feature: postgresql adapter schema converter

documentation/components/adapters/postgresql.md

@@ -400,3 +400,131 @@ df()
 | `pgsql_insert_options(...)`          | Configure insert behavior (conflicts, upsert)   |
 | `pgsql_update_options($primaryKeys)` | Configure update behavior (primary key columns) |
 | `pgsql_delete_options($primaryKeys)` | Configure delete behavior (primary key columns) |
+
+## Schema Conversion
+
+Two helpers convert between a Flow `Schema` and a PostgreSQL table definition:
+
+- `to_pgsql_schema_table()` turns a Flow `Schema` into a `Flow\PostgreSql\Schema\Table`, which can emit `CREATE TABLE`
+  (and related index/constraint) SQL via `toSql()`.
+- `pgsql_table_to_flow_schema()` turns a `Flow\PostgreSql\Schema\Table` back into a Flow `Schema`.
+
+Column types are resolved through the shared `EntryTypesMap` (Flow type → PostgreSQL column type), and per-column
+details — primary keys, unique constraints, indexes, length, precision/scale, defaults, identity, generated columns,
+and explicit type overrides — are driven by `PostgreSqlMetadata` entries attached to each schema definition.
+
+### Creating a Table from a Flow Schema
+
+`to_pgsql_schema_table()` returns a table definition; call `toSql()` on it and execute each statement to create the
+table:
+
+```php
+use Flow\ETL\Adapter\PostgreSql\PostgreSqlMetadata;
+
+use function Flow\ETL\Adapter\PostgreSql\to_pgsql_schema_table;
+use function Flow\ETL\DSL\{bool_schema, int_schema, json_schema, schema, str_schema};
+
+$table = to_pgsql_schema_table(
+    schema(
+        int_schema('id', metadata: PostgreSqlMetadata::primaryKey('pk_users')),
+        str_schema('name', metadata: PostgreSqlMetadata::length(120)),
+        str_schema('email', metadata: PostgreSqlMetadata::indexUnique('uq_users_email')),
+        bool_schema('active', metadata: PostgreSqlMetadata::default(true)),
+        json_schema('payload'),
+    ),
+    'users',
+);
+
+foreach ($table->toSql() as $sql) {
+    $client->execute($sql);
+}
+```
+
+By default the table is created in the `public` schema; pass a third argument to target another one:
+
+```php
+$table = to_pgsql_schema_table($schema, 'users', 'analytics');
+```
+
+### Steering the Conversion with Metadata
+
+`PostgreSqlMetadata` factories return `Metadata` objects you attach to a definition via the `metadata:` argument of the
+schema DSL helpers. Combine multiple entries with `merge()`:
+
+```php
+use Flow\ETL\Adapter\PostgreSql\PostgreSqlMetadata;
+use Flow\PostgreSql\Schema\IdentityGeneration;
+
+use function Flow\ETL\DSL\{float_schema, int_schema, schema, str_schema};
+
+$schema = schema(
+    int_schema('id', metadata: PostgreSqlMetadata::identity(IdentityGeneration::BY_DEFAULT)),
+    str_schema('sku', metadata: PostgreSqlMetadata::type('citext')),                    // explicit type override
+    float_schema('amount', metadata: PostgreSqlMetadata::precision(10)->merge(PostgreSqlMetadata::scale(2))),
+    int_schema('total', metadata: PostgreSqlMetadata::generated('price * quantity')),
+);
+```
+
+| Metadata                          | Effect on the generated column                             |
+|-----------------------------------|------------------------------------------------------------|
+| `PostgreSqlMetadata::type($name)` | Force a specific PostgreSQL type, bypassing the type map   |
+| `PostgreSqlMetadata::length($n)`  | Emit `varchar($n)`                                         |
+| `PostgreSqlMetadata::precision($p)` / `::scale($s)` | Emit `numeric($p, $s)`                   |
+| `PostgreSqlMetadata::default($v)` | Set a column `DEFAULT`                                      |
+| `PostgreSqlMetadata::primaryKey($name)` | Include the column in the table primary key          |
+| `PostgreSqlMetadata::indexUnique($name)` | Include the column in a named `UNIQUE` constraint   |
+| `PostgreSqlMetadata::index($name)` | Include the column in a named index                       |
+| `PostgreSqlMetadata::identity($generation)` | Make the column an identity column               |
+| `PostgreSqlMetadata::generated($expr)` | Make the column a generated column                    |
+
+Columns sharing the same primary key, unique constraint, or index name are grouped together, so composite keys are
+expressed by attaching the same name to several definitions.
+
+### Reading a Flow Schema back from a Table
+
+`pgsql_table_to_flow_schema()` takes a `Flow\PostgreSql\Schema\Table` and returns a Flow `Schema`. Combine it with the
+PostgreSQL library's catalog provider to derive a Flow schema from a live table:
+
+```php
+use function Flow\ETL\Adapter\PostgreSql\pgsql_table_to_flow_schema;
+use function Flow\PostgreSql\DSL\client_catalog_provider;
+
+$table = client_catalog_provider($client, ['public'])
+    ->get()
+    ->get('public')
+    ->table('users');
+
+$schema = pgsql_table_to_flow_schema($table);
+```
+
+> **Note:** The reverse conversion is intentionally lossy. Several Flow types collapse onto the same PostgreSQL type
+> (for example `json`, `list`, `map`, and `structure` all map to `jsonb`), so a column is mapped back to a single
+> canonical Flow type rather than its original one.
+
+### Customizing the Type Mapping
+
+Both helpers accept an optional `EntryTypesMap`. Its second constructor argument overrides the Flow type → PostgreSQL
+column type mapping (the first argument keeps overriding the value-binding types used by the loader):
+
+```php
+use Flow\ETL\Adapter\PostgreSql\EntryTypesMap;
+use Flow\PostgreSql\QueryBuilder\Schema\ColumnType;
+use Flow\Types\Type\Native\StringType;
+
+use function Flow\ETL\Adapter\PostgreSql\to_pgsql_schema_table;
+
+$table = to_pgsql_schema_table(
+    $schema,
+    'users',
+    typesMap: new EntryTypesMap([], [
+        StringType::class => ColumnType::varchar(255),  // default strings to varchar(255) instead of text
+    ]),
+);
+```
+
+### Schema Conversion DSL Functions Reference
+
+| Function                                                              | Description                                            |
+|-----------------------------------------------------------------------|--------------------------------------------------------|
+| `to_pgsql_schema_table($schema, $tableName, $databaseSchema, $typesMap)` | Convert a Flow `Schema` into a PostgreSQL `Table`   |
+| `pgsql_table_to_flow_schema($table, $typesMap)`                       | Convert a PostgreSQL `Table` into a Flow `Schema`      |

