%ZEN.ObjectProjection demonstrates a few answers to your second question. There are probably more differences/advantages, but here are a few:

  • Projections can call methods of the class that was just compiled, while generator methods can't call methods of the class that's being compiled. Example: %ZEN.ObjectProjection calls the %GetIncludeInfo method of each class that was compiled.
  • Projections can avoid repeated work by queuing classes in CreateProjection and using the EndCompile method (as %ZEN.ObjectProjection does). In the case of the generated JS and CSS files for Zen, multiple classes may contribute content to the same file, so the file must be regenerated when any of these classes is compiled. If many such classes are compiled at the same time, the projection only regenerates each impacted file once. I don't think there's a good way to do the same thing in a generator method.

Eduard,

It would help if there was further explanation of your use case. What is the "additional check" in question? Is it a flag on the user at the application level? Is it a call to some other system?

For simplicity, let's suppose your application has a role called TerminalUser that has the %Service_Console:U permission, and that it's the only role an application user might have that grants that permission.

If the "additional check" is based on a flag in your application, your application could simply add/remove the TerminalUser role when that flag changes. See class documentation for Security.* in the %SYS namespace. This might rely on a "privileged routine application" to escalate roles if the user changing this flag wouldn't normally have the necessary privileges to change security settings.

In either case, ZAUTHENTICATE might still work, although it wouldn't be as elegant. It could perform whatever additional checks are needed (against your application or some external system), and possibly add or remove the TerminalUser role based on the results. ZAUTHENTICATE would always return an error, so it falls back to password login. At that point the user could authenticate successfully but might not be allowed to use terminal if the TerminalUser role was removed. (I haven't tried this, but it seems like it could work.)

If you're using OS or Kerberos authentication, ZAUTHORIZE could also be relevant.

Specifics on %CSP.Page / cspbind error handling:

There are alternatives to modifying system-level error message translations. Even if the localization is changed, the end user would probably still see "SQLCODE -139," which isn't helpful. What you probably want to show the user is "Someone else has modified this record. Please reload the page and try again." or something similar.

Using %CSP.Page and a form with cspbind, there's no way to customize the error handling in the generated <form name>_save function. It seems to always show any error message in an alert. An alternative would be to use a similar approach to form.csp and formsubmit.csp in the SAMPLES namespace, submitting the form and calling the <form name>Submit method of the page rather than using a hyperevent (in form_save()). Note that you don't need a separate page to handle the form submit; one page can do it all.

Of course, if the form is saved with a POST rather than a hyperevent, and optimistic concurrency control is in use, it might be worth a separate call to the server immediately before submitting the form for an optimistic concurrency check. If someone else edited the record, the page could tell the user rather than submitting the form. This wouldn't prevent the error in question, but would at least make it much less likely.

(Side note: %CSP.Page/cspbind is very old technology. There are better tools available now, but if you're stuck with it in a large existing project, that's understandable.)

 

General thoughts on showing users friendly error messages:

The more general problem is: "Often, the error codes and messages the system produces are not helpful to an end user. How do you show the user the information they need when an error occurs?"

This gets more complicated because error messages can come from very different sources - for example, SQL, an object %Save, a variable being undefined, or the application detecting a user error.

The standard for the large Caché-based application I work on is:

  • Within UI classes (class-based CSP or Zen, in our case), server-side code is wrapped in try-catch blocks.
  • Different types of exceptions (subclasses of %Exception.AbstractException) are thrown for the different types of errors that occur. These may be:
    • SQLCODEs and associated messages from embedded or dynamic SQL
    • Error %Status codes from object %Saves and various other things
    • General internal errors in application business logic
    • User errors detected in business logic. (These are treated differently for logging purposes; user errors may be more common than system errors and might not be logged.)
    • System errors (<UNDEFINED>, <SUBSCRIPT>, etc.)
  • Any of these types of exceptions. except system errors, may include a user-friendly message explaining what went wrong.
  • If an exception is caught, a method is called to (1) log that an error occurred and (2) either provide a description of the error that the user can understand, or else just say that an error happened (with the confusing details omitted, although they are logged).
    • If the exception already has a friendly message for the user, it's returned.
    • Otherwise, for error SQLCODEs and error %Status codes, we provide general messages for concurrency-related errors and some other common error codes. We also have a system for interpreting foreign and unique key violations (from an SQLCODE or %Status) and providing more descriptive messages based on those.
    • Worst case, the message "An internal error occurred (log ID _____)" is returned.
  • The message is shown to the user in red text, an alert dialog (ideally not a vanilla JavaScript alert), or however else makes sense in context.
  • There are macros for the different types of exceptions and for getting the user-friendly message, for ease of maintainability.

This has been bothering me a little bit; %Dictionary.* should really be a last-resort option, in my opinion, and it isn't easy to use it to get the full picture from an SQL perspective.

Here are some alternative/possibly-better solutions, using %SQL.StatementMetadata and INFORMATION_SCHEMA. It looks like INFORMATION_SCHEMA is more exactly what you were looking for, if you're running on a recent enough Caché version (2015.1+). I haven't been able to find documentation on it other than the class reference, though.

