This is called Cascade deleti… I suppose this is why setting cascade on delete in the data model doesn't work? This article will discuss alternative methods for performing cascading deletes using LINQ to SQL. If you use entity framework database first, As This entity's foreign key value must match the primary key value (or an alternate key value) of the related principal/parent entity. but when I delete my Service the data in table Lexikon will still be in it. CRUD operation oData This step-by-step post describes how to UPDATE, DELETE & MODIFY record into table using GET_ENTITY method in oData service. But I'm not sure if this is the best way. For example: Notice that there is no Include for posts, so they are not loaded. I need to model a many-to-many relationship between a Person entity and an Address entity. This probably stems from past experience of a root delete cascading to an empty database (luckily I … I use the [CascadeDelete] attribute like follows in an entity, which successfully adds the "Cascade" delete rule to the Parent-Child relation. It makes heavy use of concepts introduced in Change Tracking in EF Core and Changing Foreign Keys and Navigations. With large files, it will be blocked All other values will configure the database to not cascade any changes. Drawing.RecommendationId is still set to the ID of the deleted recommendation and Drawing.Recommendation is set to null. For orphans, the principal/parent entity still exists, but is no longer related to the dependent/child entities. I managed to get cascading to work in EF but I'm still getting an error: "The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. This is because while EF Core represents relationships using navigations as well of foreign keys, databases have only foreign keys and no navigations. In the following example, a cascade delete is configured on the relationship between Blog and Post, so the post entity is deleted from the database. I am running into an issue DELETE CASCADE in Entity Framework Core that I can't seem to find a good solution to. Record of Table SCARR: Step 1: Go to the TCode:… Initially, I thought I could get cascading to work in EF. to be much quicker than doing manual deletions for every single entity (most likely not as fast as the stored procedure but hopefully faster than manual deletions through-and-through). 3) File is parsed and new data is made into new entities. This document describes cascade deletes (and deleting orphans) from the perspective of updating the database. 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 Well, neither ON DELETE CASCADE nor INSTEAD OF DELETE work. If possible, could you please share a simple demo, which could reproduce the issue via OneDrive. Databases don't typically have any way to automatically delete orphans. After the database is synchronized with this setting, Telerik Data Access will issue DELETE statements only against the main table and will rely on the backend to delete the related records from the other tables. When I was trying to manually delete all drawings, my code looked like this: This worked (no errors) but it's extremely slow. Visit our UserVoice Page to submit and vote on ideas! 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. See Changing Foreign Keys and Navigations for more information. 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. seconds). Using anything other than cascade delete for required relationships will result in an exception when SaveChanges is called. Consider an example of Customer Registration. Cascade Delete - EF Core. Well, neither ON DELETE CASCADE nor INSTEAD OF DELETE work. 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. Make sure to fully understand these concepts before tackling the material here. the database) took minimal time. Prior to EF Core it didn't have a name and was not possible to change. ASP.NET Forums / Data Access / ADO.NET, Entity Framework, LINQ to SQL, NHibernate / Cascade delete entitiyframework core Cascade delete entitiyframework core RSS 1 reply 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. The conflict occurred in database "Scratch", table "dbo.Blogs", column 'OwnerId'. 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 Cascade delete allows the deletion of a row to trigger the deletion of related rows automatically. Then the delete successfully removes both the city and the zip code. for a significant amount of time, in which case it usually times out. Do not configure cascade delete in the database when soft-deleting entities. MSDN Support, feel free to contact MSDNFSF@microsoft.com. On a special note, you do not need to have the table having a reference with the On Delete Cascade. The child/dependent can be deleted 2. I don't think you will see a performance difference between trigger and using cascade. See Relationships for more information on modeling relationships. ... rows primary key value, will be deleted automatically. Use the ON DELETE CASCADE option if you want rows deleted from the child table when the DELETE or MERGE statement removes corresponding rows from the parent table. EF Core covers a closely related concept and implements several different delete behaviors and allows for the configuration of the delete behaviors of individual relationships. 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? Cascade delete on one-to-one relationships not working #147. From what I gather, it seems that during a transaction like this, as soon as Even though deleting through a stored procedure is by far the fastest way to do it, it might be acceptable if getting cascading to work in EF is at least faster than doing all deletes in EF manually. The EF Core in-memory database does not currently support cascade deletes in the database. Let's understand it with an easy example. There are two ways to handle this situation: Taking the first approach with our example, we could make the blog-owner relationship optional by giving it a nullable foreign key property: An optional relationship allows the blog to exist without an owner, which means cascade delete will no longer be configured by default. 