Add set_column(s) for ovs_idl backend

The create/set Commands allow one to pass the result of txn.add()
to a subsequent Command in a transaction to use the result of that
Command's execution. In this way one can create a DHCP Option and
then pass it to an lsp_add() command.

This change replaces the direct uses of setattr() with a version
that does the substituation if one of the arguments is a Command
instead of a normal value, enabling this behavior for all Commands.

Change-Id: I97e7cbff7e71f7e1f00342c724af963a411b6c5d

ovsdbapp/backend/ovs_idl/command.py

@@ -40,6 +40,15 @@ class BaseCommand(api.Command):
             if check_error:
                 raise
 
+    @classmethod
+    def set_column(cls, row, col, val):
+        setattr(row, col, idlutils.db_replace_record(val))
+
+    @classmethod
+    def set_columns(cls, row, **columns):
+        for col, val in columns.items():
+            cls.set_column(row, col, val)
+
     def post_commit(self, txn):
         pass
 
@@ -70,8 +79,7 @@ class DbCreateCommand(BaseCommand):
 
     def run_idl(self, txn):
         row = txn.insert(self.api._tables[self.table])
-        for col, val in self.columns.items():
-            setattr(row, col, idlutils.db_replace_record(val))
+        self.set_columns(row, **self.columns)
         # This is a temporary row to be used within the transaction
         self.result = row
 
@@ -112,7 +120,7 @@ class DbSetCommand(BaseCommand):
                 existing = getattr(record, col, {})
                 existing.update(val)
                 val = existing
-            setattr(record, col, idlutils.db_replace_record(val))
+            self.set_column(record, col, val)
 
 
 class DbAddCommand(BaseCommand):
@@ -146,7 +154,7 @@ class DbAddCommand(BaseCommand):
                     field = getattr(record, self.column, [])
                     field.append(value)
             record.verify(self.column)
-            setattr(record, self.column, idlutils.db_replace_record(field))
+            self.set_column(record, self.column, field)
 
 
 class DbClearCommand(BaseCommand):

ovsdbapp/schema/ovn_northbound/commands.py

@@ -49,8 +49,7 @@ class LsAddCommand(cmd.AddCommand):
         else:
             # because ovs.db.idl brokenly requires a changed column
             sw.name = ""
-        for col, value in self.columns.items():
-            setattr(sw, col, value)
+        self.set_columns(sw, **self.columns)
         self.result = sw.uuid
 
 
@@ -172,7 +171,7 @@ class LspAddCommand(cmd.AddCommand):
         if tag and not 0 <= tag <= 4095:
             raise TypeError("tag must be 0 to 4095, inclusive")
         if (parent_name is None) != (tag is None):
-            raise TypeError("parent and tag must be passed together")
+            raise TypeError("parent_name and tag must be passed together")
         super(LspAddCommand, self).__init__(api)
         self.switch = switch
         self.port = port
@@ -215,8 +214,7 @@ class LspAddCommand(cmd.AddCommand):
             lsp.parent_name = self.parent
             lsp.tag_request = self.tag
         ls.addvalue('ports', lsp)
-        for col, value in self.columns.items():
-            setattr(lsp, col, value)
+        self.set_columns(lsp, **self.columns)
         self.result = lsp.uuid
 
 
@@ -519,8 +517,7 @@ class LrAddCommand(cmd.BaseCommand):
                 pass
         lr = txn.insert(self.api.tables['Logical_Router'])
         lr.name = self.router if self.router else ""
-        for col, value in self.columns.items():
-            setattr(lr, col, value)
+        self.set_columns(lr, **self.columns)
         self.result = lr.uuid
 
     def post_commit(self, txn):
@@ -596,8 +593,7 @@ class LrpAddCommand(cmd.BaseCommand):
         if self.peer:
             lrp.peer = self.peer
         lr.addvalue('ports', lrp)
-        for col, value in self.columns.items():
-            setattr(lrp, col, value)
+        self.set_columns(lrp, **self.columns)
         self.result = lrp.uuid
 
     def post_commit(self, txn):
@@ -861,9 +857,7 @@ class LbAddCommand(cmd.BaseCommand):
             lb.name = self.lb
             lb.protocol = self.protocol
             lb.vips = {self.vip: self.ips}
-        for col, val in self.columns.items():
-            setattr(lb, col, val)
-
+        self.set_columns(lb, **self.columns)
         self.result = lb.uuid
 
     def post_commit(self, txn):