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· Mar 30, 2020

StreamLocation doesnt seem to affect where streams are stored

#Object Data Model #Caché

Hi-

I have a class that specifies that streams should be stored in SSA.DocumentCacheS, however, they are getting stored in CacheStream instead.

How can I get streams to properly store in SSA.DocumentCacheS?

Here's the section from my storage definition that shows the StreamLocation

<DataLocation>^SSA.DocumentCacheD</DataLocation>
<DefaultData>DocumentCacheDefaultData</DefaultData>
<IdLocation>^SSA.DocumentCacheD</IdLocation>
<IndexLocation>^SSA.DocumentCacheI</IndexLocation>
<StreamLocation>^SSA.DocumentCacheS</StreamLocation>
<Type>%Storage.Persistent</Type>

But when I look at the globals created:

Global ^SSA.DocumentCacheD
^SSA.DocumentCacheD("997ey01BWB")=$lb("",$lb($lb($c(0,19,1,14,1)_"^CacheStream"_$c(3,4,2,2,1),,"^CacheStream")),$lb("Bronchitis.tiff"),$lb("8416350"))                                                                                                                   
Global ^SSA.DocumentCacheS  [Global does not exist]
Global ^

Any thoughts on where I went wrong?

Thanks

Discussion (6)2
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Tomas Vaverka · Mar 30, 2020

Please, what is definition of your  stream property and how do you create its data?

If the stream is type of %Library.GlobalCharacterStream or %Library.GlobalBinaryStream, the location of the streams depends if you write data directly to the stream property or if you created the stream first and assign it to stream property:

Class tv.test Extends %Persistent,
{
Property MyStream As %GlobalCharacterStream;
}

USER>s x=##class(tv.test).%New()
 
USER>w x.MyStream.%Location
^tv.testS
USER>w x.MyStream.Write("My Data")
1
USER>w x.%Save()
1
USER>zw x.MyStream.GetStreamId()
$lb($c(0,16,1,11,1)_"^tv.testS"_$c(3,4,4,2,1),"%GlobalCharacterStream"

BUT:

USER>s x=##class(tv.test).%New()
 
USER>s str=##class(%GlobalCharacterStream).%New()
 
USER>w str.%Location
^CacheStream
USER>s x.MyStream=str
 
USER>w x.MyStream.%Location
^CacheStream
USER>w x.MyStream.Write("My Data")
1
USER>w x.%Save()
1
USER>zw x.MyStream.GetStreamId()
$lb($c(0,19,1,14,1)_"^CacheStream"_$c(3,4,2,2,1),"%GlobalCharacterStream")

Therefore if you do not want to change the location of the stream, is better to use CopyFrom method insterad:

USER>s x=##class(tv.test).%New()
 
USER>s str=##class(%GlobalCharacterStream).%New()
 
USER>w str.Write("My Data")
1
USER>w x.MyStream.CopyFrom(str)
1
USER>w x.%Save()
1
USER>zw x.MyStream.GetStreamId()
$lb($c(0,16,1,11,1)_"^tv.testS"_$c(3,4,5,2,1),"%GlobalCharacterStream")

Please, let us know if it corresponds to your findings.

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Robert Cemper · Mar 30, 2020

Hi Jenna,

I took some time to verify my suspicion.  (Caché 18.1)

You depend on the type of stream that is used in your object

#A)  %Library.GlobalBinaryStream or %Library.GlobalCharacterStream

  • if you have no stream yet you run do obj.MyStream.Write("whatever") then your stream will land in ^SSA.DocumentCacheS as expected
  • but if you get an already existing external stream and set obj.MyStream = myStreamOref then just the oref / OID of the stream is set including ^CacheStream.

Which seems to be your case   sadcrying​​​​​​​  angry
it's not a big surprise as ENSEMBLE may still use the old style. 

#B) using %Stream.GlobalBinary, ...

  • Both cases ended as expected with the stream in ^SSA.DocumentCacheS It seems to me that a CopyFromStream happens during the assignment. I'd name it expected behavior.   smiley
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Jenna Poindexter · Mar 31, 2020

My stream definition is

Property Streams As list Of %CSP.CharacterStream;
 

I used the %CSP.CharacterStream because that is what was being created in the %request object and I figured it would be simpler to just add that stream to my collection.  

I understand why this would be stored in CacheStream as it it created by the CSP engine.   I think my solution is to use a %Stream.Character and actually copy the contents from the %CSP.CharacterStream rather than storing itself.

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