To make the ComplexDataModel migration work with existing data: In the ComplexDataModel migration class, update the Up method: Add the following highlighted code. If JavaScript cannot be disabled in the browser, try another browser. The DataType attribute conveys the semantics of the data as opposed to how to render it on a screen. A course may be taught by multiple instructors, so the CourseAssignments navigation property is a collection: The question mark (?) When migrations are run later in this tutorial, the name fields become nvarchar(50). Ideally, the join entity would have its own natural (possibly single word) name in the business domain. This feature was contributed by @RaymondHuy. The name fields have type Text. So, with the release of Asp.Net Core in the Year 2016, Microsoft also released a new version of the Entity Framework called Entity Framework Core. There are three easy ways to avoid this: A dependent can be made required by using the Required attribute on it's navigation: Or by specifying it is required in OnModelCreating: Dependents can be saved to a different table by specifying the tables to use in OnModelCreating: See the OptionalDependentsSample in GitHub for more examples of optional dependents, including cases with nested optional dependents. At a higher level, this means that either the DbContext of the factory can be injected into other D.I. An exception is thrown. Ideally, the join entity would have its own natural (possibly single word) name in the business domain. EF Core creates shadow properties for automatically created FKs. Notice that the first name field is called FirstMidName. White spaces are allowed while numbers, and special system. Make the dependent required. Translations have been implemented in the EF Core repo for SQL Server, SQLite, and Cosmos. The Pomelo.EntityFrameworkCore.MySql package can be added to the csproj file. Value conversions are configured in DbContext.OnModelCreating. (Optional), TypeName: Data type of a column. Don't make these code changes without a backup. I am not able to workaround by retrieving the date part in c# because consider following example: var result = context.Products .Select (p => p.SomeMappedSqlFunction (p.CreateDateTime. You can try compiling a large model and running a benchmark on it by downloading the sample code from GitHub. The logs show here use EnableSensitiveDataLogging() so that ID values are shown. The instructions specify when to build the app. The bottom line here is to avoid the case where an optional dependent can contain all nullable property values and shares a table with its principal. These should be placed into different folders and namespaces, as shown above. The FK and navigation properties reflect the following relationships: The navigation property is named Administrator but holds an Instructor entity: The ? For example: But no class for the PostTag table. For example: On SQL Server, the table generated is now: This moves the FistName and LastName columns are moved to the top, even though they are defined in a base type. For example: Value converters can be used to encrypt property values before sending them to the database, and then decrypt them on the way out. For example, show a calendar control, the locale-appropriate currency symbol, email links, and client-side input validation. Many thanks! For example: The EF Core codebase now uses C# nullable reference types (NRTs) throughout. The column name has changed from FirstMidName to FirstName. Therefore, we are reverting this change in EF Core 6.0 for the SaveChangesAsync method only. As mentioned above, EF Core ships with a set of pre-defined ValueConverter classes, found in the Microsoft.EntityFrameworkCore.Storage.ValueConversion namespace. These "period columns" represent the time range during which the data in the row existed. This means that a ValueComparer is needed so that EF Core can track and detect changes correctly. Here, we are going to explore both existing and custom options to run row SQL in Entity Framework Core but will focus more on extension method implementations using ADO.NET. Either don't save any instance with only default values or mark the incoming navigation as required in the model. The next section shows how to configure the composite PK. This limits the kinds of encryption that can be used. Running the app runs the DbInitializer.Initialize method. More info about Internet Explorer and Microsoft Edge, Microsoft.EntityFrameworkCore.Storage.ValueConversion, The string representation of the enum value, Parses the string as the given numeric type, Encoded date/time preserving DateTime.Kind, Invariant culture date/time string with offset, The GUID in 'dddddddd-dddd-dddd-dddd-dddddddddddd' format, Any conversion that requires only a type-cast. (This diagram was generated using EF Power Tools for EF 6.x. For example: Also, after a normal tracking query, the values from the period columns of the current data can be accessed from the tracked entities. See this GitHub comment 4076 for instructions on adding decimal comma. For example, this code: Deleting an item from the Cosmos database generates the CosmosEventId.ExecutedDeleteItem event. Only dictionaries with string keys are supported, Querying into the contents of