Sending and receiving words and numbers between the Arduino and database works perfectly. But if I want to retrieve longer arrays from the database (e.g. the array with the LEDs that should light up and their color in hex code for the drawing mode) the Arduino blocks. At first I thought it was due to the fact that not enough local flash memory was available on the board. But that was not the problem. Then I thought that by default it would only retrieve a max number of items from an array (like a default max limit with Strapi for example) I tweaked the queries a bit but again the problem was not there. Time for a coaching session

Simon said I could use a long string instead of an array (with array.join()). I tried this, it was already going better, I could retrieve more data, but still only data for 50 LEDs (instead of 25 with the array), and there are 300 of them. It seemed that the string was only allowed to be around 400 characters. If I wanted to send a drawing for the whole strip, my message (joined array) would be around 2500 character long. I dived into the WiFi library and saw indeed that a maximum response size was defined, this was 400. I wanted to change this to 2000, but the Arduino did not like this and restarted at random moments. My string could then be about 2000 characters long. But it is not a solution if the Arduino constantly fails. The string I use to address my lights looks like this.

The hardest part then was parsing this string in C++. Arrays do more difficult here than in JavaScript. Also a stumbling block: every time I wanted to modify and test my C++ code I had to upload it to the board, this took a minute each time. At next consultation Simon said I should split the arrays, it was not an option that you could only draw on max 50 lights out of 300, I agreed. I split the array as follows: 1 array for the lights to be lit [234, 201, 24, ...], and 1 array for each the rgb values. r= [122, 123,...], g= [98, 91,...], b= [98, 91,...]. But again, the Arduino board had performance isues with it. Live drawing was no longer as life because it had to retrieve 4 arrays each time. So also this was not an option

Let's just start over. I created an array that has a default length of 300 with only 0's and 1's. This should work since the maximum length of a string is 400. 0 means that the led on that index is not lit, 1 means it is. Very basic. For now I skip the color of the led. Here C++ had a problem with the 0's and 1's when I changed this to H and L everything worked fine. I could draw in the tree (the full 300 led's, but no color yet)

Then I thought of just choosing 1 fixed color with which you make the whole drawing, so not multiple colors per drawing. But that's not nice, I wanted that each led could theoretically have a different color and that you could draw in the tree with different colors. This color you can choose with a html color input. But color codes in the hex form take too many bytes. Why can't I work with different predefined colors. The standard rainbow colors. Then I don't have to work with H and L, but I can grab the first letter of a color each time and handle this in C++ in an else statement. The array would look like this:

For this drawing:

How it's handeld in C++:

In Javascript, these larger arrays would work, and I would not have thought about making the code more effienct and smaller. You don't see the consquencies of it right away because our computers are so fast, but in C++ with an Arduino you do. This problem has taught me to write code as effienctly as possible and to use small data sizes for the database.