Initial checkin of new API implementation

[plcapi.git] / PLC / Table.py

diff --git a/PLC/Table.py b/PLC/Table.py
new file mode 100644 (file)
index 0000000..3505d41
--- /dev/null
+++ b/PLC/Table.py
@@ -0,0 +1,90 @@
+class Row(dict):
+    """
+    Representation of a row in a database table. To use, optionally
+    instantiate with a dict of values. Update as you would a
+    dict. Commit to the database with flush().
+    """
+
+    # Set this to a dict of the valid columns in this table. If a column
+    # name ends in 's' and the column value is set by referring to the
+    # column without the 's', it is assumed that the column values
+    # should be aggregated into lists. For example, if fields contains
+    # the column 'role_ids' and row['role_id'] is set repeatedly to
+    # different values, row['role_ids'] will contain a list of the set
+    # values.
+    fields = {}
+
+    # These fields are derived from join tables and are not actually
+    # in the sites table.
+    join_fields = {}
+
+    # These fields are derived from join tables and are not returned
+    # by default unless specified.
+    extra_fields = {}
+
+    def __init__(self, fields):
+        self.update(fields)
+        
+    def update(self, fields):
+        for key, value in fields.iteritems():
+            self.__setitem__(key, value)
+
+    def __setitem__(self, key, value):
+        """
+        Magically takes care of aggregating certain variables into
+        lists.
+        """
+
+        # All known keys
+        all_fields = self.fields.keys() + \
+                     self.join_fields.keys() + \
+                     self.extra_fields.keys()
+
+        # Aggregate into lists
+        if (key + 's') in all_fields:
+            key += 's'
+            try:
+                if value not in self[key] and value is not None:
+                    self[key].append(value)
+            except KeyError:
+                if value is None:
+                    self[key] = []
+                else:
+                    self[key] = [value]
+            return
+
+        elif key in all_fields:
+            dict.__setitem__(self, key, value)
+
+    def validate(self):
+        """
+        Validates values. Will validate a value with a custom function
+        if a function named 'validate_[key]' exists.
+        """
+
+        # Validate values before committing
+        # XXX Also truncate strings that are too long
+        for key, value in self.iteritems():
+            if value is not None and hasattr(self, 'validate_' + key):
+                validate = getattr(self, 'validate_' + key)
+                self[key] = validate(value)
+
+    def flush(self, commit = True):
+        """
+        Flush changes back to the database.
+        """
+
+        pass
+
+class Table(dict):
+    """
+    Representation of row(s) in a database table.
+    """
+
+    def flush(self, commit = True):
+        """
+        Flush changes back to the database.
+        """
+
+        for row in self.values():
+            row.flush(commit)