primitive collections is not currently supported. How to assign same json property name, one having value and other being null? DepartmentID points to the related Department entity. In some cases that is great, but SQL DATE type is only 3 bytes. Note that just creating a DbContext instance does not cause the EF model to be initialized. Please vote () for, Value generation is not supported for most keys mapped through value converters. For example, consider an enum where its default value is "Unknown": However, the database may have null values when the breed is unknown. FKs are not nullable. Note that, in the general case, most databases only support ordering columns when the table is created. The Contoso University web app demonstrates how to create Razor Pages web apps using EF Core and Visual Studio. For example, the Instructor-to-Courses join table using this pattern would be CourseInstructor. The recommended practice for using fluent API or attributes: Some of the attributes used in this tutorial are used for: For more information about attributes vs. fluent API, see Methods of configuration. These translations were contributed by @Marusyk. For example, the following code requires the first character to be upper case and the remaining characters to be alphabetical: The preceding image shows the schema for the Student table. For example, consider a customer database for customers based in the United Kingdom. The next section shows how to configure the composite PK. However, sometimes it is useful to deal with temporary values directly. Make sure to read the SQL Server sparse columns documentation to ensure that sparse columns are the right choice for your scenario. The request units (RU) are included in these events whenever appropriate. There are some configurations that can only be done with attributes (MinimumLength). See Value Comparers for more information. If SSOX was opened previously, click the Refresh button. Many providers are now also exposing this command timeout in the connection string. If a name in the database had more than 50 characters, the 51 to last character would be lost. Many thanks! The Order property of ColumnAttribute can now be used to order columns when creating a table with migrations. Types that can't be null are automatically treated as required fields. There's a one-to-zero-or-one relationship between the Instructor and OfficeAssignment entities. The addition of the Column attribute changes the model backing the SchoolContext. This means that EF Core can snapshot and compare values without issue. Update Models/Enrollment.cs with the following code: The FK properties and navigation properties reflect the following relationships: An enrollment record is for one course, so there's a CourseID FK property and a Course navigation property: An enrollment record is for one student, so there's a StudentID FK property and a Student navigation property: There's a many-to-many relationship between the Student and Course entities. The [DataType] attribute is used to specify a data type that's more specific than the database intrinsic type. The model backing the SchoolContext no longer matches the database. EF Core can't automatically recognize InstructorID as the PK of OfficeAssignment because InstructorID doesn't follow the ID or classnameID naming convention. This is because the same value converter can be used for both nullable and non-nullable types, which is very useful for PK/FK combinations where the FK is often nullable and the PK is not. This is typically handled by serializing the object as it goes into the database, and then deserializing it again on the way out. The RegularExpression attribute is used to apply restrictions to the input. Therefore the. Navigate to the Students Index page. The preceding code adds a non-nullable DepartmentID FK to the Course table. Notice how the form has automatically rendered a validation error message in each field containing an invalid value. The most requested feature for EF Core 6.0 was support for SQL Server temporal tables. The Course entity has a Department navigation property. A large model typically means 100s to 1000s of entity types and relationships. Note: The Order parameter must be applied on all the properties with a different index, starting from zero. For example: GitHub Issue: #23719. Column data types. A department may or may not have an administrator. If the database update command is run, the following error is produced: In the next section, you see what to do about this error. See Enrollments and CourseAssignments for examples of how many-to-many join tables can be seeded. If all nullable properties contain a null value in database then an object instance won't be created in the query causing nested dependent's values to be lost. For example: Now any time this converter is used, the database column will be non-unicode with a max length of 20. The Create and Edit pages have no validation rules in them. This feature was contributed by @stevendarby. For example, by creating a DbSet property for the entity type: EntityTypeConfigurationAttribute types will not be automatically discovered in an assembly. Note that all the built-in converters are stateless and so a single instance can be safely shared by multiple