OK, it took me quite a bit to get my head wrapped around, but I've come up
with a solution that works for me. In order to dive into the nested array
and access the indexes in there, I had to resort to a macro renderIndex(),
but, as a positive side effect, this makes the code more readable. So
here's the example code. Feel free to comment if I unnecessarily
complicated it. Also, I still need to come up with a solution to add up
fields with numeric content in a JSON array. Input here would be greatly
appreciated
<!-- demo code -->
\define renderIndex(path: "0" index: "") <!-- renders indexes in JSON array
-->
<$set name="myFld2" tiddler="$(currentTiddler)$" index="$path$/$index$" >
Displaying $path$/$index$: <<myFld2>><br>
</$set>
\end
<$list filter="[tag[Facility]]">
<$view field="title"/><br>
Actions array Length:<br>
<$set name="arrLength" filter="[<currentTiddler>indexes[/Actions]count[]]">
Array Length: <<arrLength>>
</$set>
Actions array Full Content as JSON string:<br>
<$set name="myVar" tiddler=<<currentTiddler>> index="/Actions">
<<myVar>>
</$set>
Looping through Actions array:<br/>
<$list variable="arrayIndex" filter="[<currentTiddler>indexes[/Actions]]">
<$set name="myFld",
filter="[<currentTiddler>indexes[/Actions]addprefix[/Actions/]]"
select=<<arrayIndex>> >
Displaying contents of <<myFld>> as JSON string:<br>
<$transclude tiddler=<<currentTiddler>> index=<<myFld>> /><br>
<!-- Accessing fields in nested array -->
<$macrocall $name="renderIndex" path=<<myFld>> index="Action Date" />
<$macrocall $name="renderIndex" path=<<myFld>> index="Action Type" />
</$set>
</$list>
</$list>
<!-- demo code ends here -->
So, Joshua and Tony, thanks so much for helping me on the way. Was quite a
bit of a learning curve, but I enjoyed it.
Best, Werner
Am Montag, 13. Juli 2020 01:34:00 UTC+2 schrieb Joshua Fontany:
>
> I think you are almost there. One thing to keep in mind in Tiddlkywiki is
> the difference between "shorthand" Wikitext and "long form" Widgets.
>
> {{Title##Index}} is "shorthand" Wikitest that is then rendered into the
> following by the TW core:
> ```
> <$tiddler tiddler="Title">
> <$transclude tiddler=<<CurrentTiddler>> index="Index" />
> </$tiddler>
> ```
> As you can see, leaving out the first part, like so {{##Index}} would
> retain the value of the "current" <<currentTiddler>> variable and just use
> the <$transclude> widget to pull an Index. Similarly, if you leave out the
> "variable" parameter of a $list widget, it assumes you want to set the
> <<currentTiddler>> variable in each rendered tempalte. This is equivalent
> to your "each()" request. (Make sure to have an empty line after the
> opening <$list> tag if you want block fomatting.)
>
> The next thing to note is that with JsonMangler you always want to use
> full paths to any nested data. Always consider the Tiddler as the object,
> and path from the root to the required data. Your list would look like so:
> ```
> <$list filter="[tag[Facility]]">
>
> <$set name="arrLength" filter="[<currentTiddler>indexes[/Actions]count[]]">
> Facility Array Length: <<arrLength>>
> <$list variable="arrItemPath"
> filter="[<currentTiddler>indexes[/Actions]addprefix[/Actions]]" >
>
> <<arrItemPath>>: <$transclude tiddler=<<currentTidler>>
> index=<<arrItemPAth>> />
> </$set>
> </$list>
> ```
>
> Best,
> Joshua Fontany
> On Sunday, July 12, 2020 at 7:11:12 AM UTC-7 Werner wrote:
>
>> Hi Joshua,
>>
>> thanks so much for your answer. This has taken me a lot further.
>>
>> But, reconsidering my original question, I found, that, maybe, I got
>> stuck too much in the procedural paradigm, and a more elegant approach
>> would be, if one could could use each[] for looping through a JSON array.
>> Taking your example this should look something like:
>>
>> <$list filter="[[MyJson]indexes[/path/to/array]each[]]">
>> {{##FieldFromJsonArray}}
>> </$list>
>>
>> I tried to do it, but didn't succeed. I understand that each[] expects a
>> list separated with spaces, so my assumption would be that this does not
>> work unless an overloaded version of each[] is provided. OTOH, I found an
>> undocumented function ForEach[] in JSONMANGLER. Any clue?
>>
>> I created three JSON test tiddlers. One with a nested array of 4 elements
>> and another with 3 and a third one with a one-element array. I looped
>> through them like this
>>
>> <$list filter="[tag[Facility]]">
>> ...
