Trying to use the provided solution by @Bassam Alugili: Didn't work. In this link http://code.msdn.microsoft.com/CSASPNETUniqueConstraintInE-d357224a I'm going to update the answer to explain why I think that. Setting unique Constraint with fluent API? Covariant derivative vs Ordinary derivative, Sci-Fi Book With Cover Of A Person Driving A Ship Saying "Look Ma, No Hands!". public class User { public int UserId { get; set; } public string Username { get; set; } } public class Ctp5Context : DbContext { public DbSet<User> Users { get; set; } protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity . Also note the nameof() syntax. rev2022.11.7.43014. Else its created with VARCHAR(MAX) which cannot have a index? With Entity Framework 6.1, you can now do this: [Index ("IX_FirstAndSecond", 1, IsUnique = true)] public int FirstColumn { get; set; } [Index ("IX_FirstAndSecond", 2, IsUnique = true)] public int SecondColumn { get; set; } The second parameter in the attribute is where you can specify the order of the columns in the index. Entity Framework Core with Multiple Foreign Key On Same Column, Stop requiring only one assertion per unit test: Multiple assertions are fine, Going from engineer to entrepreneur takes more than just good code (Ep. Third approach: By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. Allow Line Breaking Without Affecting Kerning. Fastest Entity Framework Extensions Bulk Insert Bulk Delete Bulk Update Bulk Merge Accepted Answer Using a query type is probably the right answer if you aren't updating the table, but it would be safe to simply configure the model as mb.Entity<MyEntity> ().HasKey ( x => new { x.Time, x.Col2 } ); But it doesn't work. https://entityframework.net/knowledge-base/32827800/composite-key-and-using-multiple-column-attributes-in-entity-framework-6#answer-0. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. c. map one entity to its underlying table and one to the view. Add the following configurations in your DbContext and then add a migration and update the database accordingly. Not the answer you're looking for? Try (B) first, creating a separate view because it requires the least amount of change to both code and DB schema (you aren't fiddling with underlying tables, or affecting stored procedures). However, the DocumentId doesn't save the correct InvoiceId, CreditNoteId, DebitNoteId. from outside when I receive this kind of exception I will catched and than maybe reporting the error and break the process or shutdown the application. Entity Splitting lets you combine data coming from multiple tables into a single class and it can only be used with tables that have a one-to-one relationship between them. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. If he wanted control of the company, why didn't Elon Musk buy 51% of Twitter shares instead of 100%? Your second workaround is much like my suggestion, and I think the best one in his scenario given that he needs to minimize the changes to the DB schema. Accepted Answer. I think that the Entity Framework 4 in its current state is not the right tool do work with legacy databases but if he needs to use EF4 at all costs, then I would just create another view, and use it as an entity, if that view is complicated enough, otherwise if the view is just a simple select over one single table, then I'd just use the original table as an entity. Entity type 'Business_attrib2object' has composite primary key defined with data annotations. Movie about scientist trying to find evidence of soul. Hi Matthew thanks for the update. But I'm having trouble mapping an entity to a table with a composite primary key. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. But the fluent associations don't seem to provide a way of specifying which field is referenced. @Clyde It's a bummer for sure. Each element has SortOrder. EF 6: In EF 6, the Key attribute along with the Column attribute can be applied to multiple properties of an entity class which will create composite primary key columns in the database. Thanks for the Fluent API implementation. (clarification of a documentary). Which finite projective planes can have a symmetric incidence matrix? When did double superlatives go out of fashion in English? =\. I personally prefer not having any EF artifacts carried over into my entity classes. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. rev2022.11.7.43014. 503), Mobile app infrastructure being decommissioned, 2022 Moderator Election Q&A Question Collection. To learn more, see our tips on writing great answers. Id) and an explicitly defined key. For example, we have company with employees and only we have a unique constraint on (name, company) for any employee: Note that I also used @niaher extension for unique index annotation. Then. Set this up via the fluent API if you like, but for easy illustration I've used the data annotations. Changing DB: Create another view, just like the vwContacts, say vwContactsLegacy, and map it to a class in wich the key is the LegacyKeyField, and map vwContacts to the original view, using KeyField as the key. However, with extension methods, you can specify what to do behind the scenes, and have a simple call to it. What do you call an episode that is not closely related to the main plot? