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Entry  16 Feb 2018, Amy Roberts, Suggestion, respect capitalization option in db_get_values mjsonrpc method? 
    Reply  17 Feb 2018, Amy Roberts, Suggestion, respect capitalization option in db_get_values mjsonrpc method? 
       Reply  08 Mar 2018, Thomas Lindner, Suggestion, respect capitalization option in db_get_values mjsonrpc method? 
Message ID: 1348     Entry time: 08 Mar 2018     In reply to: 1340
Author: Thomas Lindner 
Topic: Suggestion 
Subject: respect capitalization option in db_get_values mjsonrpc method? 
Hi Amy,

Let me start by explaining the reasoning for the default behavior of db_get_values.  I think it was mentioned elsewhere, but is worth repeating.

The ODB is case-insensitive.  So the ODB key name /Equipment/dcrc01 is equivalent to /equipment/Dcrc01; you could rename the variable like that and your 
frontend programs would still work fine.  Javascript, of course, is case sensitive.  However, we want our default MIDAS webpages to work no matter what the 
capitalization is for a particular ODB; so, for instance, the main status.html page should work whether the ODB key is called /Runinfo or /rUnInFo, since both 
of these are equivalent from the point of the ODB (and the rest of MIDAS).

The solution was to have the db_get_values method convert all key names to lower case and consistently use the lower case spelling when writing the main 
MIDAS webpages; this makes us insensitive to ODB capitalization (and hence makes the MIDAS pages behaviour match the previous mhttpd behaviour).

That being said, I agree that it is sometimes counter-intuitive to use lower case key names with db_get_values, particularly if you are directly creating ODB 
keys and writing the javascript at the same time.  So we have added the option 'preserve_case' to db_get_values, which preserves the ODB key name 
capitalization (the default behaviour is still to make key names lower case).

This option should not be used for writing any standard MIDAS webpages (ie, webpages that will be used across multiple experiments), since standard MIDAS 
webpages should not break when ODB key name capitalization changes.  For the same reason you should use caution with this option for custom pages as 

With regards to your second question: the db_save method is not deprecated and you could use that method instead.  The use-case for the db_save method 
is different; db_save is used to make dumps of the ODB.  In that case it seems best that key name capitalization is preserved.  Otherwise if you dumped your 
whole ODB and then reloaded it from the dump the new ODB would be different (in key capitalization) from the old ODB; different in a way that shouldn't 
matter but still probably not the behaviour that people expect.

Admittedly this means that the mjsonrpc API is not always intuitive; but I think is the best we can do, given the underlying case-insensitivity of the ODB.


> It appears I needed to read the documentation more closely - the method db_save
> does respect key-name capitalization and solves my problem.
> Is db_save considered a deprecated method?  If so, I'd reiterate my suggestion for
> a capitalize-preserve option for db_get_values.
> Otherwise, I'll plan on using db_save.
> > I'd like to use the mjsonrpc db_get_values method, but (as indicated in the
> > documentation) it returns all ODB keys as lowercase.
> > 
> > This breaks quite a lot of my code - it was written with the old AJAX commands,
> > and these did respect the capitalization of the ODB keys.
> > 
> > Would it be possible to add a capitalization-preserve option to db_get_values? 
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