#ObjectScript

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InterSystems ObjectScript is a scripting language to operate with data using any data model of InterSystems Data Platform (Objects, Relational, Key-Value, Document, Globals) and to develop business logic for serverside applications on InterSystems Data Platform.

Documentation.

Question Jorge Torres · Jun 7, 2017

Hello experts,

I’m working on an "Sort After" (]]) bug that I traced back to some weird behavior in ObjectScript.  Perhaps someone can enlighten me…

The problem is as follows:

Let’s say we have:

Set A = “1.0”
Set B = “2.2”

If you execute the command ‘Sort After’ (]]), you get the following:

W A]]B
​1

…Which is wrong, A does NOT sort after B.  The output should be 0.

If you set A and B to numeric values, it correctly outputs false (0):

set A = 1.0
set B = 2.2
​W A]]B

0

I dug for a bit, and came up with this:   If you set  a numeric string to “<number>.

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Article Sean Connelly · Jun 7, 2017 1m read

The Cogs.JsonClass library is now available in the Cogs project on GitHub.

https://github.com/SeanConnelly/Cogs

Please see the README and the /docs folder on how to use the class.

Overview

The Cogs.JsonClass class provides a one step serialisation and deserialisation to and from Caché registered and persistent classes. It is not dependent on any other code and should be compatible with older versions of Caché.

The unit tests have been included in the update, but until I release the dependent Touchstone unit test solution it won't be possible to run these tests.

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Question P Patz · Jun 1, 2017

I need to guarantee that a parent AND child rows has been inserted successfully before any other process is able to read ANY of the data.

What is the proper way to prevent DIRTY reads?  Per the InterSystems's documentation I should be able to use ' START TRANSACTION ISOLATION LEVEL READ COMMITTED'.  I have attempted to use these commands in embedded and dynamic SQL calls to no avail.

I have to be able to insert the data via JDBC calls, but legacy Caché (.MAC) may be reading the data, and if the data is read to quickly, I could have processing errors, as all the child rows have not been inserted.

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Question Evgeny Shvarov · May 26, 2017

Hi!

I'm saving object instance using RestForms.

RESTFormsUI calls %Save() for me, which is great. But I want to set the property CreationDate with the current date for every new record being inserted.

So  object callback implementation seems as a reasonable option. I did the following:

Method %OnBeforeSave(insert as %Boolean) As %Status [ Private, ServerOnly = 1 ] 
{

 if insert s ..CreationDate=$H

 q $$$OK

}

And it works fine.

But Documentation says I'd better use %OnAddToSaveSet()

What are you using for the callbacks in similar cases?

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Article Vitaliy Serdtsev · May 20, 2017 10m read

This is a translation of the following article. Thanks @Evgeny Shvarov  for the help in translation.

Let's assume that you wrote a program that shows "Hello World!", for example:

  write "Hello, World!"

The program works and everyone is happy.

With time, however, your program becomes more complex, gets more features and you eventually need to show the same string in different languages. Moreover you don't know the number and names of these languages.

The spoiler below contains a description of how the task of multi-language localization is solved in Caché.

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Question P Patz · May 12, 2017

Looking for a way in which I could possibly pass a flag through a property when performing an Insert statement, on a mapped class.

insert into my.class (serialNumber, modelNumber, myFlag) value ('testSerial', 'testModel', 0)
    myFlag is not stored in the DB.

The mapped class then calls a legacy routine (MAC) via CodeMode = 'objectgenerator', (Insert method within the 'objectgenerator')

Within the legacy routine, I am setting an index... but I don't always want to set it (multiple inserts, and I will only set the index on the LAST insert)

How can I pass that flag through the insert

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Question Alexander Grishkan · May 9, 2017

What is a correct way to pass parameters to the  %CONTAINS in embedded SQL statement when searching thru %Text property?

s sp="child,health"

&SQL(

DECLARE c1 CURSOR FOR

SELECT ID INTO :id FROM ICD WHERE Name %CONTAINS (:sp)

...

is not the same as executing the following in the SQL Manager

SELECT ID FROM ICD WHERE Name %CONTAINS ('child','health')

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Article Pravin Barton · Apr 26, 2017 1m read

Say you have a global in one database that you instead want to map from a different database. If you just create a global mapping to the new database, the existing global will become inaccessible because it still lives on the old database. The documentation notes this problem here but doesn't give details on how to fix it.


When you create the global mapping you need to explicitly move the existing global to the new database. This is possible using the merge command along with extended global reference.

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Article Sean Connelly · Apr 13, 2017 3m read

On the back of my recent post on writing bug-less code I wanted to raise a few suggestions (to ISC) that would help prevent certain types of bugs at compile time. I've probably missed a few, but these are the main ones in my mind. Please contribute more suggestions.

Btw, these also serve as potential gotchas for new COS developers.

I except that introducing these types of changes can cause legacy code problems. Particularly where developers do some interesting overloading of method arguments.

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Question Arto Alatalo · Apr 11, 2017

I have classes A and B, B derived from A, A has method Abc.

From INT of class B I see that compiler copies implementation of Abc to class B, so that Abc exists both in A and B.

As result, when B invokes Abs, B.Abs() is executed instead of A.Abs(). In result debuger is not able to step into Abs and breakpoints in A.Abs never hit.

Why this happens and how can I avoid this?

Update:

OK, now I know the reason: compiler makes the copy if Abc has this line:

cn=##Expression($$$quote(%classname))

hmmmm.

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Question Scott Roth · Apr 11, 2017

With help from others here I had developed some code to take a Base64 PDF within a OBX.5 and save it locally to the file structure on the server.

I had to make a change to the code to return me a String so I can pass the Path back into Ensemble to use it in the message. When I made this change I am getting " ERROR #5034: Invalid status code structure ("/ensemble/data/transfer/AncillaryPDF/TMSAUDIO/Apr-11-1/980512729TMSAUDIO1046784936436537800.pdf")"

Here is the code...

ClassMethod DecodeBase64HL7ToFile(base64 As %Strea
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Question Massimo Sebastiani · Mar 30, 2017

Hello, we have a few hundreds of triggers to port from Oracle to Cachè for a migration project, and many of them have to change (for example, normalize a value, null it, etc) the value which is being inserted.

The documentation says "You cannot set {fieldname*N} in trigger code." , so we're unlucky.

Is there a good workaround for this ?

SqlComputeOnChange doesn't seem the best way, but I'm not totally sure: for example normalization and validation could have a better place somewhere else than a trigger.

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Question John Flippance · Mar 29, 2017

Hello,

We are working on creating a metadata file to accompany PDF documents produced by one of our third party systems for ingestion into our DMS.  One of the pieces of data that the metadata file must contain is the number of pages of the PDF document.

In Cache ObjectScript does anybody know if there is currently a way of counting the number of pages within a file (specifically a PDF) without invoking a non-Caché ObjectScript program/function from within Caché ObjectScript?

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