> creates the specified path if it does not exist. Does it? No, jsonb_replace() doesn't create an element, if it doesn't exist. I think, otherwise it can be confusing, so probably jsonb_add() may be more appropriate (and, actually, this function was already mentioned in previous discussions).
On 18 May 2015 at 22:57, Ryan Pedela <rped...@datalanche.com> wrote: > On Mon, May 18, 2015 at 8:41 AM, Ryan Pedela <rped...@datalanche.com> > wrote: > >> On Sun, May 17, 2015 at 9:41 PM, Josh Berkus <j...@agliodbs.com> wrote: >> >> Is there a particular reason why "+" makes more sense as "shallow >>> concatination" and "||" makes more sense as "deep concatination"? Like, >>> something in JS or other client languages which would make that >>> preference make more sense to users? >>> >> >> As someone who uses JSON day-to-day in Javascript and Python, I >> personally don't think || or + matters much. Python uses json.loads() for >> JSON concat and you have use a 3rd-party library in Javascript if you want >> that functionality such as JQuery.extends(). I agree with Peter that we >> need deep concatenation, but I don't think there is any standard for the >> operator. I think the word "shallow" should be added to the docs though. >> >> What is far more important than shallow or deep concatenation for the >> document database use case is being able to delete or replace/update a >> specific, nested path in the JSON object. It looks like that is possible >> with the minus operator and jsonb_replace(). This is great, however it took >> me awhile to figure out the path syntax. I think adding a paragraph to the >> docs explaining the path syntax would help. >> > > Having looked at this more, I think I understand the problem Peter has > identified and it is a significant usability problem in my opinion. I think > the word "concatenate" has confused me because I think of it as a > higher-level operation when I want to merge two, large JSON objects which > isn't a very common operation, at least for me. What is absolutely required > for the document database use case is the following: > > 1. Get element at any arbitrary path. ( #> operator ) > 2. Delete any arbitrary path. ( minus operator ) > 3. Replace/update element at any arbitrary path. ( jsonb_replace ) > 4. Add element to any arbitrary path. ( ? ) > > It is #4 that does not seem to exist unless jsonb_replace() creates the > specified path if it does not exist. Does it? I am not currently at my desk > to test it myself. > > If not, deep concatenation would solve this problem, but I can also see > another solution. Use + for shallow concatenation since it really means > "add element to top-level path" as Peter suggests. Then add another > function: jsonb_add( target jsonb, path text[], new jsonb ) to add element > at any arbitrary path. Then leave || for deep concatenation in 9.6 or > whenever. > > If jsonb_replace() satisfies #4 then I think everything is fine. Without > #4 however, jsonb would remain an incomplete document database solution in > my opinion. > > Thanks, > Ryan Pedela > >
