Find out the schema of a table.
This function uses introspection methods provided by the database to create a schema array. This is useful, for example, during update when the old schema is not available.
$table: Name of the table.
An array representing the schema, from drupal_get_schema().
protected function introspectSchema($table) {
$mapped_fields = array_flip($this
->getFieldTypeMap());
$schema = array(
'fields' => array(),
'primary key' => array(),
'unique keys' => array(),
'indexes' => array(),
);
$info = $this
->getPrefixInfo($table);
$result = $this->connection
->query('PRAGMA ' . $info['schema'] . '.table_info(' . $info['table'] . ')');
foreach ($result as $row) {
if (preg_match('/^([^(]+)\\((.*)\\)$/', $row->type, $matches)) {
$type = $matches[1];
$length = $matches[2];
}
else {
$type = $row->type;
$length = NULL;
}
if (isset($mapped_fields[$type])) {
list($type, $size) = explode(':', $mapped_fields[$type]);
$schema['fields'][$row->name] = array(
'type' => $type,
'size' => $size,
'not null' => !empty($row->notnull),
'default' => trim($row->dflt_value, "'"),
);
if ($length) {
$schema['fields'][$row->name]['length'] = $length;
}
if ($row->pk) {
$schema['primary key'][] = $row->name;
}
}
else {
new \Exception("Unable to parse the column type " . $row->type);
}
}
$indexes = array();
$result = $this->connection
->query('PRAGMA ' . $info['schema'] . '.index_list(' . $info['table'] . ')');
foreach ($result as $row) {
if (strpos($row->name, 'sqlite_autoindex_') !== 0) {
$indexes[] = array(
'schema_key' => $row->unique ? 'unique keys' : 'indexes',
'name' => $row->name,
);
}
}
foreach ($indexes as $index) {
$name = $index['name'];
// Get index name without prefix.
$index_name = substr($name, strlen($info['table']) + 1);
$result = $this->connection
->query('PRAGMA ' . $info['schema'] . '.index_info(' . $name . ')');
foreach ($result as $row) {
$schema[$index['schema_key']][$index_name][] = $row->name;
}
}
return $schema;
}