In short i've got this array [73,4,75,2,56,2,58,1,57,1,45,1] and some how i want to manipulate this data into a UI dashboard just to monitor how many times an object appears. In this case 73 is the id in my back end application for a lemon and it appears 4 times and so on. To recap this sequence [0 2 4 6 8 10] contains the id's of my objects and odd sequence in the middle is the count times of the object.
Where do i start for example if my array gives eg [73,45] so to draw in my ui i got 45 lemons?
The screenshot of the debug window, for where the payload is
Your question is not very clear to me. What do you mean by “start” ?
As this is "your backend application" - i strongly suggest you transmit JSON instead if arrays.
JSON (like XML) is extensible and transforms with very little effort into a JS object.
The problem with arrays (like CSV) is that any change in format ruins the whole party where as
{
"lemons": 4
}
will ALWAYS be 4 lemons and accessible as a JS object property payload.lemons
even if in the future you change that to
{
"lemons": 4,
"unit_price": 40,
"stock_no": "L12345",
"description": "Fresh Lemons"
}
For example i might get a value decoded out of my node, as byte array. Here as [73,45] it means the first number will represent an object id (in this case lemons) and after the comma the population(count) of them. It can be more populated as described above.
@Steve-Mcl
Steve i cant transmit a JSON as my medium is Lora, already sorted, compressed and encoded for getting the payload as minimised as it is. Hence the form of this information.
[73,4,75,2,56,2,58,1,57,1,45,1]
Is the trade off really worth it? Have you measured and evaluated that transmitting JSON vs a dumb array is the bottleneck? (this might be worth a read)
Anyhow ...
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1 Like
@Steve-Mcl - Afraid so - LORA is really strict on packet sizes so no-one is going to send raw JSON. (You can but it's a total waste when you may have only 20-40 bytes.)
oh well - the solution offered will work so long as the array always has an even number of elements and the spec doesnt change!
1 Like
I understand that the input is a buffer of hexadecimal values where the first identifies the type (e.g. "Lemon") and the following hexadecimal specified the quantity.
... but I don't understand what you exactly want from us. Where do you need our help ? What do you want to do with that buffer array ?
Steve yes, that database creation of id's inside the function worked, though i cant display the last object. In this case the grapefruit 45,1 or whatever i add to the end of the array and tweak the id's inside the function for injecting it. Thanks a lot Steve
@janvda I want to create a gauge or similar dashboard in order to visualize somehow the generated data. I have a generated JSON file on the other end with those names, but i couldn't relay whole names so i id'ed them to reduce the payload.
change the for loop to length - 1 (instead of length - 2)
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