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. so that you can't refer to your drivers byDriverId and Type Modified 4 years, 1 month ago. Entity Framework Code First Mapping Foreign Key Using Fluent API. This can potentially become a bit messy as you'd have to remember which object comes from which context. Use anonymous type object instead of 2 separated statements: From Microsoft Docs: EntityTypeConfiguration.HasKey Method. But I need it working for foreign keys! As your table definition, the TransactionLog.DocumentId's value must be exist in the three tables (Invoice CreditNote DebitNote) at the same time. How to help a student who has internalized mistakes? I actually got an error having two different objects mapped to the same database table. Solution 2. When working with Code First, you define your model by defining your domain CLR classes. Recently added a composite key with the uniqueness of 2 columns using the approach that 'chuck' recommended, thank @chuck. let say it has been work before long time! Before I searched a lot time but I got nothing about this. To learn more, see our tips on writing great answers. Be wary of DB unique constraints with EF. In my project I have a table Translation that can have translations for any model. I differentiate the Foreign Key with DocumentTypeId: 1 - Invoice, DriversToVehicle_Driver_Target_DriversToVehicle_Driver_Source: : The number of properties in the Dependent and Principal Roles in a relationship constraint must be identical. How can I force entity framework to insert identity columns? e.g. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Summary To learn more, see our tips on writing great answers. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. [Entity Framework Core] In your traditional database, there are two ways to enforce the restriction that "the value of this column should be unique": Unique constraints Unique indexes If you attempt to insert a duplicate column value, the database will throw an error and abort the operation. Zaheer Ul Hassan entity-framework-6 azure-mobile-services Does subclassing int to forbid negative integers break Liskov Substitution Principle? Stupid question: Why so you start all your name by "IX_" ? Thanks for your input. It will bring the " Manage Nuget Packages " window. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. You can select to an anonymous type, for example. Ask Question Asked 4 years, 1 month ago. Adding the second view does seem to be the path of least resistance here -- thank you for all your detailed research! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 503), Mobile app infrastructure being decommissioned, 2022 Moderator Election Q&A Question Collection, Add a column with a default value to an existing table in SQL Server. How to help a student who has internalized mistakes? I think maybe the Foreign Key's direction is wrong. The class represents data in a database. SSH default port not changing (Ubuntu 22.10), Replace first 7 lines of one file with content of another file. I hope that this is more of a help than a disillusion, EF is a powerfull toy, but it is far from perfect though I think it's going to get much better in the next versions. 2 - DebitNote, You may wish to create indexes on other properties to speed up data retrieval: If he wanted control of the company, why didn't Elon Musk buy 51% of Twitter shares instead of 100%? Why am I being blocked from installing Windows 11 2022H2 because of printer driver compatibility, even with no printers installed? Connect and share knowledge within a single location that is structured and easy to search. Changing the value through queries will ensure consistency. Does protein consumption need to be interspersed throughout the day to be useful for muscle building? Viewed 3k times . EF CORE CODE FIRST PRIMARY KEY COMPOSITE KEY PRIMARY KEY, Create composite in multiple foreign key using entity framework. How should I map these classes to provide, so that one product can be seen in multiple categories? Entity Framework will fail the save b/c it's trying to update sortorders one at a time. You can then use this property inside the index definition. you must refer to them by both, not just one.DriverId I guess you have a wrong relationship there. By default, indexes are created for foreign keys and alternate keys. a. map your objects to their underlying tables and alter your "get/read" methods on repositories and service classes pull from the joined view -or- b. create a second view and map each object to their appropriate view. It is also difficult to suggest a solution without knowing what exactly is the scenario that you have a problem with: querying, loading, saving, etc. Let's take a look at the following example in which Student information is mapped into two tables. rev2022.11.7.43014. SqlException from Entity Framework - New transaction is not allowed because there are other threads running in the session, Entity Framework: table without primary key, Fastest Way of Inserting in Entity Framework, Entity Framework - Include Multiple Levels of Properties, No Entity Framework provider found for the ADO.NET provider with invariant