So, there's 2 ways to read this, either we want an "exists" check, or following the SQL, we want a count of all instances.   This snippet can be set to do either case based on the existscheck boolean.  Ideally though, you would have an index defined, and this could be read much more efficiently than having to scan an entire global

set count=0
set existscheck=0 //Set to 1 if we only want to find first instance
set targetValue=1329
set key = ""
for   {
    set key = $ORDER(^DataTest(key))
    if targetvalue = +$LG(^DataTest(key),2) do $INCREMENT(count)
w !,"Count value is "_count

You absolutely can do this.   Each namespace is set with a Globals DB and a Routines DB.   The Globals are your default data storage, and the Routines are where your code lives

Further to this, there are an array of mapping features allowing your data and code to be spread over multiple databases.   You can read more about this here:

Having just done the same thing today, following Marc's comment (which is the same code in the documentation for MIMEParts) should get you what you need.

As it stands, I'm pretty sure you are just passing a handle to a stream to the FormData, rather than referencing the content of the stream.  This section of the example will correctly populate the HTTP Request body:

  // Write out Root MIME Element (containing sub-MIME parts) to HTTP Request Body.
    Set writer = ##class(%Net.MIMEWriter).%New()
    Set sc = writer.OutputToStream(tHttpRequest.EntityBody)
    if $$$ISERR(sc) {do $SYSTEM.Status.DisplayError(sc) Quit}
    Set sc = writer.WriteMIMEBody(rootMIME)
    if $$$ISERR(sc) {do $SYSTEM.Status.DisplayError(sc) Quit}

There can be more to "speed" that just execution time of your code.  If you need to add an index to help performance, then a Caché SQL query will be able to utilise it without any code changes.  If you are using $Order, then you need to spend some time writing and testing your new code.

I typically use SQL to identify objects, then Object methods to interact with them, but for simple updates of large numbers of objects, I'll usually use a simple SQL Update.  The beauty of Caché is the flexibility to use the best tool for the task at hand

Hi Javier

I did this by implementing a fromJSON method on each class, which allows me to do what you describe.  By moving this to the persistent class, I don't have to worry about instantiating or accessing the object, but can just apply a JSON update to an object

The details are in

Hope this helps

Just to add a word of warning.  The syntax for %Object is only available in 2016.1, and is deprecated in favour of similar but incompatible objects and syntax in later versions.  If you have the choice of versions, it would be wisest to adopt 2016.2+ and use the DynamicObject class and methods, as this will be more futureproofed

Details are at