ispathvalid & mustBeValidPath: Validate path syntax, type, and extension

The typical use case is to check paths at the start of a script/function before saving/exporting, with human readable feedback if validation fails.

Syntax

tf = isvalidpath( inputPath ) checks if the platform can parse the path inputPath. Unlike isfolder and isfile, it does not verify that the path exists in the file system.

tf = isvalidpath( inputPath, pathType ) also checks that the location of inputPath is either a file or directory.

tf = isvalidpath( inputPath, "file", validExtensions ) also checks that inputPath contains a file extension from a provided set, validExtensions.

[ tf, Log ] = isvalidpath( __ ) additionally returns formatted log messages. Log.warning explains why a path is not valid. Log.info provides formatting tips. Use the disp function to print the log to the command window.

mustBeValidPath( inputPath, pathType, validExtensions ) function identically to isvalidpath but throws an error if the path format is not valid. pathType and validExtensions are optional.

Inputs

Argument	Description
inputPath	Path to validate. Supported path formats: Traditional path, to a file or directory, relative or absolute, e.g., C:\ffmpeg and ../file.dat. Unsupported path formats: Remote locations, e.g., s3://bucketname/. UNC paths, e.g., \\127.0.0.1\temp. DOS device paths, e.g., \\.\UNC\Server\Share\. URIs, e.g., file://C:/file.dat and http://example.com. All others not listed here. Text scalar, i.e., character vector or string scalar.
pathType	Valid location type of inputPath. Either: "any" - (default) Any path type is acceptable. "file" - Only a file path is acceptable, i.e., it must have a file name and a valid extension according to validExtensions. "dir" - Only a directory path is acceptable, i.e., it cannot have a file name or extension. "directory" - Same as "dir". Text scalar, i.e., character vector or string scalar.
validExtensions	Specifies which file extensions are valid if the input is a file path. Each entry must be either: (default) A period (.), representing any extension. Text beginning with a period character, e.g., ".mat". Empty text, {''} or "", representing no extension. "image", representing all raster image extensions MATLAB knows. Run the command [ imformats().ext ] to see the list. Character vector, cell array of character vectors, or string array.

Outputs

Argument	Description
tf	Whether the path valid or not according to the above options. Logical scalar.
Log	Formatted log messages. Struct scalar with the fields: warning - String. Explains why the path is not valid, or states when the location is ambiguous, e.g., "C:\example" could be either a directory or a file without an extension. Possible warning messages: Invalid path as per platform rules, e.g., "dir\dir\dir\:". Directory path includes a file extension, e.g., "dir\file.ext". File path lacks a file name, e.g., "dir\". File path missing valid user-specified extension, e.g., "dir\file". Path could be a file OR a directory, e.g., "dir\ambiguous". The path may still be valid. info - String. Contains additional formatting information and explains formatting issues which will not affect the use of path in practice, as they are handled correctly by the platform. Possible info messages: Path altered by platform during parsing, e.g., any of the below. Redundant name elements removed by platform, e.g., ".\dir". Path has incorrect separators for platform, e.g., "dir\dir/dir". Path includes consecutive separators, e.g., "dir//dir/". If there are no messages, the fields of Log will be "", i.e., a zero length string. Use the disp function to print the messages to the command window, e.g., disp( Log.warning ).

Example

load( "spine.mat", "X" )
X = X / max( X, [], "all" );
outputFile = "output\xray.jpg";
validExts = ["" ".mat" "image"];
[ isSave, Log ] = isvalidpath( outputFile, "file", validExts );
if isSave
    [ filePath, ~, fileExt ] = fileparts( outputFile );
    if ~isfolder( filePath )
        [ status, msg ] = mkdir( filePath );
        assert( status == 1, ...
            "Could not make output directory:\n -\t%s", msg )
    end
    try
        if strcmp( fileExt, "" ) || strcmp( fileExt, ".mat" )
            save( outputFile, "X" )
        else
            imwrite( X, outputFile )
        end
        fprintf( "Saved patient scan to '%s'.\n", outputFile )
    catch ME
        warning( ME.identifier, ...
            "Patient scan not saved:\n -\t%s", ME.message )
    end
else
    warning( "Patient scan not saved. " + ...
        "outputFile is not a valid.\n\n%s\n", Log.warning )
end

Notes

Created in 2022b. Compatible with MATLAB release 2019b and later. Compatible with all platforms.

Published under MIT License (see LICENSE.txt).

Please cite George Abrahams (GitHub, LinkedIn, Google Scholar).