Moving a file in AssetPostprocessor.OnPreprocessAsset()

Unity Engine
1

I’ve got some tool-generated files that are coming into Unity, and one of the file types needs to be renamed as it’s coming in (just adding a “.txt” to the path name). I’m running the following code in an asset pre-processor:

void OnPreprocessAsset() {
    if (assetPath.EndsWith(".foo")) {
        File.Move(assetPath, assetPath + ".txt");
        AssetDatabase.Refresh();
    }

    return;
}

However, when I import the files, I get the following error:

My guess is that the asset importer is operating on the original file, and when I move that file, it throws the error because it loses the reference to the original. The “AssetDatabase.Refresh();” call was added later, but doesn’t seem to have any effect.

Is there a proper way to rename a file in an asset pre-processor, and have the new file processed right away, and/or avoid this error when Unity tries to continue processing a now-nonexistent file?

2

Hey @nickfourtimes1 , here is come documentation on importing assets into Unity. Hope this helps!

3

The problem isn’t so much with getting the files into the project – they’re already in the directory. What I want to do is rename an asset in an AssetPostprocessor.OnPreprocessAsset() call.

I can get to the point of identifying the right assets for renaming, but when I perform the rename on the OS level, the asset processor throws the “missing file” error from the original post.

4

Just tried moving the code into AssetPostprocessor.OnPostProcessAsset(), and doing the work in the post-processor does work. I do force an AssetDatabase.Refresh() after moving the file, to make sure the new asset is properly reimported. This doesn’t necessarily answer the question of how to rename a file during pre-processing, though.

5

Well maybe I was hallucinating because I could swear that latter approach with OnPostprocessAssset() worked, but looking at the documentation page, no such method exists. Weird.

Anyway, I did manage to do things without crashing the pre-processor by copying the file in the pre-process, and then deleting the original in the post-processor, like so:

void OnPreprocessAsset() {
    if (assetPath.EndsWith(".foo")) {
        File.Copy(assetPath, assetPath + ".txt");
        AssetDatabase.ImportAsset(assetPath + ".txt");
    }
    return;
}


static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths) {
    foreach (var path in importedAssets) {
        if (path.EndsWith(".foo")) {
            File.Delete(path);
            AssetDatabase.Refresh();
        }
    }

    return;
}
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