datasette_pytables/__init__.py

   1 from collections import OrderedDict
   2 from moz_sql_parser import parse
   3 import re
   4 import tables
   5
   6 _connector_type = 'pytables'
   7
   8 def inspect(path):
   9     "Open file and return tables info"
  10     h5tables = {}
  11     views = []
  12     h5file = tables.open_file(path)
  13
  14     for table in filter(lambda node: not(isinstance(node, tables.group.Group)), h5file):
  15         colnames = []
  16         if isinstance(table, tables.table.Table):
  17             colnames = table.colnames
  18
  19         h5tables[table._v_pathname] = {
  20             'name': table._v_pathname,
  21             'columns': colnames,
  22             'primary_keys': [],
  23             'count': int(table.nrows),
  24             'label_column': None,
  25             'hidden': False,
  26             'fts_table': None,
  27             'foreign_keys': {'incoming': [], 'outgoing': []},
  28         }
  29
  30     h5file.close()
  31     return h5tables, views, _connector_type
  32
  33 def _parse_sql(sql, params):
  34     # Table name
  35     sql = re.sub('(?i)from \[(.*)]', 'from "\g<1>"', sql)
  36     # Params
  37     for param in params:
  38         sql = sql.replace(":" + param, param)
  39
  40     try:
  41         parsed = parse(sql)
  42     except:
  43         # Propably it's a PyTables expression
  44         for token in ['group by', 'order by', 'limit', '']:
  45             res = re.search('(?i)where (.*)' + token, sql)
  46             if res:
  47                 modified_sql = re.sub('(?i)where (.*)(' + token + ')', '\g<2>', sql)
  48                 parsed = parse(modified_sql)
  49                 parsed['where'] = res.group(1).strip()
  50                 break
  51
  52     # Always a list of fields
  53     if type(parsed['select']) is not list:
  54         parsed['select'] = [parsed['select']]
  55
  56     return parsed
  57
  58 _operators = {
  59     'eq': '==',
  60     'neq': '!=',
  61     'gt': '>',
  62     'gte': '>=',
  63     'lt': '<',
  64     'lte': '<=',
  65     'and': '&',
  66     'or': '|',
  67 }
  68
  69 class Connection:
  70     def __init__(self, path):
  71         self.path = path
  72         self.h5file = tables.open_file(path)
  73
  74     def execute(self, sql, params=None, truncate=False, page_size=None):
  75         if params is None:
  76             params = {}
  77         rows = []
  78         truncated = False
  79         description = []
  80
  81         parsed_sql = _parse_sql(sql, params)
  82
  83         if parsed_sql['from'] == 'sqlite_master':
  84             return self._execute_datasette_query(sql, params)
  85
  86         table = self.h5file.get_node(parsed_sql['from'])
  87         table_rows = []
  88         fields = parsed_sql['select']
  89
  90         query = ''
  91         start = 0
  92         end = table.nrows
  93
  94         # Use 'where' statement or get all the rows
  95         def _cast_param(field, pname):
  96             # Cast value to the column type
  97             coltype = table.coltypes[field]
  98             fcast = None
  99             if coltype == 'string':
 100                 fcast = str
 101             elif coltype.startswith('int'):
 102                 fcast = int
 103             elif coltype.startswith('float'):
 104                 fcast = float
 105             if fcast:
 106                 params[pname] = fcast(params[pname])
 107
 108         def _translate_where(where):
 109             # Translate SQL to PyTables expression
 110             expr = ''
 111             operator = list(where)[0]
 112
 113             if operator in ['and', 'or']:
 114                 subexpr = [_translate_where(e) for e in where[operator]]
 115                 subexpr = filter(lambda e: e, subexpr)
 116                 subexpr = ["({})".format(e) for e in subexpr]
 117                 expr = " {} ".format(_operators[operator]).join(subexpr)
 118             elif operator == 'exists':
 119                 pass
 120             elif where == {'eq': ['rowid', 'p0']}:
 121                 nonlocal start, end
 122                 start = int(params['p0'])
 123                 end = start + 1
 124             else:
 125                 left, right = where[operator]
 126                 if left in params:
 127                     _cast_param(right, left)
 128                 elif right in params:
 129                     _cast_param(left, right)
 130
 131                 expr = "{left} {operator} {right}".format(left=left, operator=_operators.get(operator, operator), right=right)
 132
 133             return expr
 134
 135         if 'where' in parsed_sql:
 136             if type(parsed_sql['where']) is dict:
 137                 query = _translate_where(parsed_sql['where'])
 138             else:
 139                 query = parsed_sql['where']
 140
 141         # Limit number of rows
 142         if 'limit' in parsed_sql:
 143             max_rows = int(parsed_sql['limit'])