properties. The only way to specify composite PKs to EF Core is with the fluent API. See Value Comparers for more information. An office assignment can't exist without an instructor. This is used in the OrderBy clause to sort the data, and then in a projection to include these values in the returned data. Microsoft.Data.Sqlite is following this trend with the Command Timeout connection string keyword. Get started with Razor Pages and EF Core shows advanced EF Core operations with Razor Pages. In this section, validation logic is added to the Movie model. The Budget column is defined using the SQL Server money type in the database: Column mapping is generally not required. Validation is applied consistently throughout the application, validation logic is defined in one place. Data models start out simple and grow. For example: This generates the following SQL, when using SQL Server: GitHub Issue: #17223. For example, this code: Retrieving items from the Cosmos database using a query generates the CosmosEventId.ExecutingSqlQuery event, and then one or more CosmosEventId.ExecutedReadNext events for the items read. EF Core 6.0 contains many improvements to the Azure Cosmos DB database provider. Update Data/SchoolContext.cs with the following code: The preceding code adds the new entities and configures the many-to-many relationship between the Instructor and Course entities. We made significant improvements to query performance for EF Core 6.0. The recommended practice for using fluent API or attributes: The following illustration shows the diagram that EF Power Tools create for the completed School model. DRY can help: The validation support provided by Razor Pages and Entity Framework is a good example of the DRY principle: The System.ComponentModel.DataAnnotations namespace provides: Update the Movie class to take advantage of the built-in [Required], [StringLength], [RegularExpression], and [Range] validation attributes. For example, consider the following model, where ContactInfo is owned by Customer and Address is in turned owned by ContactInfo: Now if ContactInfo.Phone is null, then EF Core will not create an instance of Address if the relationship is optional, even though the address itself may have data. However, byte arrays are a mutable reference type, which makes them somewhat painful to deal with. Sometimes it is necessary to execute a raw SQL query instead of using LINQ. Some common options are: Use dotnet ef migrations bundle --help to see all available options. Instead, typical first operations that cause the model to be initialized include calling DbContext.Add or executing the first query. Custom IModelCacheKeyFactory implementations are not supported. This can be useful when using TPH inheritance mapping where properties of a rarely used subtype will result in null column values for most rows in the table. The name fields have type nvarchar(MAX). For example: EF Core does not expose temporary values on entity type instances. EF Core chooses the appropriate SQL Server data type based on the CLR type for the property. The command timeout, which determines the maximum time to wait for a command to complete executing. Note that by default each migration is applied in its own transaction. This works the same way it always has done with relational providers. You may not be able to enter decimal commas in decimal fields. The Column attribute overrides the default convention. also provides client-side and server-side validation. This page contains an overview of interesting changes introduced in this release. For example, a general Money type that contains both the amount and the currency: This value object can be used in an entity type as before: Value converters can currently only convert values to and from a single database column. Times are no longer displayed. The HireDate attributes could be written as follows: The Courses and OfficeAssignment properties are navigation properties. But it's surprisingly complex using date data effectively if you want to let the user see dates and query data in their local time zone. Serialization can also be used to store a collection of primitive values. For example: Entity types in the Cosmos model can now be configured with the default time-to-live and time-to-live for the analytical store. For example: In both these cases, EF Core creates a shared entity typed based on Dictionary to act as the join entity between the two types. When the database is created, property names on the model are used for column names (except when the Column attribute is used). Similarly, the Post.BlogId foreign key property must be assigned a BlogKey. More info about Internet Explorer and Microsoft Edge, Introducing DevOps-friendly EF Core Migration Bundles, Announcing Entity Framework Core 6.0 Preview 6: Configure Conventions, Lazy loading and change-tracking proxies are not supported, The model must be manually synchronized by regenerating it any time the model definition or configuration change, Announcing Entity Framework Core 6.0 Preview 5: Compiled Models, Announcing Entity Framework Core 6.0 Preview 4: Performance Edition, Taking the EF Core Azure Cosmos DB Provider for a Test Drive, International Standard Book Number (ISBN), Value conversion to null in the