/// <summary>
/// Adds middleware specified by its type to the list of delegates that will be applied to the schema when invoking <see cref="IFieldMiddlewareBuilder.ApplyTo(ISchema)"/>.
/// <br/><br/>
/// Middleware will be created using the DI container obtained from the <see cref="Schema"/>.
/// </summary>
/// <param name="builder">Interface for connecting middlewares to a schema.</param>
/// <param name="middleware">Middleware type.</param>
/// <returns>Reference to the same <see cref="IFieldMiddlewareBuilder"/>.</returns>
public static IFieldMiddlewareBuilder Use(this IFieldMiddlewareBuilder builder, System.Type middleware)
{
if (!typeof(IFieldMiddleware).IsAssignableFrom(middleware))
{
throw new ArgumentException($"Field middleware of type '{middleware.FullName}' must implement the {nameof(IFieldMiddleware)} interface", nameof(middleware));
}
return(builder.Use((schema, next) =>
{
if (schema == null)
{
throw new InvalidOperationException("Schema is null. Schema required for resolving middlewares from DI container.");
}
// Not an ideal solution, but at least it allows to work with custom schemas which are not inherited from Schema type
if (!(schema is IServiceProvider provider))
{
throw new NotSupportedException($"'{schema.GetType().FullName}' should implement 'IServiceProvider' interface for resolving middlewares.");
}
var instance = (IFieldMiddleware)provider.GetService(middleware);
if (instance == null)
{
throw new InvalidOperationException($"Field middleware of type '{middleware.FullName}' must be registered in the DI container.");
}
return context => instance.Resolve(context, next);
}));
}
public static IFieldMiddlewareBuilder Use(this IFieldMiddlewareBuilder builder, System.Type middleware)
{
return(builder.Use(next =>
{
var methods = middleware.GetMethods(BindingFlags.Instance | BindingFlags.Public);
var invokeMethods = methods.Where(m => string.Equals(m.Name, InvokeMethodName, StringComparison.Ordinal)).ToArray();
if (invokeMethods.Length > 1)
{
throw new InvalidOperationException($"There should be only a single method named {InvokeMethodName}. Middleware actually has {invokeMethods.Length} methods.");
}
if (invokeMethods.Length == 0)
{
throw new InvalidOperationException($"Could not find a method named {InvokeMethodName}. Middleware must have a public instance method named {InvokeMethodName}.");
}
var methodInfo = invokeMethods[0];
if (!typeof(Task <object>).IsAssignableFrom(methodInfo.ReturnType))
{
throw new InvalidOperationException($"The {InvokeMethodName} method should return a Task<object>.");
}
var parameters = methodInfo.GetParameters();
if (parameters.Length != 2 || parameters[0].ParameterType != typeof(ResolveFieldContext) || parameters[1].ParameterType != typeof(FieldMiddlewareDelegate))
{
throw new InvalidOperationException($"The {InvokeMethodName} method of middleware should take a parameter of type {nameof(ResolveFieldContext)} as the first parameter and a parameter of type {nameof(FieldMiddlewareDelegate)} as the second parameter.");
}
var instance = Activator.CreateInstance(middleware);
return context => (Task <object>)methodInfo.Invoke(instance, new object[] { context, next });
}));
}
/// <summary>
/// Applies all delegates specified by the middleware builder to the schema.
/// <br/><br/>
/// When applying to the schema, modifies the resolver of each field of each graph type adding required behavior.
/// Therefore, as a rule, this method should be called only once - during schema initialization.
/// </summary>
public void ApplyMiddleware(IFieldMiddlewareBuilder fieldMiddlewareBuilder)
{
var transform = (fieldMiddlewareBuilder ?? throw new ArgumentNullException(nameof(fieldMiddlewareBuilder))).Build();
// allocation free optimization if no middlewares are defined
if (transform != null)
{
ApplyMiddleware(transform);
}
}
/// <summary> /// Adds middleware specified by its type to the list of delegates that will be applied to the schema when invoking <see cref="IFieldMiddlewareBuilder.ApplyTo(ISchema)"/>. /// <br/><br/> /// Middleware will be created using the DI container obtained from the <see cref="Schema"/>. /// </summary> /// <typeparam name="T">Middleware type.</typeparam> /// <param name="builder">Interface for connecting middlewares to a schema.</param> /// <returns>Reference to the same <see cref="IFieldMiddlewareBuilder"/>.</returns> public static IFieldMiddlewareBuilder Use <T>(this IFieldMiddlewareBuilder builder) where T : IFieldMiddleware => Use(builder, typeof(T));
/// <summary> /// Adds the specified delegate to the list of delegates that will be applied to the schema when invoking <see cref="IFieldMiddlewareBuilder.ApplyTo(ISchema)"/>. /// <br/><br/> /// This is a compatibility shim when compiling delegates without schema specified. /// </summary> /// <param name="builder">Interface for connecting middlewares to a schema.</param> /// <param name="middleware">Middleware delegate.</param> /// <returns>Reference to the same <see cref="IFieldMiddlewareBuilder"/>.</returns> public static IFieldMiddlewareBuilder Use(this IFieldMiddlewareBuilder builder, Func <FieldMiddlewareDelegate, FieldMiddlewareDelegate> middleware) => builder.Use((_, next) => middleware(next));
/// <summary> /// Adds middleware to the list of delegates that will be applied to the schema when invoking <see cref="IFieldMiddlewareBuilder.ApplyTo(ISchema)"/>. /// </summary> /// <param name="builder">Interface for connecting middlewares to a schema.</param> /// <param name="middleware">Middleware instance.</param> /// <returns>Reference to the same <see cref="IFieldMiddlewareBuilder"/>.</returns> public static IFieldMiddlewareBuilder Use(this IFieldMiddlewareBuilder builder, IFieldMiddleware middleware) => builder.Use(next => context => middleware.Resolve(context, next));
public static IFieldMiddlewareBuilder Use <T>(this IFieldMiddlewareBuilder builder)
{
return(Use(builder, typeof(T)));
}
/// <summary>
/// Adds middleware specified by its type to the list of delegates that will be applied to the schema when invoking <see cref="ApplyTo(ISchema)"/>.
/// <br/><br/>
/// Middleware will be created using the DI container obtained from the <see cref="Schema"/>.
/// </summary>
/// <param name="builder">Interface for connecting middlewares to a schema.</param>
/// <param name="middleware">Middleware type.</param>
/// <returns>Reference to the same <see cref="IFieldMiddlewareBuilder"/>.</returns>
public static IFieldMiddlewareBuilder Use(this IFieldMiddlewareBuilder builder, System.Type middleware)
{