func getTableMetadata()

in metadata.go [608:739]
114 lines of code
12 McCabe index (conditional complexity)

func getTableMetadata(session *Session, keyspaceName string) ([]TableMetadata, error) {

	var (
		iter *Iter
		scan func(iter *Iter, table *TableMetadata) bool
		stmt string

		keyAliasesJSON    []byte
		columnAliasesJSON []byte
	)

	if session.useSystemSchema { // Cassandra 3.x+
		stmt = `
		SELECT
			table_name
		FROM system_schema.tables
		WHERE keyspace_name = ?`

		switchIter := func() *Iter {
			iter.Close()
			stmt = `
				SELECT
					view_name
				FROM system_schema.views
				WHERE keyspace_name = ?`
			iter = session.control.query(stmt, keyspaceName)
			return iter
		}

		scan = func(iter *Iter, table *TableMetadata) bool {
			r := iter.Scan(
				&table.Name,
			)
			if !r {
				iter = switchIter()
				if iter != nil {
					switchIter = func() *Iter { return nil }
					r = iter.Scan(&table.Name)
				}
			}
			return r
		}
	} else if session.cfg.ProtoVersion == protoVersion1 {
		// we have key aliases
		stmt = `
		SELECT
			columnfamily_name,
			key_validator,
			comparator,
			default_validator,
			key_aliases,
			column_aliases,
			value_alias
		FROM system.schema_columnfamilies
		WHERE keyspace_name = ?`

		scan = func(iter *Iter, table *TableMetadata) bool {
			return iter.Scan(
				&table.Name,
				&table.KeyValidator,
				&table.Comparator,
				&table.DefaultValidator,
				&keyAliasesJSON,
				&columnAliasesJSON,
				&table.ValueAlias,
			)
		}
	} else {
		stmt = `
		SELECT
			columnfamily_name,
			key_validator,
			comparator,
			default_validator
		FROM system.schema_columnfamilies
		WHERE keyspace_name = ?`

		scan = func(iter *Iter, table *TableMetadata) bool {
			return iter.Scan(
				&table.Name,
				&table.KeyValidator,
				&table.Comparator,
				&table.DefaultValidator,
			)
		}
	}

	iter = session.control.query(stmt, keyspaceName)

	tables := []TableMetadata{}
	table := TableMetadata{Keyspace: keyspaceName}

	for scan(iter, &table) {
		var err error

		// decode the key aliases
		if keyAliasesJSON != nil {
			table.KeyAliases = []string{}
			err = json.Unmarshal(keyAliasesJSON, &table.KeyAliases)
			if err != nil {
				iter.Close()
				return nil, fmt.Errorf(
					"invalid JSON value '%s' as key_aliases for in table '%s': %v",
					keyAliasesJSON, table.Name, err,
				)
			}
		}

		// decode the column aliases
		if columnAliasesJSON != nil {
			table.ColumnAliases = []string{}
			err = json.Unmarshal(columnAliasesJSON, &table.ColumnAliases)
			if err != nil {
				iter.Close()
				return nil, fmt.Errorf(
					"invalid JSON value '%s' as column_aliases for in table '%s': %v",
					columnAliasesJSON, table.Name, err,
				)
			}
		}

		tables = append(tables, table)
		table = TableMetadata{Keyspace: keyspaceName}
	}

	err := iter.Close()
	if err != nil && err != ErrNotFound {
		return nil, fmt.Errorf("error querying table schema: %v", err)
	}

	return tables, nil
}