Which method in DbContext is used to save changes to the database?
- CommitChanges()
- SaveChanges()
- SubmitChanges()
- UpdateDatabase()
In Entity Framework, the SaveChanges() method in the DbContext is used to persist changes made to entities to the underlying database. When you modify, add, or delete entities in a DbContext, you need to call SaveChanges() to ensure that these changes are reflected in the database. This method executes SQL statements necessary to synchronize the state of the entities with the database, committing the changes within a transaction if all changes succeed.
Describe the behavior of DbContext when DbSet.Attach() is used on an entity.
- Attaches the entity and marks it as modified in the DbContext.
- Attaches the entity to the DbContext in an unchanged state.
- Detaches the entity from the DbContext, allowing it to be re-attached with changes.
- Throws an exception if the entity is already being tracked by the DbContext.
When DbSet.Attach() is used on an entity in Entity Framework's DbContext, it attaches the entity to the context in an unchanged state. This means that the entity is considered to exist in the database in its current state, and any changes made to it will not be tracked by the context unless explicitly marked as modified. This is useful when working with entities that are not being modified but need to be included in queries or related operations.
To query the database using LINQ in Entity Framework, you typically use the ________ property of DbContext.
- Context
- Data
- DbSet
- Query
In Entity Framework, to query the database using LINQ, you typically use the DbContext class's Set property, which provides access to the entities of a specific type. The Set property allows you to perform LINQ queries against the database.
The ________ method of DbContext can be overridden to configure domain classes using Fluent API.
- Configure
- Customize
- Mapping
- OnModelCreating
In Entity Framework, the OnModelCreating method of DbContext can be overridden to configure domain classes using Fluent API. This method is called when the model for a derived context has been initialized, allowing you to specify how the model should be configured.
In Entity Framework, ________ loading can be achieved by using the Include method with DbSet queries.
- Deferred
- Eager
- Immediate
- Lazy
In Entity Framework, eager loading can be achieved by using the Include method with DbSet queries. Eager loading allows you to retrieve related entities along with the main entities in a single query, reducing the number of database round trips and improving performance.
In a scenario where multiple users are modifying the same data, how does DbContext ensure data integrity?
- Automatic conflict resolution
- Explicit locking
- Optimistic concurrency control
- Pessimistic concurrency control
DbContext utilizes optimistic concurrency control to ensure data integrity in scenarios where multiple users are modifying the same data. This approach relies on versioning and optimistic locking to detect and handle conflicts, minimizing the risk of data inconsistency.
When implementing a complex transaction involving multiple DbSet operations, how does DbContext manage these operations to ensure data consistency?
- DbContext applies compensating transactions for rollback
- DbContext employs distributed transactions for consistency
- DbContext ensures atomicity of transactions
- DbContext uses savepoints to isolate operations
DbContext ensures atomicity of transactions when dealing with complex transactions involving multiple DbSet operations. This ensures that either all operations within the transaction are successfully completed, or none of them are, maintaining data consistency.
Consider a scenario where a large dataset needs to be processed efficiently. How would you optimize DbContext to handle this?
- Disable change tracking
- Implement lazy loading for better memory management
- Increase command timeout for longer processing
- Use batch processing for bulk operations
To optimize DbContext for processing large datasets efficiently, batch processing is recommended. By grouping multiple operations into a single batch, it reduces the overhead of round trips to the database, resulting in improved performance.
In which approach do you create database tables directly from your code models?
- Code First
- Database First
- Entity First
- Model First
Code First approach involves creating database tables directly from code models. It allows developers to define their domain model using C# or VB.NET classes, and the database schema is generated based on these classes during runtime. This approach provides flexibility and control over the database schema, making it suitable for scenarios where the database evolves with the application.
Which Entity Framework approach involves designing the database schema in a visual designer before generating the code?
- Code First
- Database First
- Entity First
- Model First
Model First approach involves designing the database schema visually using Entity Framework Designer in Visual Studio before generating the code. Developers can create entity types, relationships, and mappings using the designer, and then the corresponding code classes are generated from the model. This approach is useful when the database schema is finalized early in the development process.