这是indexloc提供的服务，不要输入任何密码
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Catch exception instead of trying to check if the history repository exists #3294

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Merged
merged 1 commit into from
Sep 23, 2024
Merged

Catch exception instead of trying to check if the history repository exists #3294

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70 changes: 54 additions & 16 deletions src/EFCore.PG/Migrations/Internal/NpgsqlHistoryRepository.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,22 +75,8 @@ private RelationalCommandParameterObject CreateRelationalCommandParameters()
/// doing so can result in application failures when updating to a new Entity Framework Core release.
/// </summary>
protected override string ExistsSql
{
get
{
var stringTypeMapping = Dependencies.TypeMappingSource.GetMapping(typeof(string));

return
$"""
SELECT EXISTS (
SELECT 1 FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON n.oid=c.relnamespace
WHERE n.nspname={stringTypeMapping.GenerateSqlLiteral(TableSchema ?? "public")} AND
c.relname={stringTypeMapping.GenerateSqlLiteral(TableName)}
)
""";
}
}
=> throw new UnreachableException(
"We should not be checking for the existence of the history table, but rather creating it and catching exceptions (see below)");

/// <summary>
/// This is an internal API that supports the Entity Framework Core infrastructure and not subject to
Expand Down Expand Up @@ -194,6 +180,58 @@ public override string GetEndIfScript()
END $EF$;
""";

/// <summary>
/// Calls the base implementation, but catches "table not found" exceptions; we do this rather than try to detect whether the
/// migration table already exists (see <see cref="ExistsAsync" /> override below), since it's difficult to reliably check if the
/// migration history table exists or not (because user may set PG <c>search_path</c>, which determines unqualified tables
/// references when creating, selecting).
/// </summary>
public override IReadOnlyList<HistoryRow> GetAppliedMigrations()
{
try
{
return base.GetAppliedMigrations();
}
catch (PostgresException e) when (e.SqlState is "3D000" or "42P01")
{
return [];
}
}

/// <summary>
/// Calls the base implementation, but catches "table not found" exceptions; we do this rather than try to detect whether the
/// migration table already exists (see <see cref="ExistsAsync" /> override below), since it's difficult to reliably check if the
/// migration history table exists or not (because user may set PG <c>search_path</c>, which determines unqualified tables
/// references when creating, selecting).
/// </summary>
public override async Task<IReadOnlyList<HistoryRow>> GetAppliedMigrationsAsync(CancellationToken cancellationToken = default)
{
try
{
return await base.GetAppliedMigrationsAsync(cancellationToken).ConfigureAwait(false);
}
catch (PostgresException e) when (e.SqlState is "3D000" or "42P01")
{
return [];
}
}

/// <summary>
/// Always returns <see langword="true" /> for PostgreSQL - it's difficult to reliably check if the migration history table
/// exists or not (because user may set PG <c>search_path</c>, which determines unqualified tables references when creating,
/// selecting). So we instead catch the "table doesn't exist" exceptions instead.
/// </summary>
public override bool Exists()
=> true;

/// <summary>
/// Always returns <see langword="true" /> for PostgreSQL - it's difficult to reliably check if the migration history table
/// exists or not (because user may set PG <c>search_path</c>, which determines unqualified tables references when creating,
/// selecting). So we instead catch the "table doesn't exist" exceptions instead.
/// </summary>
public override Task<bool> ExistsAsync(CancellationToken cancellationToken = default)
=> Task.FromResult(true);

private sealed class NpgsqlMigrationDatabaseLock(IHistoryRepository historyRepository) : IMigrationsDatabaseLock
{
/// <summary>
Expand Down