store generates bad queries, Value conversion from null in the store generates bad queries, Value converters do not handle cases where the database column has multiple different values that convert to the same value, Allow value converters to change nullability of columns, A .NET 6 Minimal API Todo example Playground, changed the EF Core code in the 5.0 release, a common API for savepoints in ADO.NET providers, The creation of temporal tables using Migrations, Transformation of existing tables into temporal tables, again using Migrations, Restoring data from some point in the past, Model builder configuration for each property. Contoso University business rules state that an instructor can have at most one office. For example, consider a Blog entity with a ulong concurrency token: This can be mapped to a SQL server rowversion column using a value converter: SQL Server discards the DateTime.Kind flag when storing a DateTime as a datetime or datetime2. SET @WholeNumber = @WholeNumber + 1; -- Increment the variable. An office assignment only exists in relation to the instructor it's assigned to. 668. However, explicitly including the FK in the data model can make updates simpler and more efficient. We can create a keyless entity type to represent this: And define an DbSet property for it on the DbContext, along with sets for other top-level entity types: Then, in OnModelCreating, we can write a LINQ query that defines the data to be returned for CustomerDensities: This can then be queried just like any other DbSet property: GitHub Issue: #20173. For example: EF Core migrations will then mark the column as sparse. For example, we may want an interceptor that only applies to commands that come from SaveChanges: This filters the interceptor to only SaveChanges events when used in an application which also generates migrations and queries. For example, iterating through the customers and checking if the Address is null: Consider instead the case where no property off the address is required: Now it is possible to save both a customer with no address, and a customer with an address where all the address properties are null: However, in the database, these two cases are indistinguishable, as we can see by directly querying the database columns: For this reason, EF Core 6.0 will now warn you when saving an optional dependent where all of its properties are null. fetch the Department entity before an update. Update Models/Student.cs with the following highlighted code: The DataType attribute emits HTML 5 data- (pronounced data dash) attributes that HTML 5 browsers consume. By default, the date field is displayed according to the default formats based on the server's CultureInfo. Budget is for currency, and the money data type is more appropriate for currency. An instructor can teach any number of courses, so Courses is defined as a collection. With payload means that the Enrollment table contains additional data besides FKs for the joined tables. Some databases, including SQL Server, perform case-insensitive string comparisons by default. Types that can't be null are automatically treated as required fields. If a navigation property holds multiple entities: If ICollection is specified, EF Core creates a HashSet collection by default. The preceding image shows the schema for the Student table. This can now be configured using IsSparse in OnModelCreating. DateTime2 ); private readonly LocalDateTypeMapping _localDateTypeMapping = new LocalDateTypeMapping (); private readonly By default, NETs DateTime type is saved as SQL DATETIME2, which has a resolution of 100ns and take up 7 bytes. There's a one-to-zero-or-one relationship between the Instructor and OfficeAssignment entities. The [RegularExpression] attribute is used to limit what characters can be input. In Entity Framework Core, there are multiple options to run raw SQL quires. Replace the code in Models/Student.cs with the following code: The preceding code adds a FullName property and adds the following attributes to existing properties: FullName is a calculated property that returns a value that's created by concatenating two other properties. Cascading delete can result in circular cascade delete rules. With the [Column] attribute, Student.FirstMidName in the data model maps to the FirstName column of the Student table. For example: This can be useful when multiple properties use the same conversion. Notice that times are not input or displayed along with dates. EF Core 6.0 natively maps collections of primitive types when using the Cosmos database provider. This example also shows how the same ColumnAttribute can be used to specify both the column name and order. For example, consider this EF Core code: The output from this code, with logging for connections turned on, is: Notice that the connection is opened and closed rapidly for each operation. There are a few known current limitations of the value conversion system: Removal of these limitations is being considered for future releases. However, a different database can be migrated by passing the connection string on the command line. Thanks for completing this introduction to Razor Pages. The model builder can be used to configure a table as temporal. For example, after making some updates and