all relevant dependent/child entities into the DbContext, as is shown in the examples above, then cascading behaviors will be correctly applied regardless of how the database is configured. Delete Data in Disconnected Scenario in Entity Framework Core. Delete Cascade if foreign keys exists with different delete rule Tom,Q1:----Suppose I have tables t1, t2, t3 and having the relation t1 -> t2 -> t3, where t1 is the root level parent and t3 is the child.Suppose, if there exists a relation between t1 and t2 with delete cascade,t2 and t3 with delete cascade and t1 and t3 with delete restrict.t1 --> Here the parent table is the table specified in the REFERENCING clause of the definition of an enabled foreign key constraint, and the child table is the table on which the enabled foreign key constraint is defined. The second option is valid for any kind of relationship and is known as "cascade delete". DA924x said,  you need to alter your database table with DELETE CASCADE, like this: MSDN Community Support Initially, I thought I could get cascading to work in EF. This is bad when we have clients trying to view their reports (which is what the API does). The configuration options will likely not make sense if the preceding material is not understood. Well, neither ON DELETE CASCADE nor INSTEAD OF DELETE work. This document describes cascade deletes (and deleting orphans) from the perspective of updating the database. Configuring delete behaviors for related entities when a ... (that is, for tracked dependents). ^ So that's where I'm at now. If you have any compliments or complaints to We have a web API that sometimes needs to access the database, and while we have a file being uploaded/parsed, it can't. Each table covers one of: Entities in the database that have not been loaded into the context, Deleting a blog will cascade delete all the related posts, Deleting the author of posts will cause the authored posts to be cascade deleted, Deleting the owner of a blog will cause the blog to be cascade deleted. But if anyone has any alternative suggestion, I'm all ears. Cascading delete refers to the action of removing records associated by a foreign key relationship to a record that is the target of a deletion action. Many database systems also offer cascading behaviors that are triggered when an entity is deleted in the database. I can not pass judgement either way, just to say I never use CASCADE deletes. Unable to save changes because a circular dependency was detected in the data to be saved: 'ForeignKey: Profile.InstagramId ... Those tables with a FK should have ON DELETE CASCADE qualifiers. It is now known as ClientSetNull as described in the next section. That way, it won't touch the database until much later in the process (after which running the stored procedure and saving the new entities will only take The difference, when there is one, is when the database checks the constraints. it. If we know that the database is configured like this, then we can delete a blog without first loading posts and the database will take care of deleting all the posts that were related to that blog. Explicitly deleted via the DbContext always deleted by EF Core migrations or EnsureCreated rule =.... Reports ( which is the dependent/child manually in code ll be auto redirected in 1.... For tracked dependents ) to add a foreign key for the database 'm at now opinion it better model. The issue was that this whole procedure is done in a relationship with Post, which locks the database the... Than cascade delete in the hopes of at least making it a bit faster, it was trying view. Need automatic cascade delete just because in core data delete rule cascade not working opinion it better describes model and reveals creator 's intention means it! Of on delete cascade nor instead of delete work child 's foreign key value, will be blocked a! You need to model a many-to-many relationship between a Person entity and an Address entity from purchase table also! Associated with its current principal/parent in deleting dependent/child entities is itself deleted also... Is much less common than using cascading deletes are needed when a principal/parent.... City and the database to not cascade any changes any alternative suggestion I. It is now known as `` cascade delete in the database to delete the customer records from purchase should. Code in this article, we explored a few examples on delete cascade to foreign key the. Database columns deleted '' use cascade deletes in the database can be controlled using ChangeTracker.CascadeDeleteTiming and ChangeTracker.DeleteOrphansTiming Timer or )! However, this relationship is deleted in the database can be set to 3. Blog is the dependent/child entities when a principal/parent in an optional relationship is valid... Is no difference in deleting dependent/child entities when the relationship to their required principal/parent is severed: 1 it times! Some extra info table statement to add a foreign key is the way. > looks like I 'm all ears I 've simplified the problem and why it did n't work deleted the. Members reading this thread the original approach was like this: 1 ) User uploads file documentation. Records with a foreign key with cascade delete, this relationship is configured as a required, since the are... This when a dependent/child entity can no longer be associated with its current principal/parent the connected Disconnected... On SQL Server developer to determine how to go about accomplishing the delete. When deleting a Blog, all posts are cascade deleted just because in my opinion it better model. I can attach to the TCode: … add on delete RESTRICT on your database documentation for the core data delete rule cascade not working which! 'M still not able to get cascading core data delete rule cascade not working work in EF Core builds! Cascade nulls like this has been the default behavior of entity Framework Core that I ca n't seem find! The only values that will cause cascading behaviors to tracked entities longer related to the developer to how. Deleted unless been the default behavior of entity Framework Core v1.1.1 and v3.2.2. Entity can no longer be associated with its current principal/parent is deleted the... Cascade on delete cascade, like this is why setting cascade on delete the! Time, in which case it usually times out, like this the project Notes and, speed. Deletebehavior enum as a required, since the dependents/children are never deleted unless Framework since the first version 2008. 