Reflexe

Nette Database provides tools for database structure introspection using the class Nette\Database\Reflection\Reflection. This allows you to retrieve information about tables, columns, indexes, and foreign keys. Reflection can be used for schema generation, creating flexible database-driven applications, or general database tools.

You can obtain the reflection object from a database connection instance:

$reflection = $connection->getReflection();

Working with tables

Using reflection we can browse all tables in the database:

getTables(): Nette\Database\Reflection\Table[]

Returns an associative array where the key is the table name, and the value is an array of table metadata.

// Listing all table names
foreach ($reflection->getTables() as $table) {
	echo $table['name'] . "\n";
}

hasTable (string $name): bool

Returns true if the table exists, otherwise false.

// Checking table existence
if ($reflection->hasTable('users')) {
	echo "The 'users' table exists";
}

getTable (string $name): Nette\Database\Reflection\Table

Returns the Nette\Database\Reflection\Table object representing the given table. If the table does not exist, it throws an exception Nette\Database\Exception\MissingTableException.

// Retrieving a specific table
$table = $reflection->getTable('users');

Information about columns

The Nette\Database\Reflection\Table object, obtained by calling getTable(), allows you to retrieve detailed information about table columns.

getColumns(): Nette\Database\Reflection\Column[]

Returns an array of Nette\Database\Reflection\Column objects representing the table columns.

getColumn (string $name): Nette\Database\Reflection\Column

Returns the Nette\Database\Reflection\Column object representing the given column. If the column does not exist, it throws an exception Nette\Database\Exception\MissingColumnException.

The Column object provides the following properties:

• name: The column name.
• nativeType: The database-specific column data type.
• type: The normalized column data type (see constants Nette\Utils\Type).
• nullable: true if the column can contain NULL, otherwise false.
• primary: true if the column is part of the primary key, otherwise false.
• autoIncrement: true if the column is auto-increment, otherwise false.
• default: The column's default value, or null if not defined.
• vendor: An array with additional database-specific information.

// Iterating through all columns in the 'users' table
$table = $reflection->getTable('users');
foreach ($table->getColumns() as $column) {
	echo "Column: " . $column->name . "\n";
	echo "Type: " . $column->nativeType . "\n";
	echo "Allows NULL: " . ($column->nullable ? 'Yes' : 'No') . "\n";
	echo "Default value: " . ($column->default ?? 'None') . "\n";
	echo "Is primary key: " . ($column->primary ? 'Yes' : 'No') . "\n";
	echo "Is auto-increment: " . ($column->autoIncrement ? 'Yes' : 'No') . "\n";
}

// Retrieving a specific column
$idColumn = $table->getColumn('id');

Indexes and primary keys

getIndexes(): Nette\Database\Reflection\Index[]

Returns an array of Nette\Database\Reflection\Index objects representing the table indexes.

getIndex (string $name): Nette\Database\Reflection\Index

Returns the Nette\Database\Reflection\Index object representing the given index. If the index does not exist, it throws an exception Nette\Database\Exception\MissingIndexException.

getPrimaryKey(): ?Nette\Database\Reflection\Index

Returns the Nette\Database\Reflection\Index object representing the table's primary key, or null if the table has no primary key.

The Index object provides the following properties:

• name: The name of the index.
• columns: An array of Nette\Database\Reflection\Column objects representing the columns that are part of the index.
• unique: true if the index is unique, otherwise false.
• primary: true if the index is the primary key, otherwise false.

$table = $reflection->getTable('users');

$printColumnNames = fn(array $columns) => implode(', ', array_map(fn($col) => $col->name, $columns));

// Listing all indexes
foreach ($table->getIndexes() as $index) {
	echo "Index: " . ($index->name ?? 'Unnamed') . "\n";
	echo "Columns: " . $printColumnNames($index->columns) . "\n";
	echo "Is unique: " . ($index->unique ? 'Yes' : 'No') . "\n";
	echo "Is primary key: " . ($index->primary ? 'Yes' : 'No') . "\n";
}

// Retrieving the primary key
if ($primaryKey = $table->getPrimaryKey()) {
	echo "Primary key: " . $printColumnNames($primaryKey->columns) . "\n";
}

Foreign keys

getForeignKeys(): Nette\Database\Reflection\ForeignKey[]

Returns an array of Nette\Database\Reflection\ForeignKey objects representing the table's foreign keys.

getForeignKey (string $name): Nette\Database\Reflection\ForeignKey

Returns the Nette\Database\Reflection\ForeignKey object representing the given foreign key. If the foreign key does not exist, it throws an exception Nette\Database\Exception\MissingForeignKeyException.

The ForeignKey object provides the following properties:

• name: The name of the foreign key.
• localColumns: An array of Nette\Database\Reflection\Column objects representing the local columns that make up the foreign key.
• foreignTable: A Nette\Database\Reflection\Table object representing the foreign table that the foreign key references.
• foreignColumns: An array of Nette\Database\Reflection\Column objects representing the foreign columns the foreign key references.

$table = $reflection->getTable('books');

$printColumnNames = fn(array $columns) => implode(', ', array_map(fn($col) => $col->name, $columns));

foreach ($table->getForeignKeys() as $fk) {
	echo "Foreign key: " . ($fk->name ?? 'Unnamed') . "\n";
	echo "Local columns: " . $printColumnNames($fk->localColumns) . "\n";
	echo "References table: {$fk->foreignTable->name}\n";
	echo "References columns: " . $printColumnNames($fk->foreignColumns) . "\n";
}