Fetch Message Header Data

(Originally posted to InterSystems CODE by @Dmitry Maslennikov) The following code snippet outputs message header data in Ensemble. The class method "fetchExecute" runs the process, and the result is stored in the argument "qHandle":

include Ensemble
Class DAiMor.fetchMessageHeaderData extends %RegisteredObject
{

Query Fetch(Namespace As %String) As %Query(ROWSPEC = "Namespace:%String,ID:%Integer,Type:Ens.DataType.MessageType,Priority:Ens.DataType.MessagePriority,Invocation:Ens.DataType.MessageInvocation,TimeCreated:Ens.DataType.UTC,TimeProcessed:Ens.DataType.UTC,Status:Ens.DataType.MessageStatus,IsError:%Boolean,ErrorStatus:%Status,CorrespondingMessageId:%Integer,SessionId:%Integer,SourceConfigName:%String,TargetConfigName:%String,SourceBusinessType:Ens.DataType.MessageBusinessType,TargetBusinessType:Ens.DataType.MessageBusinessType,BusinessProcessId:%Integer,TargetQueueName:%String,ReturnQueueName:%String,MessageBodyClassName:%String,MessageBodyId:%String,Description:%String,SuperSession:%String,Resent:%String") [ SqlProc ]
{
}
ClassMethod FetchExecute(ByRef qHandle As %Binary, Namespace As %String = "") As %Status
{
set namespaces=""
if Namespace'="" {
set list=$lfs(Namespace,",")
for i=1:1:$ll(list) {
set ns=$zcvt($lg(list,i),"U")
continue:'$d(^%SYS("Ensemble","InstalledNamespace",ns))
set qHandle("list",ns)=""
}
}
set queryDef=##class(%Dictionary.QueryDefinition).%OpenId(..%ClassName(1)_"||Fetch")
set rowspec=$lfs(queryDef.Parameters.GetAt("ROWSPEC"))
set qHandle("rowspec")=rowspec
Quit $$$OK
}
ClassMethod FetchClose(ByRef qHandle As %Binary) As %Status [ PlaceAfter = FetchExecute ]
{
Quit $$$OK
}
ClassMethod FetchFetch(ByRef qHandle As %Binary, ByRef Row As %List, ByRef AtEnd As %Integer = 0) As %Status [ PlaceAfter = FetchExecute ]
{
set ns=$get(qHandle("current"))
if ns="" do nextNamespace
set rowspec=qHandle("rowspec")
do queryRow
set qHandle("current")=ns
Quit $$$OK
queryRow
quit:ns=""
new $namespace
set $namespace=ns
if '$d(qHandle("query"),query) {
set st=##class(%SQL.Statement).%New()
do st.%Prepare("SELECT '"ns"' Namespace, * FROM Ens.MessageHeader")
set query=st.%Execute()
set qHandle("query")=query
}
if query.%Next() {
set Row=$lb()
for i=1:1:$ll(rowspec) {
set prop=$p($lg(rowspec,i),":")
set $li(Row,i)=query.%Get(prop)
}
} else {
do nextNamespace
do queryRow
}
quit
nextNamespace
kill qHandle("query")
if $d(qHandle("list")) {
set ns=$order(qHandle("list",ns))
} else {
set ns=$order(^%SYS("Ensemble","InstalledNamespace",ns))
}
if ns="" {
set AtEnd=1
}
Quit
}
}

Here's a link to the code on GitHub: https://github.com/intersystems-community/code-snippets/blob/master/src/cls/DAiMor/fetchMessageHeaderData.cls