Why is my web app unable to locate a file included during compilation?

I have a MATLAB app that depends on a data file, "test_data.xlsx". When the app is run from App Designer, this file is successfully found at runtime and the app runs without issue. However, when I compile this as a web app (with the data file included during compilation) and run it on MATLAB Web App Server, I get an error that the file can't be found. 

Why is my code not able to locate this file dependency, even when the file is included in the packaged CTF?

Answer 1

[MathWorks Support Team]

This may be due to the path used to access the file in your code. 

In deployed environments, the simplest way to obtain the full path to a file is using the which function:

if isdeployed
    file_path = which('test_data.xlsx');
end

Alternatively, you can construct the full file path using ctfroot:

if isdeployed
    file_path = fullfile(ctfroot,'folderA','test_data.xlsx');
end

For more information on both these options, see Include and Access Files in Packaged Applications.