deletes to our data, we can run a query using TemporalAll to see the historical data: Notice how the EF.Property method can be used to access values from the period columns. Some attributes such as MinimumLength can't be applied with the fluent API. These changes may then trigger notifications which, for example, may have to run on the U.I. For example: The output is an executable suitable for your target operating system. EF string str = ex.InnerException.InnerException.Message; datetime2 datetime The StringLength attribute specifies the minimum and maximum length of characters that are allowed in a data field. For example, the following Tags table contains both nullable non-nullable string columns: This results in corresponding nullable and non-nullable string properties in the generated class: Similarly, the following Posts tables contains a required relationship to the Blogs table: This results in the scaffolding of non-nullable (required) relationship between blogs: Finally, DbSet properties in the generated DbContext are created in a NRT-friendly way. This feature was contributed by @RaymondHuy. characters are not allowed. For example, on SQL Server: GitHub Issue: #23163. With the existing database, there are two approaches to changing the database: Either choice works for SQL Server. All queries using temporal operators are no-tracking by default, so the returned entity here is not tracked. The OfficeAssignment PK is also its foreign key (FK) to the Instructor entity. These are always read from and written to the database using an 8-byte array. container, just as in previous versions: Note that context instances created by the factory must be explicitly disposed. UnicodeAttribute is ignored when the database system supports only Unicode types. A bundle needs migrations to include. Expand the Tables node. JavaScript can be disabled using browser's developer tools. The errors are enforced both client-side, using JavaScript and jQuery, and server-side, when a user has JavaScript disabled. The CLR decimal type maps to a SQL Server decimal type. For example, converting strings to numbers will fail if the string values cannot be parsed as numbers. Hints for the view engine to format the data. For example: These are not trivial issues and for the query issues they are not easy to detect. For example, consider a converter that stores the enum values as their currency symbols: This can now be configured using the generic HasConversion method: Unambiguous many-to-many relationships between two entity types are discovered by convention. The sample data is used for testing. For example, the context used in the examples above contains both constructors: The PooledDbContextFactory type has been made public so that it can be used as a stand-alone pool for DbContext instances, without the need for your application to have a dependency injection container. The CourseAssignments and OfficeAssignment properties are navigation properties. EF core datetime2 conversion to datetime resulted in an out-of-range value. This allows these functions to be used with binary columns, or with columns mapped using a value converter. EF Core creates shadow properties for automatically created FKs. For student enrollment dates, all of the pages currently display the time of day along with the date, although only the date is relevant. In the sample app, only the date is displayed, without time. Many thanks! Circular cascade delete rules cause an exception when a migration is added. Attributes can control how classes and properties are mapped to the database. Vote for GitHub issue #11597 to have this limitation removed. Having validation rules automatically enforced by ASP.NET Core helps: Run the app and navigate to Pages/Movies. MinimumLength doesn't change the schema, it only applies a minimum length validation rule. By default, EF Core assumes that PK values are generated by the database. Set a break point in the OnPostAsync method of the Create or Edit page. For example: Starting with EF Core 6.0, the generic type can instead specify a value converter type. 587. By default, the browser renders data using the correct format based on the locale. Use the [RegularExpression] attribute to validate the format of the data. Latest version is This feature was contributed by @michalczerwinski. The tables created for SQL Server using migrations show how the configuration has been applied to all mapped columns: It is also possible to specify a default type mapping for a given type. Here is the T-SQL code: --Option 1. Create Models/CourseAssignment.cs with the following code: The Instructor-to-Courses many-to-many relationship requires a join table, and the entity for that join table is CourseAssignment. The model backing the SchoolContext no longer matches the database. The OfficeAssignment PK is also its foreign key (FK) to the Instructor entity. P.S.. "/> Disable JavaScript in the browser. The only way to specify composite PKs to EF Core is with the fluent API. The following code is an example of the fluent API: In this tutorial, the fluent API is used only for database mapping that can't be done with attributes. The way of handling the situation shown here is simplified for this tutorial. GitHub #4693 SQL Server This is the