name 'System.Data.SqlClient'. One Invoice may have multiple TransactionLog. I differentiate the Foreign Key with DocumentTypeId: 1 - Invoice, 2 - DebitNote, 3 - CreditNote I scaffold the . I have tried everything that you can imagine, and found that most solutions won't work in this version of EF maybe in future versions it supports referencing another entity by using an unique field, but this is not the case now. Composite keys are not covered by conventions or data annotation attributes. But you'll have to deal with index violations in the business layer anyhow. EDIT 2: "New things have come to light, man" - His Dudeness. (as one would expect), Just note that this answer applies to EF Core and is not available in EF6.x. Why are standard frequentist hypotheses so uninteresting? The entity type has multiple properties with the [Key] attribute. You can also configure multiple properties to be the key of an entity - this is known as a composite key. Find centralized, trusted content and collaborate around the technologies you use most. How does reproducing other labs' results work? One convention of Code First is implicit key properties; Code First will look for a property named "Id", or a combination of class name and "Id", such as "BlogId". The statement I use is: var dataset2 = from recordset in entities.processlists where recordset.ProcessName == processname select recordset.ServerName, recordset.ProcessID, recordset.Username; Obviously, this doesn't even compile. Both of these are available in entity framework. Unfortunately, the truth revealed is that you cannot accomplish what you seek without altering SQL due to limitations on EF 4.1+ code first. Find centralized, trusted content and collaborate around the technologies you use most. My profession is written "Unemployed" on my passport. OK, stick to the unique index then. The second approach to create Unique Constraints with EF Core by using Alternate Keys. A Contact object is exposed in the database as an updateable view. How can you prove that a certain file was downloaded from a certain website? @JJS - I got it to work where one of the properties was a foreign key.. by any chance is your key a varchar or nvarchar? EF6, Composite Key, is annotation enough? If the primary key is made up of multiple properties then specify an anonymous type including the properties. More information: MSDN. Connect and share knowledge within a single location that is structured and easy to search. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Maybe EF4 is not the right tool for the job. Is this meat that I was told was brisket in Barcelona the same as U.S. brisket? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Choose Console App (.NET Framework), then provide location and a name (I typed PostgreCodeFirst ). Second approach: Also, you could have two objects at the same time, that represents the same thing on the backing storage, so say you load a vwContact and also a vwContactLegacy, changes both, and then try to save both you will have to care about this yourself. You have to use the Fluent API HasKey () function in EF Core. Edit I'm not sure this is actually possible, and this is why: The assumption is that a foreign key references a primary key. I think this may be possible using extension methods, although not directly through EF as @Matthew Walton mentioned in his edit above. In EF Core 3.x the columns for owned entity types mapped to the same table as the owner are always marked as . By the way, is it called AlternateKey as well? As I suggested in comment before, you won't be able to map them to a single view/table anyway so you have a couple options: a. map your objects to their underlying tables and alter your "get/read" methods on repositories and service classes pull from the joined view -or-. Asking for help, clarification, or responding to other answers. For instance: Page object has a child collection of Elements. Would you please show your entity type configuration / class references? In this case we can create two separate contexts Legacy and Non-legacy and map them accordingly. One thing has to be noted though: If the unique property is of type string then you have to set the MaxLength. 401. But then again, nothing stops you from adding the same EF code first object into 2 different contexts. thank you for the update please add a comment to @chuck answer. When applying code to pre-existing fields in a table in a database, I'm attempting to construct a composite key utilizing two columns; I now encounter the following issue when attempting to execute a new migration: The number of properties in the Dependent and Principal Roles in a relationship constraint must be identical. you can find the code for unique key data annotation: The problem for this approach; How can I combine them? Thanks for the input -- I don't have time to run through this today, but I'll try to get to it within a week. This means the caller can change one but not the other and have an entity with incorrect data. The HasColumnName attribute is applied to a property to specify the database column that the property should map to when the entity's property name and the database column name differ. You should be able to do