Miyako, On Thu, Feb 1, 2018 at 12:33 PM, Keisuke Miyako via 4D_Tech <4d [email protected]> wrote:
> I don't think that actually proves that JSON Parse is throwing the > runtime error. > Agreed. But that is where it shows up so it's the place to start. rather than looking at the "line of code referenced in the error dialog" > perhaps you could activate debug log recording in verbose mode (2) > at the start of the offending method (and disable it a the end) > > http://doc.4d.com/4Dv16R5/4D/16-R5/SET-DATABASE-PARAMETER. > 301-3481818.en.html > > source code is stripped in a 4DC, so I wouldn't completely trust the line > of code printing in the error dialog. > Again, I agree and would do this is to track down an error. But my fundamental question is how do I validate a string as something that can be parsed before feeding it to JSON Parse where I'll get a runtime error? That's really all I'm looking for. The solutions I'm finding so far only work interpreted. > > how do you looks at the string to see if it begins with "{" or "[" ? > I use a case statement like: Case of :(length($str)<2) ` a valid string could be 2 chars: {} or [] :($str[[1]]="{") json parse :($str[[1]]="[") json parse array... End case Perhaps a better threshold definition would help. The smallest valid object is, I think: {"a":1} or seven chars. The smallest valid array would be [1] or three chars. So Case of :(length($str)<2) ` a valid string could be 2 chars: {} or [] :($str[[1]]="{")&;(Length($str)<7)` not possible :($str[[1]]="{") json parse :($str[[1]]="[") json parse array... End case > besides, you shouldn't have to look at the string in the first place if > you use JSON Parse with error handling. > I don't understand. How can I not look at the strings to see if they are valid if I'm getting an error attempting to parse them? 4D's parser is strict - it gags on strings with an extra comma for example: {"a":1, "b":2,} but not {"a":1, "b":2} I don't have a problem with it being strict I'm just trying to understand how to protect against runtime errors in this instance. Clearly it's in the data. But without a way to log the error it's hard to know where to start looking. Especially when it's the server that gets blocked by one. Perhaps I'm not handling this sort of problem the way most folks do. If so it's out of ignorance and not intransigence. I'm happy to be guided otherwise. -- Kirk Brooks San Francisco, CA ======================= We go vote - they go home ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:[email protected] **********************************************************************