full-stack perf improvement, including improvements in the benchmark code, the .NET runtime, etc. Note: By convention, EF Core enables cascade delete for non-nullable FKs and for many-to-many relationships. Storing dates in persistent storage using UTC dates is a widely accepted best practice. WebEF Core 6.0 . Make the code less error prone, and easier to test and maintain. This section is optional. For example: It is typically not necessary to look at the generated bootstrapping code. EF Core 6.0 contains several improvements in the translation and execution of LINQ queries. (Cascade delete will take care of the Enrollment table.). To do this, define your value converter as a class: Then, override ConfigureConventions in your context type and configure the converter as follows: EF Core contains many pre-defined conversions that avoid the need to write conversion functions manually. In EF core released 27th June 2016 you can use fluent API for setting default value. Multiple rows are allowed for one instructor. For example: Notice that this time all three migrations were applied, since none of them had yet been applied to the production database. Microsoft.Data.Sqlite stores them as TEXT. For example, this code: Retrieving a single item from the Cosmos database using Find with a partition key generates the CosmosEventId.ExecutingReadItem and CosmosEventId.ExecutedReadItem events. This tutorial shows two approaches: The code in the updated DbInitializer adds seed data for the new entities. The following fluent API would set a restrict rule instead of cascade. The model in the GitHub repo referenced above contains 449 entity types, 6390 properties, and 720 relationships. EF Core doesn't require a FK property for a data model when the model has a navigation property for a related entity. In the sample application, only the date is displayed, without time. MinimumLength and Required allow whitespace to satisfy the validation. If supporting any of these features is critical to your success, then please vote for the appropriate issues linked above. After re-inserting the row Rainbow Dash, querying the historical data shows that the row was restored as it was at the given UTC time: EF Core migrations are used to generate database schema updates based on changes to the EF model. Some developers prefer to use the fluent API exclusively so that they can keep their entity classes "clean." There are some configurations that can only be done with the fluent API, for example, specifying a composite PK. A many-to-many join table without payload is sometimes called a pure join table (PJT). For Course entities, the user specifies the PK. The StringLength attribute doesn't prevent a user from entering white space for a name. Other options can be passed to the command line. In the Enrollment entity, the additional data besides FKs are the PK and Grade. I got this problem "The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value.\r\nThe statement has been terminated." [DataType] attributes aren't validation attributes. Circular cascade delete rules causes an exception when a migration is added. Many thanks! This means that the column order attribute cannot be used to re-order columns in an existing table. grayver Working example. The Required attribute must be used with MinimumLength for the MinimumLength to be enforced. In this section, the data model is customized using attributes. Value converters allow the rowversion to instead be mapped to a ulong property, which is much more appropriate and easy to use than the byte array. This allows, for example, a scoped instance of the DbContext to be resolved from the request scope, while the factory can be used to create multiple independent instances when needed. See Announcing Entity Framework Core 6.0 Preview 6: Configure Conventions on the .NET Blog for more discussion and examples of pre-convention model configuration. Value converters allow property values to be converted when reading from or writing to the database. Query tags allow adding a textural tag to a LINQ query such that it is then included in the generated SQL. Update Models/Student.cs with the following code: The Required attribute makes the name properties required fields. Update the Student.cs file with the following highlighted code: With the preceding change, Student.FirstMidName in the app maps to the FirstName column of the Student table. For example: The output from running this command includes a piece of code to copy-and-paste into your DbContext configuration to cause EF Core to use the compiled model. WebThe SQLite datetime function is a very powerful function that can calculate a date/time value, and return it in the format 'YYYY-MM-DD HH:MM:SS'. To force EF Core to create a new DB, drop and update the DB: Run Get-Help about_EntityFrameworkCore from the PMC to get help information. How to convert the month name in english text in datetime to arabic text in C#? DB generated PK values is generally the best approach. Many thanks! The ValidFrom columns (by default called PeriodStart) contains the UTC time that the row was inserted. In the above example, TypeName = "DateTime2" parameter is applied on the DateOfBirth property. The DataType attribute provides the following benefits that are