C#•15mo ago

❔ JSON serialization nullable warnings (best approach?)

Kind of have a "best approach" question for the following:

using System.Text.Json;

class FileVerification
{
    private readonly string quackenFilePath = @"C:\Users\maske\Documents\dev\CSharp\TelegramBots\quacken.json";

    private readonly JsonSerializerOptions _options = new()
    {
        PropertyNameCaseInsensitive = true
    };
    public List<QuackenJson> JsonReadWithSystemText()
    {
        using FileStream json = File.OpenRead(quackenFilePath);
        List<QuackenJson> token = JsonSerializer.Deserialize<List<QuackenJson>>(json, _options)!;
        return token;
    }
}

using System.Text.Json;

class FileVerification
{
    private readonly string quackenFilePath = @"C:\Users\maske\Documents\dev\CSharp\TelegramBots\quacken.json";

    private readonly JsonSerializerOptions _options = new()
    {
        PropertyNameCaseInsensitive = true
    };
    public List<QuackenJson> JsonReadWithSystemText()
    {
        using FileStream json = File.OpenRead(quackenFilePath);
        List<QuackenJson> token = JsonSerializer.Deserialize<List<QuackenJson>>(json, _options)!;
        return token;
    }
}

Would you make it nullable using ? or ?? in the appropriate spots, or (in this particular case) since I know the value will never be null, would you do as I have and use ! to suppress the warning?

7 Replies

ero•15mo ago

It would only ever return null if the contents of the quacken.json file were literally just

null

null

If you know that's never the case, I'd suppress it with ! A more proper way would likely be ?? new() But that crosses the territory of inappropriately handling null inputs and hiding said handling away from whoever uses it The most proper way would obviously be to make the return type nullable But now you have some options and some whoopie

MaeFireOP•15mo ago

So the two good options of these three would be either what I did above or

    public List<QuackenJson>? JsonReadWithSystemText()
    {
        using FileStream json = File.OpenRead(quackenFilePath);
        List<QuackenJson>? token = JsonSerializer.Deserialize<List<QuackenJson>>(json, _options);
        return token;
    }

    public List<QuackenJson>? JsonReadWithSystemText()
    {
        using FileStream json = File.OpenRead(quackenFilePath);
        List<QuackenJson>? token = JsonSerializer.Deserialize<List<QuackenJson>>(json, _options);
        return token;
    }

I think this is what you meant by making the return type nullable, right?

ero•15mo ago

Mhm

MaeFireOP•15mo ago

Awesome. Thank you for the insight. I was not aware of the ?? new() hiding the handling away, so I'll just try to keep in mind to either suppress or make it into a nullable type(preferably the latter) ⭐

JakenVeina•15mo ago

if you really don't like Deserialize<>()! you can always do Deserialize<>() ?? throw new InvalidOperationException() one could argue that's the most "proper", even if it's an exception that should never occur as it fails early

ero•15mo ago

I would perhaps choose FormatException

Accord•15mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ JSON serialization nullable warnings (best approach?)