src/adapter/etl-adapter-csv/tests/Flow/ETL/Adapter/CSV/Tests/Unit/CSVLineReaderTest.php

@@ -7,7 +7,6 @@
 use Flow\ETL\Adapter\CSV\CSVLineReader;
 use Flow\ETL\Adapter\CSV\Tests\Double\LengthCapturingSourceStream;
 use Flow\Filesystem\Stream\MemorySourceStream;
-use PHPUnit\Framework\Attributes\TestWith;
 use PHPUnit\Framework\TestCase;
 
 use function Flow\Filesystem\DSL\path;

src/adapter/etl-adapter-postgresql/src/Flow/ETL/Adapter/PostgreSql/EntryTypesMap.php

@@ -25,27 +25,41 @@
 use Flow\ETL\Row\Entry\XMLEntry;
 use Flow\PostgreSql\Client\TypedValue;
 use Flow\PostgreSql\Client\Types\ValueType;
+use Flow\PostgreSql\QueryBuilder\Schema\ColumnType;
+use Flow\Types\Type;
+use Flow\Types\Type\Logical\DateTimeType;
+use Flow\Types\Type\Logical\DateType;
+use Flow\Types\Type\Logical\HTMLElementType;
+use Flow\Types\Type\Logical\HTMLType;
+use Flow\Types\Type\Logical\JsonType;
+use Flow\Types\Type\Logical\ListType;
+use Flow\Types\Type\Logical\MapType;
+use Flow\Types\Type\Logical\StructureType;
+use Flow\Types\Type\Logical\TimeType;
+use Flow\Types\Type\Logical\UuidType;
+use Flow\Types\Type\Logical\XMLElementType as LogicalXMLElementType;
+use Flow\Types\Type\Logical\XMLType;
+use Flow\Types\Type\Native\BooleanType;
+use Flow\Types\Type\Native\EnumType;
+use Flow\Types\Type\Native\FloatType;
+use Flow\Types\Type\Native\IntegerType;
+use Flow\Types\Type\Native\StringType;
 
