Re: How to write a soft record with a constant long string value

["Johnson, Andrew N. via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Tom,

On Aug 18, 2020, at 4:04 AM, Cobb, Tom (DLSLtd,RAL,LSCI) via Tech-talk <tech-talk at aps.anl.gov> wrote:

I would like to write a database file with a single record that holds a constant chunk of JSON (generated by a script at IOC build time). I would prefer to do this by writing the JSON into the database file itself, rather than having to use a separate file, or dbpf.

Does anyone know if this is possible?

You can load arbitrary JSON into a record info tag, but not directly into any other field type at the moment. It should be relatively easy to write device support or an aSub subroutine to copy the contents of an info tag into a long string field though:

woz$ cat ~/db/test.db 

record(lsi, "json") {

  info(json, {"this": ["is", "json"], # Comments,

    # spaces and newlines are stripped.

    "does": ["this", "help?"]})

}

woz$ bin/darwin-x86/softIoc -d ~/db/test.db 

dbLoadDatabase("/Users/anj/Software/epics/base-7.0/bin/darwin-x86/../../dbd/softIoc.dbd")

softIoc_registerRecordDeviceDriver(pdbbase)

dbLoadRecords("/Users/anj/db/test.db")

iocInit()

Starting iocInit

############################################################################

## EPICS R7.0.4.1-rc1-DEV

## Rev. R7.0.4.1-rc1-14-ga808e3c7900b79f22eb5-dirty

############################################################################

iocRun: All initialization complete

epics> dbli

json info(json, "{"this":["is","json"],"does":["this","help?"]}")

HTH,

- Andrew

-- 

Complexity comes for free, simplicity you have to work for.