private static void AddFieldWithIdArgumentIfExists <TContextType>(MappedSchemaProvider <TContextType> schema, Type contextType, Field fieldProp)
{
if (!fieldProp.Resolve.Type.IsEnumerableOrArray())
{
return;
}
var schemaType = schema.Type(fieldProp.ReturnTypeClrSingle);
// Find the first field named "id" or "<fieldProp.Name>Id" to turn into a field with arguments
var idFieldDef = schemaType.GetFields().FirstOrDefault(f => f.Name.ToLower() == "id" || f.Name.ToLower() == $"{fieldProp.Name.ToLower()}id");
if (idFieldDef == null)
{
return;
}
// Save a little bit of typing and clean things up.
var idFieldName = idFieldDef.Name;
// We need to build an anonymous type with id = RequiredField<idFieldDef.Resolve.Type>()
// Resulting lambda is (a, p) => a.Where(b => b.Id == p.Id).First()
// This allows us to "insert" .Select() (and .Include()) before the .First()
var requiredFieldType = typeof(RequiredField <>).MakeGenericType(idFieldDef.Resolve.Type);
var fieldNameAndType = new Dictionary <string, Type> {
{ idFieldName, requiredFieldType }
};
var argTypes = LinqRuntimeTypeBuilder.GetDynamicType(fieldNameAndType);
var argTypesValue = argTypes.GetTypeInfo().GetConstructors()[0].Invoke(new Type[0]);
var argTypeParam = Expression.Parameter(argTypes);
Type arrayContextType = schema.Type(fieldProp.ReturnTypeClrSingle).ContextType;
var arrayContextParam = Expression.Parameter(arrayContextType);
var ctxId = Expression.PropertyOrField(arrayContextParam, $"{char.ToUpper(idFieldName[0])}{idFieldName.Substring(1)}");
Expression argId = Expression.PropertyOrField(argTypeParam, idFieldName);
argId = Expression.Property(argId, "Value"); // call RequiredField<>.Value to get the real type without a convert
var idBody = Expression.MakeBinary(ExpressionType.Equal, ctxId, argId);
var idLambda = Expression.Lambda(idBody, new[] { arrayContextParam });
Expression body = ExpressionUtil.MakeExpressionCall(new[] { typeof(Queryable), typeof(Enumerable) }, "Where", new Type[] { arrayContextType }, fieldProp.Resolve, idLambda);
body = ExpressionUtil.MakeExpressionCall(new[] { typeof(Queryable), typeof(Enumerable) }, "FirstOrDefault", new Type[] { arrayContextType }, body);
var contextParam = Expression.Parameter(contextType);
var lambdaParams = new[] { contextParam, argTypeParam };
body = new ParameterReplacer().ReplaceByType(body, contextType, contextParam);
var selectionExpression = Expression.Lambda(body, lambdaParams);
var name = fieldProp.Name.Singularize();
if (name == null)
{
// If we can't singularize it just use the name plus something as GraphQL doesn't support field overloads
name = $"{fieldProp.Name}";
}
var field = new Field(name, selectionExpression, $"Return a {fieldProp.ReturnTypeClrSingle} by its Id", fieldProp.ReturnTypeClrSingle, argTypesValue);
schema.AddField(field);
}
/// <summary>
/// Given the type TContextType recursively create a query schema based on the public properties of the object.
/// </summary>
/// <param name="autoCreateIdArguments">If True, automatically create a field for any root array thats context object contains an Id property. I.e. If Actor has an Id property and the root TContextType contains IEnumerable<Actor> Actors. A root field Actor(id) will be created.</param>
/// <typeparam name="TContextType"></typeparam>
/// <returns></returns>
public static MappedSchemaProvider <TContextType> FromObject <TContextType>(bool autoCreateIdArguments = true, bool authCreateEnumTypes = true)
{
var schema = new MappedSchemaProvider <TContextType>();
var contextType = typeof(TContextType);
var rootFields = AddFieldsFromObjectToSchema <TContextType>(contextType, schema);
foreach (var f in rootFields)
{
if (autoCreateIdArguments)
{
// add non-pural field with argument of ID
AddFieldWithIdArgumentIfExists(schema, contextType, f);
}
schema.AddField(f);
}
return(schema);
}
private static void AddFieldWithIdArgumentIfExists <TContextType>(MappedSchemaProvider <TContextType> schema, Type contextType, Field fieldProp)
{
if (!fieldProp.Resolve.Type.IsEnumerable())
{
return;
}
var schemaType = schema.Type(fieldProp.ReturnSchemaType);
var idFieldDef = schemaType.GetFields().FirstOrDefault(f => f.Name == "Id");
if (idFieldDef == null)
{
return;
}
// We need to build an anonymous type with id = RequiredField<idFieldDef.Resolve.Type>()
// Resulting lambda is (a, p) => a.Where(b => b.Id == p.Id).First()
// This allows us to "insert" .Select() (and .Include()) before the .First()
var requiredFieldType = typeof(RequiredField <>).MakeGenericType(idFieldDef.Resolve.Type);
var fieldNameAndType = new Dictionary <string, Type> {
{ "id", requiredFieldType }
};
var argTypes = LinqRuntimeTypeBuilder.GetDynamicType(fieldNameAndType);
var argTypesValue = argTypes.GetTypeInfo().GetConstructors()[0].Invoke(new Type[0]);
var argTypeParam = Expression.Parameter(argTypes);
Type arrayContextType = schema.Type(fieldProp.ReturnSchemaType).ContextType;
var arrayContextParam = Expression.Parameter(arrayContextType);
var ctxId = Expression.PropertyOrField(arrayContextParam, "Id");
Expression argId = Expression.PropertyOrField(argTypeParam, "id");
argId = Expression.Property(argId, "Value"); // call RequiredField<>.Value to get the real type without a convert
var idBody = Expression.MakeBinary(ExpressionType.Equal, ctxId, argId);
var idLambda = Expression.Lambda(idBody, new[] { arrayContextParam });
Expression body = ExpressionUtil.MakeExpressionCall(new[] { typeof(Queryable), typeof(Enumerable) }, "Where", new Type[] { arrayContextType }, fieldProp.Resolve, idLambda);
body = ExpressionUtil.MakeExpressionCall(new[] { typeof(Queryable), typeof(Enumerable) }, "FirstOrDefault", new Type[] { arrayContextType }, body);
var contextParam = Expression.Parameter(contextType);
var lambdaParams = new[] { contextParam, argTypeParam };
body = new ParameterReplacer().ReplaceByType(body, contextType, contextParam);
var selectionExpression = Expression.Lambda(body, lambdaParams);
var field = new Field(fieldProp.Name.Singularize(), selectionExpression, $"Return {fieldProp.ReturnSchemaType} by Id", fieldProp.ReturnSchemaType, argTypesValue);
schema.AddField(field);
}