Model Validation

OttoTheGeek will examine your model types and build GraphQL types for each of them. For classes, Otto will build OBJECT types where the public properties of your classes will become fields on the GraphQL type. For scalar values, Otto will map to appropriate GraphQL types, such as INT, BOOL, etc. according to the table at the bottom of this file.

For values that aren’t seen as scalars, OttoTheGeek requires you to configure how these fields are resolved. If any field in any type in your model hasn’t been configured, building a schema from your OttoModel<TQuery>-derived model class will throw an UnableToResolveException that will give you the information about which class and which property was left unconfigured.

C# to GraphQL .Net Scalar Type Mapping

The following table shows the default scalar types that OttoTheGeek recognizes. See below for custom scalar types.

C# Type	GraphQL .Net Type
string	NonNullGraphType<StringGraphType>
int	NonNullGraphType<IntGraphType>
long	NonNullGraphType<IntGraphType>
double	NonNullGraphType<FloatGraphType>
float	NonNullGraphType<FloatGraphType>
decimal	NonNullGraphType<DecimalGraphType>
bool	NonNullGraphType<BooleanGraphType>
DateTime	NonNullGraphType<DateGraphType>
DateTimeOffset	NonNullGraphType<DateTimeOffsetGraphType>
Guid	NonNullGraphType<IdGraphType>
short	NonNullGraphType<ShortGraphType>
ushort	NonNullGraphType<UShortGraphType>
ulong	NonNullGraphType<ULongGraphType>
uint	NonNullGraphType<UIntGraphType>
TimeSpan	NonNullGraphType<TimeSpanGraphType>
long?	IntGraphType
int?	IntGraphType
long?	IntGraphType
double?	FloatGraphType
float?	FloatGraphType
decimal?	DecimalGraphType
bool?	BooleanGraphType
DateTime?	DateGraphType
DateTimeOffset?	DateTimeOffsetGraphType
Guid?	IdGraphType
short?	ShortGraphType
ushort?	UShortGraphType
ulong?	ULongGraphType
uint?	UIntGraphType
TimeSpan?	TimeSpanGraphType

If you’d like to add a custom scalar type, you can use the .ScalarType<,>() method on SchemaBuilder. For instance, if you have a class FancyInt that you’d like to use as a scalar property on your models, use something similar to the following:

public class Model : OttoModel<Query>
{
    protected override SchemaBuilder ConfigureSchema(SchemaBuilder builder)
    {
        return builder
            .ScalarType<FancyInt, FancyIntConverter>()
            // other config probably
    }
}

public struct FancyInt
{
    public int Value { get; }
    private FancyInt(int value)
    {
        Value = value;
    }
    public static FancyInt FromInt(int value)
    {
        return new FancyInt(value);
    }
}


public sealed class FancyIntConverter : ScalarTypeConverter<FancyInt>
{
    public override string Convert(FancyInt value)
    {
        return $"**{value.Value}**";
    }

    public override FancyInt Parse(string value)
    {
        var trimmed = value.Trim('*');
        return FancyInt.FromInt(int.Parse(trimmed));
    }
}