sketchfab download throws error if two models have the same name

[fwild]

The problem is in the way we store the models. Right now the identifier is the model name, and if we try to download one model named "Microscope" and then try to download another model with the same name "MicroScope" this will lead to the fact that we will store the second model data and the archive of the first, which leads us to an error when trying to unarchive the archive.

We have some strange logic in the code:

• downloading: We download the model from the sketch fab. unzip it into a folder with local models.
• add it to the activity: we pack the unpacked model back into the archive (if there is no archive) and unzip it again into the folder with the activity data (an error occurs at this stage).

The error thrown is from the archive which we have created ourselves:

Size mismatch between central header(656) and local header(688)

Solution:

• Instead of the name as an identifier you should use the uid of the object.
• the logic needs to be cleaned up and checked (also with a view on performance: couldn't the models be already loaded as invisible, so that they just need to be placed and activated?)

This is the relevant code:

public static async Task LoadModelAsync(ModelPreviewItem modelPreview)
{
    var modelsFolderPath = Path.Combine(Application.persistentDataPath, FOLDER_NAME);
    var archiveUrl = Path.Combine(modelsFolderPath, $"{modelPreview.name}.zip");
    var modelFolder = Path.Combine(modelsFolderPath, modelPreview.name);
    var targetDirectory = Path.Combine(RootObject.Instance.activityManager.ActivityPath, modelPreview.name);
    if (!Directory.Exists(targetDirectory)) Directory.CreateDirectory(targetDirectory);

    // build zip archive, if required (might be slow for big models)
    if (!File.Exists(archiveUrl))
    {
        Debug.Log("model archive not found, taking remedial action...");
        using (var stream = new FileStream(archiveUrl, FileMode.OpenOrCreate))
        using (var zipStream = new ZipOutputStream(stream))
        {
            await ZipUtilities.CompressFolderAsync($"{modelFolder}\\", zipStream);
        }
    }

    // unpack to session folder
    using (var stream = new FileStream(archiveUrl, FileMode.Open))
    {
        await ZipUtilities.ExtractZipFileAsync(stream, targetDirectory);
    }
}

[cawke]

The problem is in the way we store the models. Right now the identifier is the model name, and if we try to download one model named "Microscope" and then try to download another model with the same name "MicroScope" this will lead to the fact that we will store the second model data and the archive of the first, which leads us to an error when trying to unarchive the archive. instead of the name as an identifier you should use the uid of the object.

[fwild]

Moreover: currently there is not way to 'flush' the download folder - the only way to clean up space is to uninstall the app. This needs remediation.