Method SingleOrDefaultAsync

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SingleOrDefaultAsync<TEntity, T>(DbSet<TEntity>, Func<TEntity, T>, CancellationToken)

Returns the only value of specified database recordset column, or a default value if no record exists; this method throws an exception if more than one records exist.

Declaration
public static Task<T> SingleOrDefaultAsync<TEntity, T>(this DbSet<TEntity> dbSet, Func<TEntity, T> getColumn, CancellationToken ct = default(CancellationToken))

    where TEntity : class, IEntity, new()

    where T : Column, IColumn<DbReader>, new()
Parameters
Type Name Description
DbSet<TEntity> dbSet

The database recordset.
System.Func<TEntity, T> getColumn

Delegate to return the column from Database recordset.
System.Threading.CancellationToken ct

The async cancellation token.
Returns
Type Description
System.Threading.Tasks.Task<T>

The only or default value.
Type Parameters
Name Description
TEntity

The entity type of database recordset.
T

The data type of the column.