 use function array_key_exists;
 use function array_merge;
+use function Flow\Types\DSL\type_boolean;
+use function Flow\Types\DSL\type_date;
+use function Flow\Types\DSL\type_datetime;
+use function Flow\Types\DSL\type_float;
+use function Flow\Types\DSL\type_integer;
+use function Flow\Types\DSL\type_json;
+use function Flow\Types\DSL\type_string;
+use function Flow\Types\DSL\type_time;
+use function Flow\Types\DSL\type_uuid;
+use function Flow\Types\DSL\type_xml;
 
 /**
- * Maps ETL Entry types to PostgreSQL types.
- *
- * Users can customize the mapping by passing overrides to the constructor.
- * Entry classes not in the map will throw TypeMappingException.
- *
- * Example usage:
- * ```php
- * // Use defaults
- * $map = new EntryTypesMap();
- *
- * // Override specific types
- * $map = new EntryTypesMap([
- *     IntegerEntry::class => ValueType::INT2,
- *     ListEntry::class => ValueType::TEXT_ARRAY,
- * ]);
- * ```
+ * Maps between Flow ETL types and PostgreSQL types.
  */
 final readonly class EntryTypesMap
 {
@@ -79,12 +93,19 @@
      */
     private array $typeMap;
 
+    /**
+     * @var array<class-string<Type<mixed>>, ColumnType>
+     */
+    private array $columnTypeMap;
+
     /**
      * @param array<class-string<Entry<mixed>>, ValueType> $overrides Entry class to ValueType mappings that override defaults
+     * @param array<class-string<Type<mixed>>, ColumnType> $columnTypeOverrides Flow Type class to ColumnType mappings that override defaults
      */
-    public function __construct(array $overrides = [])
+    public function __construct(array $overrides = [], array $columnTypeOverrides = [])
     {
         $this->typeMap = array_merge(self::DEFAULT_TYPES, $overrides);
+        $this->columnTypeMap = array_merge(self::defaultColumnTypes(), $columnTypeOverrides);
     }
 
     /**
@@ -108,4 +129,74 @@ public function mapEntry(Entry $entry): ?TypedValue
 
         return new TypedValue($entry->value(), $this->typeMap[$entryClass]);
     }
+
+    /**
+     * Maps a Flow type to a PostgreSQL DDL column type.
+     *
+     * @param Type<mixed> $type
+     *
+     * @throws TypeMappingException when the Flow type cannot be mapped
+     */
+    public function toColumnType(Type $type): ColumnType
+    {
+        $typeClass = $type::class;
+
+        if (!array_key_exists($typeClass, $this->columnTypeMap)) {
+            throw TypeMappingException::unsupportedFlowType($typeClass);
+        }
+
+        return $this->columnTypeMap[$typeClass];
+    }
+
+    /**
+     * Maps a PostgreSQL DDL column type back to a canonical Flow type.
+     *
+     * @throws TypeMappingException when the PostgreSQL type cannot be mapped
+     *
+     * @return Type<mixed>
+     */
+    public function toFlowType(ColumnType $columnType): Type
+    {
+        $name = $columnType->normalize()['name'];
+
+        return match ($name) {
+            'int2', 'int4', 'int8', 'smallserial', 'serial', 'bigserial' => type_integer(),
+            'float4', 'float8', 'numeric' => type_float(),
+            'bool' => type_boolean(),
+            'text', 'varchar', 'bpchar', 'bytea' => type_string(),
+            'date' => type_date(),
+            'time' => type_time(),
+            'timestamp', 'timestamptz' => type_datetime(),
+            'uuid' => type_uuid(),
+            'json', 'jsonb' => type_json(),
+            'xml' => type_xml(),
+            default => throw TypeMappingException::unsupportedColumnType($name),
+        };
+    }
+
+    /**
+     * @return array<class-string<Type<mixed>>, ColumnType>
+     */
+    private static function defaultColumnTypes(): array
+    {
+        return [
+            IntegerType::class => ColumnType::bigint(),
+            StringType::class => ColumnType::text(),
+            FloatType::class => ColumnType::doublePrecision(),
+            BooleanType::class => ColumnType::boolean(),
+            DateType::class => ColumnType::date(),
+            TimeType::class => ColumnType::time(),
+            DateTimeType::class => ColumnType::timestamptz(),
+            UuidType::class => ColumnType::uuid(),
+            JsonType::class => ColumnType::jsonb(),
+            ListType::class => ColumnType::jsonb(),
+            MapType::class => ColumnType::jsonb(),
+            StructureType::class => ColumnType::jsonb(),
+            EnumType::class => ColumnType::text(),
+            XMLType::class => ColumnType::xml(),
+            LogicalXMLElementType::class => ColumnType::xml(),
+            HTMLType::class => ColumnType::text(),
+            HTMLElementType::class => ColumnType::text(),
+        ];
+    }
 }

