X-Git-Url: https://git.jsancho.org/?p=datasette-pytables.git;a=blobdiff_plain;f=datasette_pytables%2F__init__.py;h=094710b517ee27d50dbd2341952b4144fa2d082e;hp=9b2061890d6fe0eb03e01a425f8d7eecabdda4b0;hb=3b77ff8064a87213d72b14c0f7acdd77c88c05c4;hpb=5a6c3f4c97b3d7e598cbca4d9dfe9602cbe3406b

diff --git a/datasette_pytables/__init__.py b/datasette_pytables/__init__.py
index 9b20618..094710b 100644
--- a/datasette_pytables/__init__.py
+++ b/datasette_pytables/__init__.py
@@ -1,3 +1,6 @@
+from collections import OrderedDict
+from moz_sql_parser import parse
+import re
 import tables
 
 _connector_type = 'pytables'
@@ -17,7 +20,7 @@ def inspect(path):
             'name': table._v_pathname,
             'columns': colnames,
             'primary_keys': [],
-            'count': table.nrows,
+            'count': int(table.nrows),
             'label_column': None,
             'hidden': False,
             'fts_table': None,
@@ -26,3 +29,159 @@ def inspect(path):
 
     h5file.close()
     return h5tables, views, _connector_type
+
+def _parse_sql(sql, params):
+    # Table name
+    sql = re.sub('(?i)from \[(.*)]', 'from "\g<1>"', sql)
+    # Params
+    for param in params:
+        sql = sql.replace(":" + param, param)
+
+    try:
+        parsed = parse(sql)
+    except:
+        # Propably it's a PyTables expression
+        for token in ['group by', 'order by', 'limit']:
+            res = re.search('(?i)where (.*)' + token, sql)
+            if res:
+                modified_sql = re.sub('(?i)where (.*)(' + token + ')', '\g<2>', sql)
+                parsed = parse(modified_sql)
+                parsed['where'] = res.group(1)
+                break
+
+    # Always a list of fields
+    if type(parsed['select']) is not list:
+        parsed['select'] = [parsed['select']]
+
+    return parsed
+
+_operators = {
+    'eq': '==',
+    'neq': '!=',
+    'gt': '>',
+    'gte': '>=',
+    'lt': '<',
+    'lte': '<=',
+    'and': '&',
+    'or': '|',
+}
+
+class Connection:
+    def __init__(self, path):
+        self.path = path
+        self.h5file = tables.open_file(path)
+
+    def execute(self, sql, params=None, truncate=False):
+        if params is None:
+            params = {}
+        rows = []
+        truncated = False
+        description = []
+
+        parsed_sql = _parse_sql(sql, params)
+        table = self.h5file.get_node(parsed_sql['from'])
+        table_rows = []
+        fields = parsed_sql['select']
+
+        query = ''
+        start = 0
+        end = table.nrows
+
+        # Use 'where' statement or get all the rows
+        def _cast_param(field, pname):
+            # Cast value to the column type
+            coltype = table.coltypes[field]
+            fcast = None
+            if coltype == 'string':
+                fcast = str
+            elif coltype.startswith('int'):
+                fcast = int
+            elif coltype.startswith('float'):
+                fcast = float
+            if fcast:
+                params[pname] = fcast(params[pname])
+
+        def _translate_where(where):
+            # Translate SQL to PyTables expression
+            expr = ''
+            operator = list(where)[0]
+
+            if operator in ['and', 'or']:
+                subexpr = ["({})".format(_translate_where(q)) for q in where[operator]]
+                expr = " {} ".format(_operators[operator]).join(subexpr)
+            elif where == {'eq': ['rowid', 'p0']}:
+                nonlocal start, end
+                start = int(params['p0'])
+                end = start + 1
+            else:
+                left, right = where[operator]
+                if left in params:
+                    _cast_param(right, left)
+                elif right in params:
+                    _cast_param(left, right)
+
+                expr = "{left} {operator} {right}".format(left=left, operator=_operators.get(operator, operator), right=right)
+
+            return expr
+
+        if 'where' in parsed_sql:
+            if type(parsed_sql['where']) is dict:
+                query = _translate_where(parsed_sql['where'])
+            else:
+                query = parsed_sql['where']
+
+        # Limit number of rows
+        if 'limit' in parsed_sql:
+            max_rows = int(parsed_sql['limit'])
+            if end - start > max_rows:
+                end = start + max_rows
+
+        # Execute query
+        if query:
+            table_rows = table.where(query, params, start, end)
+        else:
+            table_rows = table.iterrows(start, end)
+
+        # Prepare rows
+        if len(fields) == 1 and type(fields[0]['value']) is dict and \
+           fields[0]['value'].get('count') == '*':
+            rows.append(Row({'count(*)': int(table.nrows)}))
+        else:
+            for table_row in table_rows:
+                row = Row()
+                for field in fields:
+                    if field['value'] == 'rowid':
+                        row['rowid'] = int(table_row.nrow)
+                    elif field['value'] == '*':
+                        for col in table.colnames:
+                            value = table_row[col]
+                            if type(value) is bytes:
+                                value = value.decode('utf-8')
+                            row[col] = value
+                    else:
+                        row[field['value']] = table_row[field['value']]
+                rows.append(row)
+
+        # Prepare query description
+        for field in [f['value'] for f in fields]:
+            if field == '*':
+                for col in table.colnames:
+                    description.append((col,))
+            else:
+                description.append((field,))
+
+        # Return the rows
+        if truncate:
+            return rows, truncated, tuple(description)
+        else:
+            return rows
+
+class Row(OrderedDict):
+    def __getitem__(self, label):
+        if type(label) is int:
+            return super(OrderedDict, self).__getitem__(list(self.keys())[label])
+        else:
+            return super(OrderedDict, self).__getitem__(label)
+
+    def __iter__(self):
+        return self.values().__iter__()