not available in DisplayFormat: For more information, see the Tag Helper documentation. A null in a database column is always a null in the entity instance, and vice-versa. Rather than just warning, EF Core 6.0 disallows just cases of nested optional dependents. The way to handle this unambiguously is to ensure that the dependent has at least one required property. However, the fluent API can specify most of the formatting, validation, and mapping rules that can be done with attributes. Note: EF 6.x supports implicit join tables for many-to-many relationships, but EF Core doesn't. The model type is the .NET type of the property in the entity type. To support this, AddDbContextFactory now also registers the DbContext type as a scoped service. Using BenchmarkDotNet to measure, the average time to first query is 1.02 seconds on a reasonably powerful laptop. Now that you have an existing database, you need to think about how to apply changes to it. Microsoft.Data.Sqlite now supports this API, including: Using a savepoint allows part of a transaction to be rolled back without rolling back the entire transaction. Existing Options. Multiple rows are allowed for one course. Test validation using the Edit page, the same validation is applied. For example, the preceding prevents entering a movie with only two chars and doesn't allow special characters in Genre. If the Enrollment table didn't include grade information, it would only need to contain the two FKs, CourseID and StudentID. This default behavior can result in circular cascade delete rules. Especially when you have explicitely set the variable to null, the default doesn't even matter. Get started with Razor Pages and EF Core is an excellent follow up to this tutorial. For example: It's important to remember that the OwnsOne/OwnsMany configuration must be used if you need to further configure these owned types. For more information, see Generated Properties. For example: Which generates the following insert statements on SQL Server: Sometimes it is useful to have both a DbContext type and a factory for contexts of that type both registered in the applications dependency injection (D.I.) Notice that the column order values can have gaps, allowing ranges to be used to always place columns at the end, even when used by multiple derived types. Create Models/OfficeAssignment.cs with the following code: The [Key] attribute is used to identify a property as the primary key (PK) when the property name is something other than classnameID or ID. An instructor can teach any number of courses, so CourseAssignments is defined as a collection. For example, consider a Book entity type with a property for the International Standard Book Number (ISBN) in the form "ISBN 978-3-16-148410-0": Since ISBNs cannot contain any non-unicode characters, the Unicode attribute will cause a non-Unicode string type to be used. Save optional dependents to their own table, instead of sharing a table with the principal. For example: The --output-dir and --namespace options can be used to specify the directory and namespace into which the compiled model will be generated. This can be done by explicitly marking the values as temporary. Join tables without payload (PJTs) frequently evolve to include payload. This is achieved by creating a parallel "history table" into which timestamped historical data is stored whenever a change is made to the main table. Nothing prevents a user from entering white space to satisfy this validation. Each relationship line has a 1 at one end and an asterisk (*) at the other, indicating a one-to-many relationship. This means that DateTime values coming back from the database always have a DateTimeKind of Unspecified. The data model is customized by specifying formatting, validation, and database mapping rules. This validation can be disabled if necessary. In addition to new mapping attributes, EF Core 6.0 contains several other improvements to the model building process. The EF Core in-memory database will now throw an exception if an attempt is made to save a null value for a property marked as required. By starting with a descriptive entity name, the name doesn't need to change when the join table changes. For example, if the entity type is defined like so: Then the enum values will be saved as strings in the database without any further configuration in OnModelCreating. For example, the type Money in the model above is represented by read-only struct: This is then serialized to and from JSON using a custom value converter: This value converter can be configured once for all uses of Money: Notice also that additional facets can be specified for the string column into which the serialized JSON is stored. See Announcing Entity Framework Core 6.0 Preview 4: Performance Edition on the .NET Blog for a detailed discussion of query performance improvements in EF Core 6.0. For example, consider these entity types: In EF Core 5.0, these types would have been modeled for Cosmos with the following configuration: In EF Core 6.0, the ownership is implicit, reducing the model configuration to: The resulting Cosmos documents have the family's parents, children, pets, and address embedded in the family document. 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