this with two different objects to represent the Contact view. How can foreign key constraints be temporarily disabled using T-SQL? I have updated the quesition thanks for help! The code sample provides is done in a Windows form project but can be used in any project type from desktop to web solutions. How do I view the SQL generated by the Entity Framework? Did the words "come" and "home" historically rhyme? The only way to configure composite keys is to use the HasKey method. Is it possible to convert non-primitive value object containing two fields? Is it possible for a gas fired boiler to consume more energy when heating intermitently versus having heating at all times? HasKey is a Fluent API method, which allows us to configure the primary key & composite primary of an entity in EF Core. But the are not keys I just want them as Unique the key should be the Id? Do we ever see a hobbit use their natural ability to disappear? I don't think you're going to get a seamlessly functional EF model without changing your database though. Why was video, audio and picture compression the poorest when storage space was the costliest? Only this approached looked cleaner to me: You should place Index attrib on top of the entity classs and define your multiple keys in string[]. 503), Mobile app infrastructure being decommissioned, 2022 Moderator Election Q&A Question Collection. What's the best way to roleplay a Beholder shooting with its many rays at a Major Image illusion? Next, let's add PostgreSQL Entity Framework provider - add the latest version of . In such cases, we need use an anonymous object as the argument to the HasAlternateKey as shown below. Connect and share knowledge within a single location that is structured and easy to search. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. What is the rationale of climate activists pouring soup on Van Gogh paintings of sunflowers? I have 3 tables with relationship to the same TransactionLog.DocumentId column. By using the .HasKey() method, a set of properties can be explicitly configured as the composite primary key of the entity. When the Littlewood-Richardson rule gives only irreducibles? The problem of this approach is the following: It needs DbMigration so what do you do if you don't have it? Miguel's answer below seems to be roughly the same suggestion so I would start here if it's possible. if the Legacy db is using LegacyKeyField, then perhaps the legacy db will be read only. Site design / logo 2022 Stack Exchange Inc; user contributions licensed under CC BY-SA. Execution plan - reading more records than in table. For general information about relationships in EF and how to access and manipulate data using relationships, see Relationships & Navigation Properties. Get monthly updates by subscribing to our newsletter! How will this affect other things that link to it going forward (by this, I mean the code first in the classes)? Open Visual Studio and click File menu, then New -> Project. The Fluent API HasIndex Method The Entity Framework Core Fluent API HasIndex method is used to create a database index on the column mapped to the specified entity property. Asking for help, clarification, or responding to other answers. Option (A), while it fits EF's intention best (entities mapped to tables), it means to get your joined view you must alter your C# services/repositories to work with the EF entities for Add, Update, Delete operations, but tell the Pull/Read-like methods to grab data from the joint views. Why does sending via a UdpClient cause subsequent receiving to fail? I'll have to test this out -- I've always set up the relationship from the 'one' side of the one-to-many relationship. So when you update one thing, the other one could be changed or not, it depends if the objects is cached or not. HasKey(t => t.Id); Property(t => t.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); My only guess to why this is happening is that the word "Snapshot" has some special coding in Entity Framework and it's ignoring some kind of convention because of that name. It is the least invasive and least risky from my perspective. The best way to do that is by an Any() query, because it minimizes the amount of transferred data: Beware that this check alone is never enough. Also due to the history of the database, this Contact view has two different keys, one from a legacy system. Another thing, the third approach may not necessarily be the best. Stack Overflow for Teams is moving to its own domain! Using this method does not enable you to perform any conversion of the data at run time. How do I view the SQL generated by the Entity Framework? Inheriting from a base that has no key definitions: all root classes must have keys, so that inherited classes share this common key that is how inheritance works in EF4. Additionally you could (should) check for unique values before saving changes. Many tutorial suggest to map the GUID to string instead of guid, I dont know why. How does DNS work when it comes to addresses after slash? +1 - I think we're saying the exact same thing. Introduction Entity Framework Core has a method DbSet<TEntity>.Find(Object[]) used to find a entity by primary key but does not have a method to find