src/adapter/etl-adapter-postgresql/src/Flow/ETL/Adapter/PostgreSql/Exception/TypeMappingException.php

@@ -16,11 +16,27 @@ public static function ambiguousEntryType(string $entryClass): self
         ));
     }
 
+    public static function unsupportedColumnType(string $pgTypeName): self
+    {
+        return new self(sprintf(
+            'PostgreSQL type "%s" cannot be automatically mapped to a Flow type. Provide a column type override to map it explicitly.',
+            $pgTypeName,
+        ));
+    }
+
     public static function unsupportedEntryType(string $entryClass): self
     {
         return new self(sprintf(
             'Entry type "%s" is not supported for PostgreSQL mapping. Use withColumnType() to specify the target type explicitly or provide a custom EntryTypeMapper.',
             $entryClass,
         ));
     }
+
+    public static function unsupportedFlowType(string $flowTypeClass): self
+    {
+        return new self(sprintf(
+            'Flow type "%s" cannot be automatically mapped to a PostgreSQL column type. Provide a column type override to map it explicitly.',
+            $flowTypeClass,
+        ));
+    }
 }

src/adapter/etl-adapter-postgresql/src/Flow/ETL/Adapter/PostgreSql/PostgreSqlMetadata.php

@@ -0,0 +1,76 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Flow\ETL\Adapter\PostgreSql;
+
+use Flow\ETL\Schema\Metadata;
+use Flow\PostgreSql\Schema\IdentityGeneration;
+
+/**
+ * Per-column metadata keys understood by {@see SchemaConverter} when converting a Flow Schema to a
+ * PostgreSQL table.
+ */
+enum PostgreSqlMetadata: string
+{
+    case DEFAULT = 'pgsql_column_default';
+    case GENERATED = 'pgsql_column_generated';
+    case IDENTITY = 'pgsql_column_identity';
+    case INDEX = 'pgsql_column_index';
+    case INDEX_UNIQUE = 'pgsql_column_index_unique';
+    case LENGTH = 'pgsql_column_length';
+    case PRECISION = 'pgsql_column_precision';
+    case PRIMARY_KEY = 'pgsql_column_primary';
+    case SCALE = 'pgsql_column_scale';
+    case TYPE = 'pgsql_column_type';
+
+    public static function default(bool|float|int|string $value): Metadata
+    {
+        return Metadata::with(self::DEFAULT->value, $value);
+    }
+
+    public static function generated(string $expression): Metadata
+    {
+        return Metadata::with(self::GENERATED->value, $expression);
+    }
+
+    public static function identity(IdentityGeneration $generation = IdentityGeneration::ALWAYS): Metadata
+    {
+        return Metadata::with(self::IDENTITY->value, $generation->value);
+    }
+
+    public static function index(string $name): Metadata
+    {
+        return Metadata::with(self::INDEX->value, $name);
+    }
+
+    public static function indexUnique(string $name): Metadata
+    {
+        return Metadata::with(self::INDEX_UNIQUE->value, $name);
+    }
+
+    public static function length(int $length): Metadata
+    {
+        return Metadata::with(self::LENGTH->value, $length);
+    }
+
+    public static function precision(int $precision): Metadata
+    {
+        return Metadata::with(self::PRECISION->value, $precision);
+    }
+
+    public static function primaryKey(string $name = ''): Metadata
+    {
+        return Metadata::with(self::PRIMARY_KEY->value, $name);
+    }
+
+    public static function scale(int $scale): Metadata
+    {
+        return Metadata::with(self::SCALE->value, $scale);
+    }
+
+    public static function type(string $type): Metadata
+    {
+        return Metadata::with(self::TYPE->value, $type);
+    }
+}