How to parse Dynamic JSON file in Simulink?

Hi All,

I am currently working on a usecase where I have to parse dynamic json file in simulink model. I have tried using matlab function jsondecode in simulink function block but the function jsondecode is not supported for code generation. Is there any other way to parse json file in simulink?

Answer 1

[Riya]

Hello Arhan,

As per my understanding you want to know how to parse Dynamic JSON file in Simulink.

Please note that one approach is to use a third-party JSON parsing library that is compatible with Simulink code generation. Here is an example of how you can achieve this using the "JSONlab" library:

1. Download the “JSONlab” library from the MATLAB File Exchange: https://www.mathworks.com/matlabcentral/fileexchange/33381-jsonlab-a-toolbox-to-encodedecode-json-files

2. Extract the downloaded files and add the “JSONlab” folder to your MATLAB path.

3. In your Simulink model, use a MATLAB Function block to parse the JSON file. Here's an example of how you can do this:

function parsedData = parseJSONFile(jsonFile) 
       % Load the JSONlab library 
       addpath('path/to/jsonlab'); 
 
       % Read the JSON file 
       jsonStr = fileread(jsonFile); 
 
       % Parse the JSON string 
       parsedData = loadjson(jsonStr); 
 
       % Remove the JSONlab library from the MATLAB path 
       rmpath('path/to/jsonlab'); 

4. Connect the input of the MATLAB Function block to the JSON file path input and the output to the parsed data output.

5. Generate code from your Simulink model. The MATLAB Function block will use the “JSONlab” library for parsing the JSON file during code generation.

Make sure to replace `'path/to/jsonlab'` in the code above with the actual path to the “JSONlab” library on your system.

By using this approach, you can parse dynamic JSON files in Simulink even though the `jsondecode` function is not supported for code generation.

I hope it helps.

[Toby]

This solution doesn't appear to work as the functions used to add jsonlab are not supported for code generation. The following error message appears:

Function 'addpath' not supported for code generation.