datasette_pytables/__init__.py

   1 import tables
   2 import sqlparse
   3 from collections import OrderedDict
   4
   5 _connector_type = 'pytables'
   6
   7 def inspect(path):
   8     "Open file and return tables info"
   9     h5tables = {}
  10     views = []
  11     h5file = tables.open_file(path)
  12
  13     for table in filter(lambda node: not(isinstance(node, tables.group.Group)), h5file):
  14         colnames = []
  15         if isinstance(table, tables.table.Table):
  16             colnames = table.colnames
  17
  18         h5tables[table._v_pathname] = {
  19             'name': table._v_pathname,
  20             'columns': colnames,
  21             'primary_keys': [],
  22             'count': table.nrows,
  23             'label_column': None,
  24             'hidden': False,
  25             'fts_table': None,
  26             'foreign_keys': {'incoming': [], 'outgoing': []},
  27         }
  28
  29     h5file.close()
  30     return h5tables, views, _connector_type
  31
  32 def _parse_sql(sql):
  33     parsed = sqlparse.parse(sql)
  34     stmt = parsed[0]
  35     parsed_sql = {}
  36     current_keyword = ""
  37     for token in stmt.tokens:
  38         if token.is_keyword:
  39             if current_keyword in parsed_sql and parsed_sql[current_keyword] == '':
  40                 # Check composed keywords like 'order by'
  41                 del parsed_sql[current_keyword]
  42                 current_keyword += " " + str(token)
  43             else:
  44                 current_keyword = str(token)
  45             parsed_sql[current_keyword] = ""
  46         else:
  47             if not token.is_whitespace:
  48                 parsed_sql[current_keyword] += str(token)
  49     return parsed_sql
  50
  51 class Connection:
  52     def __init__(self, path):
  53         self.path = path
  54         self.h5file = tables.open_file(path)
  55
  56     def execute(self, sql, params=None, truncate=False):
  57         rows = []
  58         truncated = False
  59         description = []
  60
  61         parsed_sql = _parse_sql(sql)
  62         table = self.h5file.get_node(parsed_sql['from'][1:-1])
  63         table_rows = []
  64         fields = parsed_sql['select'].split(',')
  65
  66         # Use 'where' statement or get all the rows
  67         if 'where' in parsed_sql:
  68             pass
  69         else:
  70             table_rows = table.iterrows()
  71
  72         # Prepare rows
  73         if len(fields) == 1 and fields[0] == 'count(*)':
  74             rows.append(Row({fields[0]: table.nrows}))
  75         else:
  76             for table_row in table_rows:
  77                 row = Row()
  78                 for field in fields:
  79                     if field == 'rowid':
  80                         row[field] = table_row.nrow
  81                     elif field == '*':
  82                         for col in table.colnames:
  83                             row[col] = table_row[col]
  84                     else:
  85                         row[field] = table_row[field]
  86                 rows.append(row)
  87
  88         # Prepare query description
  89         for field in fields:
  90             if field == '*':
  91                 for col in table.colnames:
  92                     description.append((col,))
  93             else:
  94                 description.append((field,))
  95
  96         if truncate:
  97             return rows, truncated, tuple(description)
  98         else:
  99             return rows
 100
 101 class Row(OrderedDict):
 102     def __getitem__(self, label):
 103         if type(label) is int:
 104             return super(OrderedDict, self).__getitem__(list(self.keys())[label])
 105
 106     def __iter__(self):
 107         return self.values().__iter__()