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 … I'm still not able to get cascading to work in EF and so deleting all the The Delete value is commonly used when you implement data purging mechanisms, where you need automatic cascade delete between the whole model.. 4) Once file parsing is done, new entities are saved to database (with context.SaveChangesAsync()). For example, when an author is deleted, it will remove all the related books automatically as … This can result in circular cascade delete rules, which will cause an exception when you try to add a migration. This one for example: In other words: Do all the parsing of the file first, THEN run the delete stored procedure and save. EF Core always applies configured cascading behaviors to tracked entities. LINQ to SQL does not specifically handle cascading deletes and it is up to the developer to determine whether or not that action is desired. Similarly, we cannot create INSTEAD OF DELETE trigger on the table when a foreign key CASCADE DELETE rule already exists on the table. We agreed that we would accept a bit of slowness, but not THIS slow. DA924x said,  you need to alter your database table with DELETE CASCADE, like this: Our application is database first. 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. We actually did have a stored procedure doing the work in the beginning, but due to complications in what we're trying to do, we're looking for an alternative. ^ So that's where I'm at now. record in EF. If delete rule for Department.employees is also nullify, then when you delete the department, its employees are not let go. For example: See Relationships for more information on configuring relationships between entity types. Before proceeding with the demo, here is summary of the effects for update and delete operations: This is an invalid state, and will cause a referential constraint violation in most databases. You can handle the cascade only on the Entity DbContext with OnModelCreating. However, in this case the posts are deleted by the database because it has been configured with ON DELETE CASCADE when it was created. Given all this, there are a number of approaches we tried. Looks like I'm stuck deleting each and every entity manually in code. Since data purging mechanisms are typically handled by an asynchronous process (Timer or BPT), performance is not a concern. There are three actions EF can take when a principal/parent entity is deleted or the relationship to the child is severed: 1. 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 will not be set to null. it works well. Here's a super simplified version of my model: User {UserID, Name} Recipe {RecipeID, UserID} Ingredient {IngredientID, UserID} RecipeIngredient {RecipeID, IngredientID} *RecipeIngredient is … But when management wants to delete the customer records from primary registration table, the records from purchase table should also be deleted. I'm working on an ASP.NET MVC 6 project with Entity-Framework Core (version "EntityFramework.Core": "7.0.0-rc1-final") backed by a SQL Server 2012 express DB.. is NOT what's supposed to happen if EF has cascading on delete working properly. Delete rules are activate when an object of the entity with the delete rule is deleted. Hopefully that works. Despite what NO ACTION may imply, both of these options cause referential constraints to be enforced. 2) Delete stored procedure runs to delete old data. injection works (especially injecting database contexts), but it seemed like it was able to inject an up-to-date cache (i.e. You’ll be auto redirected in 1 second. Cascade - dependents should be deleted; Restrict - dependents are unaffected; SetNull - the foreign key values in dependent rows should update to NULL There are two options to avoid this referential constraint violation: The first option in only valid for optional relationships where the foreign key property (and the database column to which it is mapped) must be nullable. 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. I set cascade delete on the parent record in the parent table using the database administration tool like MS SQL Server Management Studio and let the database engine do the deletes when I use the delete to the parent 1) User uploads file. This can be beneficial to other community members reading this thread. it hits the database, the database is locked until the transaction is complete. Post.BlogId is a foreign key property, the value of which must match the Post.Id primary key of the post to which the blog belongs. SaveChanges in this case will delete just the blog, since that's the only entity being tracked: This would result in an exception if the foreign key constraint in the database is not configured for cascade deletes. The difference, when there is one, is when the database checks the constraints. 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. You can not use the ALTER TABLE statement to add a foreign key with cascade delete in SQLite. Optional relationships have nullable foreign key properties mapped to nullable database columns. 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. An entity with a foreign key is the child or dependent entity in the relationship. 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. 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 This means that it is usually not possible to sever a relationship without loading both sides into the DbContext. I was afraid someone might say that. EF Core will cascade the delete of the owner so that the blog is also deleted: However, if the blog is not loaded when the owner is deleted: Then an exception will be thrown due to violation of the foreign key constraint in the database: Microsoft.Data.SqlClient.SqlException: The DELETE statement conflicted with the REFERENCE constraint "FK_Blogs_People_OwnerId". Yes, ON UPDATE CASCADE will update only the columns used in the FK definition. The second option is valid for any kind of relationship and is known as "cascade delete". 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