{"id":707,"date":"2008-03-17T21:15:00","date_gmt":"2008-03-17T21:15:00","guid":{"rendered":"\/blogs\/bobb\/post\/Programming-Policy-Based-Management-with-SMO-Part-3-ExpressionNode-and-Policy.aspx"},"modified":"2013-01-04T01:49:56","modified_gmt":"2013-01-04T09:49:56","slug":"programming-policy-based-management-with-smo-part-3-expressionnode-and-policy","status":"publish","type":"post","link":"https:\/\/www.sqlskills.com\/blogs\/bobb\/programming-policy-based-management-with-smo-part-3-expressionnode-and-policy\/","title":{"rendered":"Programming Policy-Based Management with SMO – Part 3 – ExpressionNode and Policy"},"content":{"rendered":"

\nThis is part three of a series on programming policy-based management. The series starts here<\/a>.\n<\/p>\n

\nSo, to initialize my Condition's ExpressionNode I need more than just a string. It doesn't look like, at this time, every ExpressionNode CAN initialized with a string. But we can use the subclasses. The ones I need here are Operator, Attribute, and Function. I need: DatabaseMailEnabled (Attribute), Equals (Operator) and false (Function). BTW, ExpressionNodeFunction appears to be what you are programming when you use the "Advanced Functions" dialog in the SSMS Condition dialog.\n<\/p>\n

\nPutting one expression together first looks like this:\n<\/p>\n

\nExpressionNode exp1 = new ExpressionNodeOperator(OperatorType.EQ,
\n    new ExpressionNodeAttribute("DatabaseMailEnabled"),
\n    new ExpressionNodeFunction(ExpressionNodeFunction.Function.False)
\n    );\n<\/p>\n

\nNote that, unlike in SSMS, you don't need '@'<\/a> before the attribute name. But I need to specify both DatabaseMail and SqlMail. That's just a little more complex.\n<\/p>\n

\nExpressionNode exp1 = new ExpressionNodeOperator(OperatorType.EQ,
\n    new ExpressionNodeAttribute("DatabaseMailEnabled"),
\n    new ExpressionNodeFunction(ExpressionNodeFunction.Function.False)
\n    );
\nExpressionNode exp2 = new ExpressionNodeOperator(OperatorType.EQ,
\n    new ExpressionNodeAttribute("SqlMailEnabled"),
\n    new ExpressionNodeFunction(ExpressionNodeFunction.Function.False)
\n    );
\nExpressionNode exp_both = new ExpressionNodeOperator(OperatorType.AND, exp1, exp2);\n<\/p>\n

\ncon1.ExpressionNode = exp_both;
\ncon1.Create();\n<\/p>\n

\nAnd, nice as you please. Looks just like the one defined in SSMS using the GUI. Make sure that you remove (or comment out) the original ExpressionNode.Parse statement.\n<\/p>\n

\nNow, on to the policy.\n<\/p>\n

\n\/\/ Create a policy that uses the condition we just created
\nPolicy p1 = new Policy(ps, "OffByDefaultSMO");
\np1.Condition = "MailOffSMO";
\np1.AutomatedPolicyExecutionMode = AutomatedPolicyExecutionMode.None;
\np1.Enabled = false;
\np1.Create();\n<\/p>\n

\nLooks like the one created by the GUI and works like it too.\n<\/p>\n

\nThis is a pretty simple policy, because it can only be applied at the instance level. Next, we'll look at a policy that can be applied to a set of database objects, e.g. All tables in a particular database. This requires that we investigate ObjectSets.\n<\/p>\n

\nCavaet. It's pretty easy to make a mistake, sans docs. Some mistakes produce a generic "I can't do this"-type message. So ALWAYS drill into the INNER exception if you get an error. That is:\n<\/p>\n

\ntry
\n{
\n    con1.ExpressionNode = exp_both;
\n    con1.Create();
\n}
\ncatch (Exception ex)
\n{
\n    Console.WriteLine(ex.Message);
\n    if (ex.InnerException != null)
\n    {
\n        Console.WriteLine(ex.InnerException.Message);
\n    }
\n}\n<\/p>\n

\nStack trace might even be helpful.<\/p>\n","protected":false},"excerpt":{"rendered":"

This is part three of a series on programming policy-based management. The series starts here. So, to initialize my Condition's ExpressionNode I need more than just a string. It doesn't look like, at this time, every ExpressionNode CAN initialized with a string. But we can use the subclasses. The ones I need here are Operator, […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20,25,29],"tags":[],"class_list":["post-707","post","type-post","status-publish","format-standard","hentry","category-policy-based-management","category-smo","category-sql-server-2008"],"yoast_head":"\nProgramming Policy-Based Management with SMO - Part 3 - ExpressionNode and Policy - Bob Beauchemin<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.sqlskills.com\/blogs\/bobb\/programming-policy-based-management-with-smo-part-3-expressionnode-and-policy\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Programming Policy-Based Management with SMO - Part 3 - ExpressionNode and Policy - Bob Beauchemin\" \/>\n<meta property=\"og:description\" content=\"This is part three of a series on programming policy-based management. The series starts here. So, to initialize my Condition's ExpressionNode I need more than just a string. It doesn't look like, at this time, every ExpressionNode CAN initialized with a string. But we can use the subclasses. 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