 144             if end - start > max_rows:
 145                 end = start + max_rows
 146
 147         # Truncate if needed
 148         if page_size and truncate:
 149             if end - start > page_size:
 150                 end = start + page_size
 151                 truncated = True
 152
 153         # Execute query
 154         if query:
 155             table_rows = table.where(query, params, start, end)
 156         else:
 157             table_rows = table.iterrows(start, end)
 158
 159         # Prepare rows
 160         if len(fields) == 1 and type(fields[0]['value']) is dict and \
 161            fields[0]['value'].get('count') == '*':
 162             rows.append(Row({'count(*)': int(table.nrows)}))
 163         else:
 164             if type(table) is tables.table.Table:
 165                 for table_row in table_rows:
 166                     row = Row()
 167                     for field in fields:
 168                         field_name = field['value']
 169                         if type(field_name) is dict and 'distinct' in field_name:
 170                             field_name = field_name['distinct']
 171                         if field_name == 'rowid':
 172                             row['rowid'] = int(table_row.nrow)
 173                         elif field_name == '*':
 174                             for col in table.colnames:
 175                                 value = table_row[col]
 176                                 if type(value) is bytes:
 177                                     value = value.decode('utf-8')
 178                                 row[col] = value
 179                         else:
 180                             row[field_name] = table_row[field_name]
 181                     rows.append(row)
 182             else:
 183                 # Any kind of array
 184                 rowid = start - 1
 185                 for table_row in table_rows:
 186                     row = Row()
 187                     rowid += 1
 188                     for field in fields:
 189                         field_name = field['value']
 190                         if type(field_name) is dict and 'distinct' in field_name:
 191                             field_name = field_name['distinct']
 192                         if field_name == 'rowid':
 193                             row['rowid'] = rowid
 194                         else:
 195                             value = table_row
 196                             if type(value) is bytes:
 197                                 value = value.decode('utf-8')
 198                             row['value'] = value
 199                     rows.append(row)
 200
 201         # Prepare query description
 202         for field in [f['value'] for f in fields]:
 203             if field == '*':
 204                 if type(table) is tables.table.Table:
 205                     for col in table.colnames:
 206                         description.append((col,))
 207                 else:
 208                     description.append(('value',))
 209             else:
 210                 description.append((field,))
 211
 212         # Return the rows
 213         if truncate:
 214             return rows, truncated, tuple(description)
 215         else:
 216             return rows
 217
 218     def _execute_datasette_query(self, sql, params):
 219         "Datasette special queries for getting tables info"
 220         if sql == "SELECT count(*) from sqlite_master WHERE type = 'view' and name=:n":
 221             row = Row()
 222             row['count(*)'] = 0
 223             return [row]
 224         elif sql == 'select sql from sqlite_master where name = :n and type="table"':
 225             try:
 226                 table = self.h5file.get_node(params['n'])
 227                 row = Row()
 228                 row['sql'] = 'CREATE TABLE {} ()'.format(params['n'])
 229                 return [row]
 230             except:
 231                 return []
 232         else:
 233             raise Exception("SQLite queries cannot be executed with this connector")
 234
 235 class Row(list):
 236     def __init__(self, values=None):
 237         self.labels = []
 238         self.values = []
 239         if values:
 240             for idx in values:
 241                 self.__setitem__(idx, values[idx])
 242
 243     def __setitem__(self, idx, value):
 244         if type(idx) is str:
 245             if idx in self.labels:
 246                 self.values[self.labels.index(idx)] = value
 247             else:
 248                 self.labels.append(idx)
 249                 self.values.append(value)
 250         else:
 251             self.values[idx] = value
 252
 253     def __getitem__(self, idx):
 254         if type(idx) is str:
 255             return self.values[self.labels.index(idx)]
 256         else:
 257             return self.values[idx]
 258
 259     def __iter__(self):
 260         return self.values.__iter__()