How to wait for the complete execution of a IEnumerator function in C#?

Question

I want to get the result of a webrequest in another function but unfortunately the variable of the webrequest stays empty, because the webrequest isn't already xecuted when I call the variable. I call the OpenFile Function which calls the GetText one:

private string[] m_fileContent;

public void OpenFile(string filePath)
    {
        StartCoroutine(GetText());
        Console.Log(m_fileContent);// is empty
    }

IEnumerator GetText()
    {
        UnityWebRequest www = UnityWebRequest.Get("http://...");
        yield return www.SendWebRequest();

        if (www.isNetworkError || www.isHttpError)
        {
            Debug.Log(www.error);
        }
        else
        {
            m_fileContent = www.downloadHandler.text.Split('\n');
            Debug.Log("here" + m_fileContent);//data printed ok

        }
    }

So the GetText function prints the text but in the OpenFile function the variable m_fileContent is empty.

Any ideas how to solve this?

Thank you!

Answer 1

The issue

The line

Console.Log(m_fileContent);

is reached immediately and doesn't wait until the Coroutine finished.

Solution

Use an Action<string[]> and pass in a callback like e.g.

public void OpenFile(string filePath, Action<string[]> onTextResult)
{
    // pass in a callback that handles the result string
    StartCoroutine(GetText(onTextResult));
}

IEnumerator GetText(Action<string[]> onResult)
{
    UnityWebRequest www = UnityWebRequest.Get("http://...");
    yield return www.SendWebRequest();

    if (www.isNetworkError || www.isHttpError)
    {
        Debug.Log(www.error);
    }
    else
    {
        var fileContent = www.downloadHandler.text.Split('\n');

        // Invoke the passed action and pass in the file content 
        onResult?.Invoke(fileContent);
    }
}

And then call it like

// Either as lambda expression
OpenFile("some/file/path", fileContent => {
    Console.Log(fileContent);
});

// or using a method
OpenFile("some/file/path", OnFileResult);

...

private void OnFileResult(string[] fileContent)
{
    Console.Log(fileContent);
}