// todo: directives
public static async Task <IEnumerable <FieldSelection> > CollectFields(
VariableValues variableValues,
IDictionary <string, InputType> variableTypes,
GraphQLObject gqlObject,
IEnumerable <Selection> selectionSet,
IEnumerable <FragmentDefinition> fragments,
List <GraphQLError> errors,
ILogger logger,
ExceptionFilter exceptionFilter,
CancellationToken token)
{
var result = new List <FieldSelection>();
foreach (var selection in selectionSet)
{
switch (selection)
{
case Ast.Field field:
{
IValueAccessor valueAccessor;
var selectionFieldSelectionSet = Enumerable.Empty <FieldSelection>();
if (!gqlObject.Fields.TryGetValue(field.Name, out var objectField))
{
valueAccessor = new NullValueAccessor();
errors.Add(new GraphQLError(
$"Invalid field '{field.Name}' specified on '{gqlObject.GetTypeName()}'.",
new[] { field.Location }));
}
else
{
var fieldArguments = field.Arguments ?? Enumerable.Empty <Argument>();
if (!ValidateArguments(variableTypes, gqlObject, errors, objectField, fieldArguments))
{
valueAccessor = new NullValueAccessor();
}
else
{
var astFieldArguments = fieldArguments
.ToDictionary(x => x.Name);
var argumentValues = new Dictionary <string, object>();
var hasErrors = false;
foreach (var argument in objectField.Arguments)
{
var hasArgument = astFieldArguments.TryGetValue(argument.Key, out var argumentValue);
var value = hasArgument
? argumentValue.Value.GetValue(variableValues)
: new Optional();
var variable = argumentValue?.Value as Variable;
var preamble = variable != null
? $"Variable '${variable.Name}'"
: $"Argument '{argument.Key}'";
var locations = new List <GraphQLLocation>();
if (variable != null)
{
locations.Add(variable.Location);
}
if (hasArgument)
{
locations.Add(argumentValue.Location);
}
// need to be able to get a type adapter from an AST node
//var target = variable != null
// ? new BoundGraphQLTypeAdapter(null, variableTypes[variable.Name].GetTypeAdapter())
// : argument.Value;
var target = argument.Value;
var coercionResult = target.CoerceInput(argument.Key, value.Value);
if (coercionResult.Errors != null && coercionResult.Errors.Any())
{
errors.AddRange(coercionResult.Errors
.Select(x => new GraphQLError(
$"{preamble} expected value of type '{argument.Value.GetTypeDescription()}' but got: {value}. {x}",
locations,
null,
new Dictionary <string, object>
{
{
"InputError",
new
{
Input = x.Name,
Reason = "Coercion",
}
},
}))
.ToList()
);
hasErrors = true;
}
else
{
argumentValues.Add(argument.Key, coercionResult.Value);
}
}
if (hasErrors)
{
valueAccessor = new NullValueAccessor();
}
else
{
try
{
valueAccessor = await objectField.Resolve(argumentValues, token);
selectionFieldSelectionSet = valueAccessor.GraphQLType.Unwrap() is GraphQLObject graphQLObject
? await CollectFields(
variableValues,
variableTypes,
graphQLObject,
field.SelectionSet,
fragments,
errors,
logger,
exceptionFilter,
token)
: null;
}
catch (GraphQLException ex)
{
errors.AddRange(ex.Errors);
valueAccessor = new NullValueAccessor();
}
catch (Exception ex)
{
if (ex is TargetInvocationException || ex is AggregateException)
{
ex = ex.InnerException ?? ex;
}
if (ex is GraphQLException gex)
{
errors.AddRange(gex.Errors);
}
else
{
if (exceptionFilter != null && await exceptionFilter.HandleExceptionAsync(ex))
{
throw;
}
if (logger != null)
{
logger.LogError(ex, "Error resolving field in FieldCollector");
}
errors.Add(new GraphQLError(
"Internal server error",
null,
null,
null));
}
valueAccessor = new NullValueAccessor();
}
}
var fieldSelection = new FieldSelection(
field.Name,
field.Alias,
field.Arguments,
field.Directives,
selectionFieldSelectionSet,
objectField,
field.Location,
valueAccessor
);
var index = result
.FindIndex(x => x.Alias == field.Alias && x.Name == field.Name);
if (index >= 0)
{
result[index] = result[index].MergeWith(fieldSelection);
}
else
{
result.Add(fieldSelection);
}
}
}
}
break;
case FragmentSpread fragmentSpread:
{
var fragment = fragments
.Where(x => x.FragmentName == fragmentSpread.FragmentName)
.FirstOrDefault() ?? throw new InvalidOperationException("Invalid fragment");
if (fragment.TypeCondition == gqlObject.GetTypeName())
{
var fields = await CollectFields(
variableValues,
variableTypes,
gqlObject,
fragment.SelectionSet,
fragments,
errors,
logger,
exceptionFilter,
token
);
foreach (var field in fields)
{
var index = result
.FindIndex(x => x.Alias == field.Alias && x.Name == field.Name);
if (index >= 0)
{
result[index] = result[index].MergeWith(field);
}
else
{
result.Add(field);
}
}
}
}
break;
case InlineFragment inlineFragment:
{
if (inlineFragment.TypeCondition == gqlObject.GetTypeName())
{
var fields = await CollectFields(
variableValues,
variableTypes,
gqlObject,
inlineFragment.SelectionSet,
fragments,
errors,
logger,
exceptionFilter,
token
);
foreach (var field in fields)
{
var index = result
.FindIndex(x => x.Alias == field.Alias && x.Name == field.Name);
if (index >= 0)
{
result[index] = result[index].MergeWith(field);
}
else
{
result.Add(field);
}
}
}
}
break;
}
}
return(result);
}
private static bool ValidateArguments(IDictionary <string, InputType> variableTypes, GraphQLObject gqlObject, List <GraphQLError> errors, Schema.Field objectField, IEnumerable <Argument> fieldArguments)
{
var valid = true;
foreach (var arg in fieldArguments)
{
var inputType = arg.Value.GetType(variableTypes);
if (!objectField.Arguments.TryGetValue(arg.Name, out var graphQLType))
{
valid = false;
errors.Add(new GraphQLError(
$"Unknown argument '{arg.Name}' on field '{objectField.Name}' of type '{gqlObject.GetTypeName()}'.",
new[] { arg.Location }));
}
else if (arg.Value is Variable variable)
{
var inputTypeDescription = inputType.GetTypeDescription();
var graphQLTypeDescription = graphQLType.GetTypeDescription();
if (!inputTypeDescription.CanBeDownCastTo(graphQLTypeDescription))
{
valid = false;
errors.Add(new GraphQLError(
$"Variable '${arg.Name}' of type '{inputTypeDescription}' used in position expecting type '{graphQLTypeDescription}'.",
new[] { variable.Location, arg.Location }));
}
}
// todo: validate non-variable values
}
return(valid);
}
public static Expression <Func <TObject, DataReference, T> > VisitValueAccessors <TObject, T>(GraphQLObject parent, Expression <Func <TObject, T> > expression)
where TObject : GraphQLObject
{
var visitor = new SchemaExpressionVisitor(parent);
var result = Expression.Lambda <Func <TObject, DataReference, T> >(expression.Body, expression.Parameters[0], visitor.DataReferenceParameter);
return((Expression <Func <TObject, DataReference, T> >)visitor.Visit(result));
}