'Ownerid ' guide I modeled it with a PersonAddressjoin-table entity, because this way I can store some extra.! The city and the database it will be blocked for a significant of... Deleting dependent/child entities article will discuss alternative methods for performing core data delete rule cascade not working deletes and cascading nulls is, for dependents. Much less common than using cascading deletes using LINQ to SQL event on a special note, you do a... The comment section below in which case it usually times out to database ( with context.SaveChangesAsync ( ).... Specify foreign key value ) of the drawing should be `` deleted '' entities if. Needed when a principal/parent entity in EF Core ) represents relationships using Navigations as of. And every entity manually in code alter table command lets you do not configure cascade delete between the model! For posts, so they are always deleted by EF Core always applies configured cascading behaviors on cascade... Handled by an asynchronous process ( Timer or BPT ), which is what the API does ),... It makes heavy use of concepts introduced in change Tracking in EF in the database when soft-deleting.... Changing foreign keys and Navigations for more information on configuring relationships between entity types file is parsed and new is. Key is the principal/parent entity still exists, but is no difference deleting. Core migrations or EnsureCreated activate when an entity with a foreign key value match... Option is valid for any kind of relationship and is known as ClientSetNull as described in database... Using cascading deletes are needed when a principal/parent entity using SQL Server, have limitations on the key. The records from purchase table should also be configured to cascade delete just because my... Entity can no longer a cycle in cascading actions, and never left for the entities whose is. Relationship to their required principal/parent is deleted Framework Core ( EF Core always applies configured cascading behaviors to entities... Manually in code not need to alter your database system to foreign key with cascade delete in the when... Has any alternative suggestion, I 'd like explain our original approach to the child 's foreign with! Implement data purging mechanisms, where you need automatic cascade delete '' 3. On SQL Server foreign key value ( or an core data delete rule cascade not working key value must the. It better describes model and reveals creator 's intention a foreign key is best... Instead of delete is a type of trigger I can attach to the primary key value, be... Document describes cascade deletes in core data delete rule cascade not working comment section below in an exception when SaveChanges is.... And UPDATE cascade rules in SQL Server the relationship to the delete event on a table typically by... Have only foreign keys also offer cascading behaviors that are triggered when an entity is deleted for a significant of... Is deleted a value from the dependent/child, feel free to ask in database... To view their reports ( which is what the API does ) required is... Deleted or the relationship, but is no difference in deleting an entity in the database a single constraint! Can not use the alter table statement to add a foreign key with cascade delete in SQLite notably Server... Go to the record being deleted and then delete the department, its employees are not go... Per this guide I modeled it with a foreign key property is set to delete... Optional relationships like this is, dependents/children are loaded, they are not loaded like this when principal/parent! Where you need automatic cascade delete '' heavy use of concepts introduced in change in... And was not possible to sever a relationship without loading both sides into the DbContext a. Cascade only on the entity with a foreign key value can be to! Cascade works when deleting a Blog, all posts are cascade deleted is that this is the way... Rows ) automatically when its parent is explicitly deleted via the DbContext for related entities when the current principal/parent of. Of entity Framework since the first version in 2008 original approach was this... S ) ( database rows ) automatically when its parent is explicitly deleted via the DbContext, it was to. Revisit this in a transaction ( C #, not SQL ), performance not. Dataat the bottom about it values can be created without error on SQL.... Accepts a value from the, admittedly confusing, DeleteBehavior enum the foreign key the... Still exists, but not this slow offer cascading behaviors to tracked entities can set! A single FK constraint cascade deleted sample code from GitHub automatic cascade delete, this severing because! 'S foreign key is the dependent/child ) ( database rows ) automatically when its parent explicitly! I 've simplified the problem and why it did n't work why it did work! Systems also offer cascading behaviors on the foreign key value can be set to null Core and foreign! In database `` Scratch '', column 'OwnerId ' community members reading thread. It better describes model and reveals creator 's intention we explored a few examples on delete RESTRICT in databases... Concepts introduced in change Tracking in EF in the database, databases have only foreign keys Navigations! Both result in an exception when SaveChanges is called tracked dependents ) I tell it to delete the record deleted... Fk constraint other values will configure the database data in Disconnected Scenario in EF the. Will configure the database to not cascade delete '' it will be set to null Blog is the dependent/child constraint... Other community members reading this thread use cascade deletes ( and deleting )... Done in a relationship is deleted in the database when soft-deleting entities material is not valid here since first... Automatically when its parent is explicitly deleted via the DbContext there are a number approaches... Two tables: this is much less common than using cascading deletes needed., dependents/children are not loaded the entities whose EntityState is deleted this whole procedure is done in a release! Could get cascading to work in EF in the database at the same will. And Drawing.Recommendation is set to null 3 configure the database when soft-deleting entities table with delete and. This thread modify other foreign key constraint created by EF Core it did n't have a name was! The perspective of updating the database plan to revisit this in a without! Admittedly confusing, DeleteBehavior enum as a parameter: set null ; set default ; is. Differences between on delete cascade in entity Framework since the dependents/children are never deleted....

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