Treasures of Cache 2010 Ian Cargill Development Manager Dendrite Clinical Systems

Before We Start Terminal Window Tricks ! To run an OS Shell command D $System.SQL.Shell() q(uit) to exit back to terminal

New Dynamic SQL (New in Caché 2010) This is based on the new %SQL.Statement and %SQL.StatementResult (and related) classes. %SQL.Statement - implements an interface to prepare and execute dynamic SQL statements. %SQL.StatementResult - Every dynamic statement execution returns a result object.

New Dynamic SQL Chapter in online Documents: "Using Dynamic SQL" Superficially similar to %ResultSet (%Prepare, %Execute, etc), but many additional features and advantages.

Can set DisplayMode as argument to %New More flexible Prepare of query (e.g. can pass multiline query as array!) %ExecDirect combines %Prepare and %Execute %Display method (for debug) %Print (with optional delimiter) - e.g. to produce CSV files but as Louise is doing an entire session on this - that is all I will say …

%SYSTEM.Encryption This class provides class functions to perform data encryption, Base64 encoding, hashing, and generation of message authentication codes. Some complex encryption support for experts, but a number of useful applications for the more humble programmer:

%SYSTEM.Encryption Encrypting passwords for storage –e.g. MD5Hash, SHA1Hash Encoding binary data for 'plain text' transmission. E.g. SOAP messages. –Base64Encode –Base64Decode

ClassMethod Base64ToFile(ByRef Data64 As %String, FileName As %Library.String) As %Library.String { Set res="OK" try { Set dat=##class(%SYSTEM.Encryption).Base64Decode(Data64) Set file=##class(%File).%New(FileName) Do file.Open("WN") Do file.Write(dat) Do file.Close() Kill file } catch { Set res=$ZError } Quit "OK“ }

GUIDs If a persistent class is marked as GUIDENABLED, Caché will assign Globally Unique IDentifiers (GUIDs) to each object when it is created. A later call to delete the object via %Delete on an object will no longer delete the GUID for that object. There is history in the GUID global in each namespace where a GUIDENABLED object has been created. Users are responsible for removing entries from ^OBJ.GUID that are no longer needed.

GUIDs Primarily for Synchronization. But can be other uses. ^OBJ.GUID(0, "B43096CB-D24E-4A79-9A3D-D998E56C6B78")=$lb("4","Guid.Test") "B810DCE6-5BE9-4CC7-8E37-38A281BA2B67")=$lb("5","Guid.Test") "FE3D D6-4E84-AD46-6E027506A6F9")=$lb("6","Guid.Test") ^OBJ.GUID(1, $lb("4","Guid.Test"))="B43096CB-D24E-4A79-9A3D-D998E56C6B78" $lb("5","Guid.Test"))="B810DCE6-5BE9-4CC7-8E37-38A281BA2B67" $lb("6","Guid.Test"))="FE3D D6-4E84-AD46-6E027506A6F9"

Class Guid.Test Extends %Persistent { Parameter GUIDENABLED = 1; Property Name As %Library.String [ SqlColumnNumber = 2 ]; Property GUID As %Library.String [ Calculated, SqlComputeCode = { SET {GUID}=##class(Guid.Test).GetGUID({ID})}, SqlComputed, SqlColumnNumber =3 ]; Method GUIDGet() As %Library.String { Set key=..GetGUID(..%Id()) } ClassMethod GetGUID(Id As %Library.String) As %Library.String { Set key=$lb(Id,"Guid.Test") Quit ^OBJ.GUID(1,key) } }

GUID Add three rows and SELECT * FROM Guid.Test gives: #IDNameGUID , A0429A7-C DB2-CCF11AB6BCB , C-D C-AD33-A90E31D , FB-AEF1-DBE6A6FD0662

Referential Integrity on ID field Post Meeting Update: After the meeting, I raised this with InterSystems, and it seems there IS a way to do it, but no-one knew!! You can’t use the Wizard, but write the FK by hand, and simply OMIT THE INDEX NAME from the final argument. I.e. ForeignKey FKey(FieldName) References Sample.Parent()

Referential Integrity on ID field Some parts of ObjectScript are definitely brain-damaged. One such is how you define Referential Integrity. Typical Database: e.g. SQL Server ADD CONSTRAINT FK_XX FOREIGN KEY (ORDERNUMBER) REFERENCES DBO.ORDERHEADER(ORDERNUMBER) >>TABLE(FIELD)

Referential Integrity You define RI in a child class as, say… ForeignKey FKey(FieldName) References Sample.Parent(IName) Where Iname is the name of an index in IndexName in the parent class. Question? What is the name of the index on the default ID field??

Referential Integrity Because ID doesn't have an explicit index, you CANNOT directly reference the Primary Key field of the parent!!! Only in Cach é !! There is, however, a workaround, based on the fact that you can index calculated fields. Try this …

Class Reference.Parent Extends %Persistent { Index IPKId On PKId [unique]; Property PKId As %Library.Integer [ Calculated, SqlColumnNumber = 2, SqlComputeCode = { SET {PKId}={id}}, SqlComputed ]; Method PKIdGet() As %Library.Integer [ CodeMode = expression ] {..%Id() } Property ThisProperty As %Library.String; Property ThatProperty As %Library.Integer; }

Class Reference.Child Extends %Persistent { Property MyParentId As %Library.Integer; ForeignKey FkParent(MyParentId) References Reference.Parent(IPKId); Property ThisProperty As %Library.String; Property ThatProperty As %Library.Integer; }

$ZOBJ Functions Replaced The $ZOBJ functions have been replaced with standard Cach é functions. The $ZOBJ functions are still available to applications, but they are no longer documented. The calling sequences for the replacement functions remain the same as before; a textual substitution is all that is required to update the application usage. The replacements are given in the following table:

Was Now use $ZOBJCLASSMETHOD$CLASSMETHOD $ZOBJMETHOD$METHOD $ZOBJPROPERTY$PROPERTY $ZOBJCLASS$CLASSNAME Note: The function, $ZOBJCLASS, was not documented in prior versions. $ZOBJ Functions Replaced

Old style Set oDat=$ZObjClassMethod(Class, "%New") Set oDat=$ZObjClassMethod(Class, "%OpenId", ObjId) Set CurrentVal=$ZOBJPROPERTY(oDat, FldName) Set $ZOBJPROPERTY(oDat, FldName)=NewValue

New Style Set oDat=$CLASSMETHOD(Class, "%New") Set oDat=$CLASSMETHOD(Class, "%OpenId", ObjId) Set CurrentVal=$PROPERTY(oDat, FldName) Set $PROPERTY(oDat, FldName)=NewValue

Private Classmethods Now Supported Cach é now supports private class methods. Private classmethods cannot be called from outside of the class (or a subclass). For backward compatibility, all class methods have been marked “ public ” so customer code will continue to work correctly. The descriptions of these methods have been altered to add the string, “ [Previously private] ”, to them. New private classmethods added to classes in the future will be inaccessible from outside the class.