C#•2y ago

❔ Parsing JSON value with multiple different possibilities

I have a JSON object which can take on one of two different structures

"name": {
  "first": "John",
  "last": "Smith"
}
// or
"name": "John Smith"

"name": {
  "first": "John",
  "last": "Smith"
}
// or
"name": "John Smith"

How would I go about parsing this into an object using STJ? Assume the object to deserialize to is this

record Person(Name Name);
record Name(string First, string Last);

record Person(Name Name);
record Name(string First, string Last);

20 Replies

er🎃•2y ago

You'd want a converter, i assume

Thinker•2y ago

Yeah, guess I should probably invesitgate how to properly write one

er🎃•2y ago

string firstOrFull = reader.GetString();

if (reader.Read()
    && reader.TokenType == JsonTokenType.String)
{
    return new Name(firstOrFull, reader.GetString());
}
else
{
  string[] split = firstOrFull.Split(' ');
  return new Name(split[0], split[1]);
}

string firstOrFull = reader.GetString();

if (reader.Read()
    && reader.TokenType == JsonTokenType.String)
{
    return new Name(firstOrFull, reader.GetString());
}
else
{
  string[] split = firstOrFull.Split(' ');
  return new Name(split[0], split[1]);
}

Thinker•2y ago

hmm

Johnny Rage•2y ago

Luke, use generics!

Thinker•2y ago

idk how generics would help in this situation

CoRoys•2y ago

If the object name contains first and last fields return a Person class; otherwise return a full string (and split them as ero did). Use generics just like Johnny mentioned.

Thinker•2y ago

yeah I've done that and it works however I don't get what you mean by "use generics"

CoRoys•2y ago

https://learn.microsoft.com/en-us/dotnet/csharp/fundamentals/types/generics

Generic classes and methods

Learn about generics. Generic types maximize code reuse, type safety, and performance, and are commonly used to create collection classes.

CoRoys•2y ago

An important concept in deserialisation

Thinker•2y ago

yes I know what generics are

CoRoys•2y ago

So? Use JsonConvert.DeserializeObject<GENERIC_T> to get the return type you want. That's the idea.

Thinker•2y ago

yes? of course, albeit using STJ The question wasn't about how to deserialize JSON, it was about how I'd create a converter for this specific scenario

CoRoys•2y ago

Ah I see

Sossenbinder•2y ago

I assume it's indeed easiest to navigate the JSON with a JsonDocument first and then Deserializing it to your respective type as soon as traversing the JSON got you enough information to figure out what the type is Probably the other alternative would be to do a greedy try-catch wrapped deserialize to both types In case the first one is not compatible it would just throw

CoRoys•2y ago

Or it'd just return null?

Sossenbinder•2y ago

I'm not sure on the spot right now whether it threw or returned null in case the json didn't match the type, I think it throws but would have to check

CoRoys•2y ago

Same

Sossenbinder•2y ago

But I guess other than that, a custom converter would probably not help much since the "converting" part is already covered, your types match the JSON, so there's no need to teach STJ how to parse them Unless you're actually asking how to potentially get both JSON shapes into a single internal type for a Name

Accord•17mo 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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❔ Parsing JSON value with multiple different possibilities