Class ValueObjectCheckConstraints

Namespace: AdCodicem.ValueObjects.EntityFrameworkCore
Assembly: AdCodicem.ValueObjects.EntityFrameworkCore.dll

Reads the code of the rule a CHECK constraint written by AddValueObjectCheckConstraints refused a row under, from the error the database provider throws.

public static class ValueObjectCheckConstraints

Inheritance

object ← ValueObjectCheckConstraints

Inherited Members

object.Equals(object?), object.Equals(object?, object?), object.GetHashCode(), object.GetType(), object.MemberwiseClone(), object.ReferenceEquals(object?, object?), object.ToString()

Remarks

Each constraint the convention writes is named after its rule, CK_{table}_{column}_{rule}, or CK_{table}_{column}_{rule}_{hash} when the name was shortened to the provider's limit or kept apart from another, and the rule maps to the code Validate reports for it: MinLength to , Minimum and Maximum to , KnownValues to and Pattern to . The name is read off the error, never off the model: a compiled model holds no check constraint.

Only an error reporting a violated CHECK constraint is read: PostgreSQL's SQL state 23514, whose constraint Npgsql names in ; SQL Server's error 547, whose number SqlClient states in in every language, the name read off its message, quoted or not; SQLite's CHECK constraint failed. An error that names a constraint for another reason, such as the "There is already an object named …" of a migration, carries no code. A constraint declared by hand under a name of the same shape is read as the convention's, since its name says the same rule; a name holding a space or a quotation mark is read on PostgreSQL only, which names it apart from its message.

The code is the only thing carried: the column is in the constraint's name unless it was shortened, in SQL Server's message, and, for SaveChanges, the entity is in DbUpdateException.Entries; neither the value object's type, which no name holds, nor the value is.

Methods

TryGetCode(Exception, out string?)

Reads the code of the rule a CHECK constraint of AddValueObjectCheckConstraints refused, from the provider's error or from one an exception wraps.

public static bool TryGetCode(Exception exception, out string? code)

Parameters

exception Exception

The exception, as it was caught: the provider's, or the DbUpdateException around it.

code string?

The code, or null when no exception of the chain reports such a refusal.

Returns

bool

true when a code was found.

Remarks

Each exception is read in turn, from exception down its chain, since Entity Framework Core fails SaveChanges with a DbUpdateException around the provider's error; the first reporting a violated constraint of the convention gives the code.

It reads the error whoever sent the command: Entity Framework Core without , Dapper, a bulk library or ADO.NET. With it, finds the same code, which the interceptor stores in the provider's error, but on an error Entity Framework Core hands no interceptor: on SQL Server, that of a raw SQL query writing rows it reads back, SqlQuery or FromSql over OUTPUT, which SqlClient reports while the rows are read. This reads the code there too.

Exceptions

ArgumentNullException

exception is null.