Convert Struct to Readable JSON(Pretty Print)
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Every struct I pass to jsonecode gets converted to a 1 by N char array with no newline chacters. Therefore, when I export the json as to a text file I only have one line. The file is not easly readble because I have to scroll the JSON text horizontaly. How can I make jsonencode's output easily readable(pretty print)?
I get this.
{ "firstName": "John", "lastName": "Smith", "age": 25, "address": { "streetAddress": "3 Apple Hill Dr", "city": "Natick", "state": "MA", "postalCode": "01760" }, "phoneNumber": [ { "type": "home", "number": "123 456 7890" }, { "type": "cell", "number": "098 765 4321" } ] }
I want something like this.
{
"firstName": "John",
"lastName": "Smith",
"age": 25,
"address":
{
"streetAddress": "3 Apple Hill Dr",
"city": "Natick",
"state": "MA",
"postalCode": "01760"
},
"phoneNumber":
[
{
"type": "home",
"number": "123 456 7890"
},
{
"type": "cell",
"number": "098 765 4321"
}
]
}
5 Comments
Davide Serina
on 8 Dec 2022
Moved: DGM
on 8 Dec 2022
ciao, come si fa ad ottenere una struttura come quella che hai scritto partendo da una struttura su matlab?! cioè non riesco a fare gli annidamenti. bisogna usare un ciclo for???
Sean Bone
on 9 Dec 2022
Ciao @Davide Serina, la tua domanda si riferisce a come creare una struttura annidata in MATLAB o a come convertire una struttura annidata in JSON? Oppure ancora a come convertire una struttura MATLAB in JSON con le indentature per rappresentare gli annidamenti?
Accepted Answer
Sean Bone
on 30 Jan 2022
In more recent Matlab versions, you can do the following:
jsonencode(data, "PrettyPrint", true);
Note that this option was only introduced in Matlab R2021a, despite the documentation for jsonencode not mentioning this explicitly.
More Answers (2)
Robin Larsson Nordström
on 3 Oct 2023
Edited: Robin Larsson Nordström
on 3 Oct 2023
For the provided example the default pretty print output will be fine:
txt=jsonencode(data, "PrettyPrint", true);
However if the input data struct contains fields with vectors or matrices the jsonencode PrettyPrint in Matlab 2023b adds a newline for each element, making the encoded text hard to read even when the number of elements are not that many.
Post-processing the output with a few regexprep lines to remove white-spaces inside vectors and matrices have worked well for me. Example below with the struct from the Matlab help on jsonencode PrettyPrint example with the addition of an extra field Q storing a 4 X 4 matrix:
s=[];
s.Width = 800;
s.Height = 600;
s.Title = 'View from the 15th Floor';
s.Animated = false;
s.IDs = [116, 943, 234, 38793];
s.Q = round(randn(4),3);
txt=jsonencode(s,PrettyPrint=true)
% remove white-spaces inside vectors and matrices
txt = regexprep(txt,',\s+(?=\d)',','); % , white-spaces digit
txt = regexprep(txt,',\s+(?=-)',','); % , white-spaces minussign
txt = regexprep(txt,'[\s+(?=\d)','['); % [ white-spaces digit
txt = regexprep(txt,'[\s+(?=-)','['); % [ white-spaces minussign
txt = regexprep(txt,'(?<=\d)\s+]',']'); % digit white-spaces ]
txt
Gaurav Garg
on 20 Nov 2019
Hi,
1 Comment
Laurel Keyes
on 28 Jun 2021
This file is helpful but not if you have nested structures. I use a quick and dirty method, where you just string-replace the commas or brackets like so:
% assuming your structure is saved to val:
str = jsonencode(val);
% add a return character after all commas:
new_string = strrep(str, ',', ',\n');
% add a return character after curly brackets:
new_string = strrep(new_string, '{', '{\n')
% etc...
% Write the string to file
fid = fopen("filename.json",'w')
fprint(fid, new_string);
fclose(fid);
This method will not indent but does allow a slightly better formatting, no matter the structure of your json
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