CRUD Reading One Entity

There are several overloads for reading a single entity

• Find - Find an entity by it's id, or null.
• Get - Find an entity by it's id, or throw an exception.
• GetFirstOrDefault - Find the first matching entity by some conditions, or null.
• GetFirst - Find the first matching entity by some conditions, or throw an exception.
• GetSingleOrDefault - Find the only matching entity by some conditions, or null.
• GetSingle - Find the only matching entity by some conditions, or throw an exception.

Find

// Synchronous
TEntity Find<TEntity>(object id, int? commandTimeout = null);

// Asynchronous
Task<TEntity> FindAsync<TEntity>(object id, int? commandTimeout = null, CancellationToken cancellationToken = default);

Find an entity by it's id, or null if it doesn't exist. The type of the id should match the type of the primary key of the TEntity - e.g. if the primary key is a int, then the id should also be an int. If the primary key is a composite key, then the id should be an object which has the properties of the composite key.

Examples

Find an entity with a primary key of 12:

[Table("Users")]
public class UserEntity
{
    public int Id { get; set; }
    public string Name { get; set; }
}

...

var entity = database.Find<User>(12);
// or
var entity = await database.FindAsync<User>(12);

MS-SQL 2012 +

SELECT [Id], [Name]
FROM [Users]
WHERE [Id] = 12

PostgreSQL

SELECT id, name
FROM user
WHERE id = 12

Get

// Synchronous
TEntity Get<TEntity>(object id, int? commandTimeout = null)
    where TEntity : class;

// Asynchronous
Task<TEntity> GetAsync<TEntity>(object id, int? commandTimeout = null, CancellationToken cancellationToken = default)
    where TEntity : class;

Get an entity by it's id, or throws an exception if it doesn't exist.

📝 Find and Get are identical, except that Get throws an exception when the entity does not exist, similar to FirstOrDefault() vs First()

Examples

Get an entity with a primary key of 12:

[Table("Users")]
public class UserEntity
{
    public int Id { get; set; }
    public string Name { get; set; }
}

...

var entity = database.Get<User>(12);
// or
var entity = await database.GetAsync<User>(12);

MS-SQL 2012 +

SELECT [Id], [Name]
FROM [Users]
WHERE [Id] = 12

PostgreSQL

SELECT id, name
FROM user
WHERE id = 12