>> <$set name="arrLength" filter="[indexes[/Actions]count[]]">
>> Array Length: <<arrLength>>
>> </$set>
>> </$list>
>>
>> and was able to display all fields and the array fields as JSON text.
>> Strangely, the arrLength variable displayed a value of 4 for all three
>> tiddlers. No idea why. Will have to dive deeper into it.
>>
>> Thanks again
>> Werner
>>
>>
>>
>> Am Samstag, 11. Juli 2020 21:24:07 UTC+2 schrieb Joshua Fontany:
>>>
>>> Hi,
>>>
>>> Great to see people experimenting with my tools.
>>>
>>> Two things to note. 1) 0-index based arrays can always have a new object
>>> written to an index equal to the length of the array. Example, "[0,1,2]", I
>>> can push "3" to {{MyJson##3}}, and it will be "[0,1,2,3]". Neat trick. 2)
>>> You can count an array's length using filters as long as you know the
>>> position of the array within the nexted JSON structure, like so:
>>> ```
>>> <$var name="arrLength" filter="[[MyJson]indexes[/path/to/array]count[]]">
>>> Array Length: <<arrLength>>
>>> </$var>
>>> ```
>>>
>>> Combine the two techniques like so (note the final slash on the new path
>>> gets added on as a prefix before adding the path to the array):
>>> ```
>>> <$var name="arrLength" filter="[[MyJson]indexes[/path/to/array]count[]]">
>>> <$var name="newIndex"
>>> filter="[<arrLength>addprefix[/]addprefix[/path/to/array]]">
>>> <$button setTitle="MyJson" setIndex=<<newIndex>> setTo="New Data" />
>>> </$var>
>>> </$var>
>>> ```
>>> You could use the form `setTo={{New Data Tiddler}}` to grab the new data
>>> from the text-field of the "New Data Tiddler", etc, etc.
>>>
>>> Best,
>>> Joshua Fontany
>>> On Friday, July 10, 2020 at 1:14:52 AM UTC-7 Werner wrote:
>>>
>>>> Hi Tony,
>>>>
>>>> thanks for taking your time and your extensive reply. Perhaps I've made
>>>> it too complicated. Ok, I try to reformulate it. Disclaimer also: I work
>>>> in
>>>> a corporate environment, so I'm not completely free in the tools I am
>>>> allowed to use (to my surprise, Node.js is ok - yessss!) and how much
>>>> information I can disclose.
>>>>
>>>> Let's put it that way: I have set up an internal information repository
>>>> which contains more or less textual information only so far. But now and
>>>> then, I would like to display some figures. And I would have to perform
>>>> some simple arithmetics with that figures (basically summing up).
>>>>
>>>> Let's call the things I am looking at "facilities". A "facility" should
>>>> be displayed in a templated tiddler, displaying textual and quantitative
>>>> information. Each "facility" can feature several "units" (that's the 1:n
>>>> relation), figures for which should also be displayed and/or shown as a
>>>> grand total.
>>>>
>>>> The data for the facility/unit information should initially come from
>>>> an Excel table. For further use (the CRUD part), I would like to create a
>>>> TW-based interface. As "facility" is a comprehensive entity for my
>>>> purposes, I thought it would be ok to store it in a nested JSON tiddler,
>>>> i.e. store the units per facility in a JSON array. This, of course, breaks
>>>> the RDBMS dogma, but it saves me from having to fiddle with primary keys.
>>>> Mimicking a RDBMS in TW is definitely not a rabbit hole I want to jump
>>>> into. If I needed something like that, I would try if I could connect a DB
>>>> backend via Node.js (in my special environment I would end up with SQLite
>>>> or ODBC), and let this do the grunt work.
>>>>
>>>> All this being said, here's the core of my question: Accessing nested
>>>> JSON data using Joshua Fontenay's JSONMANGLER plugin works great, as long
>>>> as the index position is known, but I need a way to determine the length
>>>> of
>>>> a variable-length array in a JSON structure, for not running out-of-bounds
>>>> while looping into the nested data. I understand $:/History is such a
>>>> variable-length array, and thanks for pointing me at this. In that case,
>>>> maybe I need to look up how data are retrieved from there. I know, as a
>>>> workaround, I still could store the number of units as a data field in the
>>>> JSON structure, but then I would have to take care of it programatically,
>>>> which I want to avoid.
>>>>
>>>> Thanks again and apologies for any confusion I caused
>>>> Werner
>>>>
>>>>
>>>> TW Tones schrieb am Freitag, 10. Juli 2020 um 01:19:01 UTC+2:
>>>>
>>>>> Werner,
>>>>>
>>>>> Despite clearly having a lot in common with an understanding of
>>>>> databases I don't completely follow you need or argument here. However I
>>>>> believe I can offer you some helpful leads.