multiple keys. If you do this and then you wind up having an update that flip-flops the values of one of the columns that is part of the unique key, entity frameowkr will fail on the save unless you add a whole transaction layer. Foreign Key mapping to composite keys in entity framework, Entity Framework Code First Using One column as Primary Key and another as Auto Increment Column, Entity Framework 6 where did key and column attributes go, Entity framework composite primary key - how to get order of columns, EntityFramework - Composite Key Table with FK to another Composite Key Table, Update Database using Entity Framework having primary key on multiple Columns, Entity Framework 6 inverting column order for composite foreign keys, Entity Framework, Load multiple entities by primary key in a single query while still using caching, How create composite foreign key to table with composite primary key, Entity Framework composite key delete with one primary key. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To create a composite primary key with multiple columns, you have to override DbContext.OnModelCreating () and then specify all of the columns included in the primary key, like this: protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Actor> () .HasKey (nameof (Actor.FirstName), nameof (Actor.LastName)); } Can you help me? Would a bicycle pump work underwater, with its air-input being above water? 3 - CreditNote. Fastest Way of Inserting in Entity Framework, Entity Framework - Include Multiple Levels of Properties. I have edited the question by adding the OnModelCreating, Looks like you want table-per-hierarchy inheritance. EF Core does not support creating a composite key using the Key attribute. Choose the correct package and click " Install ". We can get the reference to the ModelBuilder, when we override the onmodelcreating method of the DbContext. as of yourDrivers Composite keys can only be configured using the Fluent API; conventions will never set up a composite key, and you can not use Data Annotations to configure one. So than LEGACY_OBJECT becomes VW_LEGACY OBJECT with CONTACT.ContactId brought over, then: I personally would go with creating "mapper views" with CustomerId on legacy tables, as it's cleaner from c# layer perspective and you can make those views look like real tables. Composite keys can only be configured using the Fluent API - conventions will never setup a composite key and you can not use Data Annotations to configure one. Okay, I separated the Type into its own class. Return Variable Number Of Attributes From XML As Comma Separated Values. Or do I now need to link to this class using both keys in other entities? Table of Contents Primary Key Composite Primary Key Reference Primary Key The default convention in EF Core uses the property with the name id or with the name <className>ID. As for your two calls to HasKey on vwContact, they can't both be the definitive key for the object, so it's either a compound key which features both of them, or pick one, or there's another field you haven't mentioned which is the real primary key. : Thanks to you, I learned this usage. Is this meat that I was told was brisket in Barcelona the same as U.S. brisket? I tried all of the following things, that didn't work: Without DB changes: Map to the table that is source of the view in question that is, if vwContact is a view to Contacts table, then you can map a class to Contacts, and use it by setting the key to the KeyField, and another class mapping to the vwContacts view, with the key being LegacyKeyField. This article presents a language extension method which provides this missing functionality. using System.Data.Entity; // .. public class PersonContext : DbContext { // .. Fluent API uses the Modelbuilder instance to configure the domain model. Composite primary keys can only be set using 'HasKey' in 'OnModelCreating'.' This is the code for xunit. var dataset2 = ( from recordset in entities.processlists where recordset.ProcessName == processname select new { serverName = recordset.ServerName, processId = recordset.ProcessID, username = recordset.Username }).ToList (); Or you can create a new class that will represent your . If you're using Code-First, you can implement a custom extension HasUniqueIndexAnnotation. This is my mapping class. is of a type that is invalid for use as a key column in an index. and Vehicle This property will map to a primary key column in the database. Entity Framework Core supports composite keys - primary key values generated from two or more fields in the database. So, for example: the Product table has modeltype id 1.To get all translations for a product with id 317, I search for translations with Model . Maybe an easy question, but can't find it easily so forgive me =) I try to select multiple columns. From here it's not really possible to say what the right option there is. Stack Overflow for Teams is moving to its own domain! The HasColumnType method enables mapping to different representations of the same basic type. Please try to make the InvoiceId, CreditNoteId, and DebitNoteId with different value. Can humans hear Hilbert transform in audio?
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