/// NOTE: It could be good to validate pTableName to avoid SQL injection. (Outside the scope of this demo.)
/// This works pre-2015.1 (since %SQL.Statement was introduced - maybe 2012.2+?)
ClassMethod GetTableColumns(pTableName As %String) As %List
{
    #dim tResult As %SQL.StatementResult
    #dim tMetadata As %SQL.StatementMetadata
    Set tStmt = ##class(%SQL.Statement).%New()
    $$$ThrowOnError(tStmt.%Prepare("select top 0 * from "_pTableName))
    Set tResult = tStmt.%Execute(), tMetadata = tResult.%GetMetadata()
    Set tCols = ""
    For i=1:1:tMetadata.columnCount {
        Set tCols = tCols_$ListBuild(tMetadata.columns.GetAt(i).colName)
    }
    Quit tCols
}

/// This will only work on 2015.1+; INFORMATION_SCHEMA is a new feature. For more information, see the class reference for it in the documentation.
ClassMethod GetTableColumnsNew(pTableName As %String) As %List
{
    #dim tResult As %SQL.StatementResult
    Set tStmt = ##class(%SQL.Statement).%New()
    Set tSchema = $Piece(pTableName,".")
    Set tTableName = $Piece(pTableName,".",2)
    $$$ThrowOnError(tStmt.%Prepare("select COLUMN_NAME from INFORMATION_SCHEMA.COLUMNS where TABLE_SCHEMA = ? and TABLE_NAME = ?"))
    Set tResult = tStmt.%Execute(tSchema,tTableName)
    Set tCols = ""
    While tResult.%Next(.tSC) {
        Set tCols = tCols_$ListBuild(tResult.%Get("COLUMN_NAME"))
    }
    $$$ThrowOnError(tSC)
    Quit tCols
}

Using this:

SAMPLES>set cols = ##class(Demo.TableColumns).GetTableColumns("Sample.Person")
SAMPLES>w $lts(cols)
ID,Age,DOB,FavoriteColors,Name,SSN,Spouse,Home_City,Home_State,Home_Street,Home_Zip,Office_City,Office_State,Office_Street,Office_Zip
SAMPLES>set cols = ##class(Demo.TableColumns).GetTableColumnsNew("Sample.Person")
SAMPLES>w $lts(cols)                                                            ID,Age,DOB,FavoriteColors,Name,SSN,Spouse,Home_City,Home_State,Home_Street,Home_Zip,Office_City,Office_State,Office_Street,Office_Zip

In various posts, you've talked about having an implementation tool that is run from the browser, and you've also talked about running it from terminal. Here's a design that would be well-suited to both:

* Settings that apply to the whole thing are properties of an object (class extends %RegisteredObject)

* There's a class method (static method in other languages) to get the settings' values interactively

* There's an instance method to run the setup on an instance of the class

Include %syPrompt

Class Demo.SetupTool Extends %RegisteredObject
{

Property Type As %String(VALUELIST = ",Gateway,IHE");

Property Setting1Value As %String [ InitialExpression = "ABC" ];

Property Setting2Value As %Boolean [ InitialExpression = ];

ClassMethod RunInteractive()
{
    Set tSettingsObject = ..%New()
    
    Write "Deployment Utility"
    Set options(1) = "Gateway"
    Set options(2) = "IHE"
    Do ##class(%Prompt).GetArray("Deployment Type?",.tType,.options,,,,$$$InitialDisplayMask+$$$MatchArrayMask)
    Set tSettingsObject.Type = tType
    
    Set tString = tSettingsObject.Setting1Value
    Do ##class(%Prompt).GetString("Enter a string: ",.tString)
    Set tSettingsObject.Setting1Value = tString
    
    Set tYesOrNo = tSettingsObject.Setting2Value
    Do ##class(%Prompt).GetYesNo("Is this a helpful demo? ",.tYesOrNo)
    Set tSettingsObject.Setting2Value = tYesOrNo
    
    Do tSettingsObject.DoSetup()
}

Method DoSetup()
{
    Write !,"Starting ",..Type," deployment...",!
    // Here, do things based on properties of this object.
    If '..Setting2Value {
        //Do something specific if Setting2Value is false.
        Write "Why not?",!
    }
}

}
 

Then, for example:

USER>d ##class(Demo.SetupTool).RunInteractive()
Deployment Utility
 
1) Gateway
2) IHE
 
Deployment Type? 1 Gateway
Enter a string:  ABC =>
Is this a helpful demo?  Yes => No
Starting Gateway deployment...
Why not?

 

Or, if you want to do the same kind of setup from a simple ZenMethod in a Zen page or something, you could set up a settings object and then call DoSetup() on it.

USER>set tSettings = ##class(Demo.SetupTool).%New()
 
USER>set tSettings.Type = "IHE"
 
USER>d tSettings.DoSetup()
 
Starting IHE deployment...

Here's some relevant documentation: http://docs.intersystems.com/cache20152/csp/docbook/DocBook.UI.Page.cls?KEY=GORIENT_ch_cos#GORIENT_cos_scope

One way to make this work as-is would be to put tstVar in the "public" list:

start
    set tstVar = "Green"
    do TestIt()
 
TestIt() [tstVar] {
    write tstVar 
}

Another would be to give the variable a name starting with a %:

start
    set %tstVar = "Green"
    do TestIt()
 
TestIt() {
    write %tstVar 
}

"GOTO label" jumps to a specified label in the same context frame.

"DO label" adds a new context frame. Code at the specified label will execute until a QUIT/RETURN or the end of the routine, then execution will resume at the next line after the DO command.

So in this case it's running through the whole routine (including everything under the dataentry label, with dtype already set to something valid), including printing the message at the end. Then it proceeds to the next thing after the DO command, which is printing that line again.

For what it's worth, if you're building command-line tools, %Library.Prompt may save you a lot of time. See the class reference for more informatioan.

For example:

#include %syPrompt
    New options,dtype
    Write "Deployment Utility"
    Set options(1) = "Gateway"
    Set options(2) = "IHE"
    Do ##class(%Prompt).GetArray("Deployment Type?",.dtype,.options,,,,$$$InitialDisplayMask+$$$MatchArrayMask)
    Write !, "Starting ", dtype," deployment..."
    Quit