>>>>>
>>>>> One part that confuses me is your 1:n or one to many, I have already
>>>>> build one to one, one to many and many to many half a dozen ways without
>>>>> a
>>>>> data tiddler in tiddlywiki. What is the particular issue here?
>>>>>
>>>>> First look at tiddlywikis existing functionality.
>>>>>
>>>>> - The history mechanism stores tiddler titles and more during a
>>>>> session in the $:/historyList this may be an analogue
>>>>> - The Import and export mechanism extract and package tiddlers as
>>>>> json representations
>>>>> - Mohammad's Trash Plugin moves deleted tiddlers into another
>>>>> structure to keep them aside, I think it is JSON as well.
>>>>> - In my demo site here
>>>>> <https://anthonymuscio.github.io/ActiveTiddler.html> the active
>>>>> tiddler process extracts titles from the history list using
>>>>> splitregexp not
>>>>> standard JSON as the key is not unique
>>>>>
>>>>> However It would not necessarily be too concerned about using tiddlers
>>>>> unless your number will be truly astounding in numbers. We had a 66,000
>>>>> word tiddler example in the last year and that was single file.
>>>>>
>>>>> Speculation
>>>>>
>>>>> If you packed more static tiddlers (eg a reference table) into a
>>>>> plugin and access them as shadow tiddlers you are effectively packing
>>>>> them
>>>>> into a json file and allow yourself to edit exceptions and the database
>>>>> becomes the combination of the packaged and overwritten providing a lot
>>>>> of
>>>>> flexibility to your design. In effect you CRUD will make use of standard
>>>>> tiddlywiki features, just treat the records like standard tiddlers. The D
>>>>> or delete of CRUD could get smart (adding and removing from JSON) or you
>>>>> could simply flag deleted tiddlers as such and treat them as deleted with
>>>>> an occasional rebuild recommended after N tiddlers are flagged as deleted.
>>>>>
>>>>> I can already foresee a lot of sophisticated features being possible
>>>>> including tracing and logs, difference engines, database snapshot at a
>>>>> point in time and more. I have recently designed an alternative to shadow
>>>>> tiddlers I call ghost tiddlers that may also be a useful algorithm.
>>>>>
>>>>> Offer
>>>>> I as a tiddlywiki superuser, I am investing totally in the TiddlyWiki
>>>>> platform, if you are interested in collaboration to build a database
>>>>> model
>>>>> process, making full use tiddlywiki's unique features I think it will be
>>>>> a
>>>>> good investment in the future.
>>>>>
>>>>> Lets start the conversation.
>>>>>
>>>>> Regards
>>>>> Tony
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Friday, July 10, 2020 at 5:38:31 AM UTC+10, Werner wrote:
>>>>>>
>>>>>> Dear all, heavy user and rare poster here. Using TW has become a
>>>>>> daily treat for me, but I have managed to still stay at the surface so
>>>>>> far.
>>>>>> Now, I have to dive in deeper.
>>>>>>
>>>>>> I have been using TW so far to store semi-structured information, but
>>>>>> now I need to integrate structured information, i.e. a database
>>>>>> featuring
>>>>>> an 1:n relation.
>>>>>>
>>>>>> I thought it might be a good idea using JSON. I also thought, for my
>>>>>> purposes, I don't want to mimic an RDBMS in TW with all the primary key
>>>>>> hassles and a deluge of .TID files (I am running TW on Node.js), so I
>>>>>> wanted to use a JSON tiddler for the entities and use arrays in JSON for
>>>>>> sub-entities.
>>>>>>
>>>>>> I came across Joshua Fontenay's JSONMangler plugin (Kudos, Josh!) and
>>>>>> so far so good.
>>>>>>
>>>>>> BUT
>>>>>>
>>>>>> Eventually I want to implement CRUD (create-retrieve-update-delete)
>>>>>> functionalities for this special data. And I want to display the 1:n
>>>>>> relation in a single tiddler. And this is where I'm stuck at the moment:
>>>>>>
>>>>>> - how to get the total number of array items in a JSON array in order
>>>>>> to be able to display the 1:n
>>>>>>
>>>>>> apart from the variable array length, the JSON structure is fix, so
>>>>>> everything else should be fairly straightforward. OK, there are some
>>>>>> numeric fields in the array I need to sum up, but one thing after the
>>>>>> other...
>>>>>>
>>>>>> Any insight would be greatly appreciated
>>>>>>
>>>>>> Best,
>>>>>> Werner
>>>>>>
>>>>>>
>>>>>>
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