Building Dynamic Web API Controllers

ASP.NET Boilerplate can automatically generate ASP.NET Web API layer for your application layer. Say that we have an application service as shown below:

public interface ITaskAppService : IApplicationService
{
    GetTasksOutput GetTasks(GetTasksInput input);
    void UpdateTask(UpdateTaskInput input);
    void CreateTask(CreateTaskInput input);
}

And we want to expose this service as a Web API Controller for clients. ASP.NET Boilerplate can automatically and dynamically create a Web API Controller for this application service with a single line of configuration:

DynamicApiControllerBuilder.For<ITaskAppService>("tasksystem/task").Build();

Thats all! An api controller is created in the address '/api/services/tasksystem/task' and all methods are now usable by clients. This configuration should be made in the module initialization.

ITaskAppService is the application service that we want to wrap with an api controller. It is not restricted to application services but this is the conventional and recommended way. "tasksystem/task" is name of the api controller with an arbitrary namespace. You should define at least one-level namespace but you can define more deep namespaces like "myCompany/myApplication/myNamespace1/myNamespace2/myServiceName". '/api/services/' is a prefix for all dynamic web api controllers. So, address of the api controller will be like '/api/services/tasksystem/task' and GetTasks method's address will be '/api/services/tasksystem/task/getTasks'. Method names are converted to camelCase since it's conventional in javascript world.

ForAll Method

We may have many application services in an application and building api controllers one by one may be a tedious and forgettable work. DynamicApiControllerBuilper provides a method to build web api controllers for all application services in one call. Example:

DynamicApiControllerBuilder
    .ForAll<IApplicationService>(Assembly.GetAssembly(typeof(SimpleTaskSystemApplicationModule)), "tasksystem")
    .Build();

ForAll method is generic and accepts an interface. First parameter is an assembly that has classes derived from given interface. Second one is the namespace prefix of services. Say that we have ITaskAppService and IPersonAppService in given assembly. For this configuration, services will be '/api/services/tasksystem/task' and '/api/services/tasksystem/person'. To calculate service name: Service and AppService postfixes and I prefix is removed (for interfaces). Also, service name is converted to camel case. If you don't like this convention, there is a 'WithServiceName' method that you can determine names. Also, There is a Where method to filter services. This can be useful if you will build for all application services except a few one.

Overriding ForAll

We can override configuration after ForAll method. Example:

DynamicApiControllerBuilder
    .ForAll<IApplicationService>(Assembly.GetAssembly(typeof(SimpleTaskSystemApplicationModule)), "tasksystem")
    .Build();

DynamicApiControllerBuilder
    .For<ITaskAppService>("tasksystem/task")
    .ForMethod("CreateTask").DontCreateAction().Build();

In this code, we created dynamic web api controllers for all application services in an assembly. Then overrided configuration for a single application service (ITaskAppService) to ignore CreateTask method.

ForMethods

We can use ForMethods method to better adjust each method while using ForAll method. Example:

DynamicApiControllerBuilder
    .ForAll<IApplicationService>(Assembly.GetExecutingAssembly(), "app")
    .ForMethods(builder =>
    {
        if (builder.Method.IsDefined(typeof(MyIgnoreApiAttribute)))
        {
            builder.DontCreate = true;
        }
    })
    .Build();

In this example, I used a custom attribute (MyIgnoreApiAttribute) to check for all methods and don't create dynamic web api controller actions for those methods marked with that attribute.

Http Verbs

By default, all methods are created as POST. So, a client should send post requests in order to use created web api actions. We can change this behaviour in different ways.

WithVerb Method

We can use WithVerb for a method like that:

DynamicApiControllerBuilder
    .For<ITaskAppService>("tasksystem/task")
    .ForMethod("GetTasks").WithVerb(HttpVerb.Get)
    .Build();

HTTP Attributes

We can add HttpGet, HttpPost... attributes to methods in the service interface:

public interface ITaskAppService : IApplicationService
{
    [HttpGet]
    GetTasksOutput GetTasks(GetTasksInput input);

    [HttpPut]
    void UpdateTask(UpdateTaskInput input);

    [HttpPost]
    void CreateTask(CreateTaskInput input);
}

In order to use these attributes, we should add reference to Microsoft.AspNet.WebApi.Core nuget package from your project.

Naming Convention

Instead of declaring HTTP very for every method, you can use WithConventionalVerbs method as shown below:

DynamicApiControllerBuilder
    .ForAll<IApplicationService>(Assembly.GetAssembly(typeof(SimpleTaskSystemApplicationModule)), "tasksystem")
    .WithConventionalVerbs()
    .Build();

In this case, HTTP verbs are determined by method name prefixes:

• Get: Used if method name starts with 'Get'.
• Put: Used if method name starts with 'Put' or 'Update'.
• Delete: Used if method name starts with 'Delete' or 'Remove'.
• Post: Used if method name starts with 'Post', 'Create' or 'Insert'.
• Patch: Used if method name starts with 'Patch'.
• Otherwise, Post is used as default HTTP verb.

We can override it for a specific method as described before.

API Explorer

All dynamic web api controllers are visible to API explorer by default (They are available in Swagger for example). You can control this behaviour with fluent DynamicApiControllerBuilder API or using RemoteService attribute defined below.

RemoteService Attribute

You can also use RemoteService attribute for any interface or method definition to enable/disable (IsEnabled) dynamic API or API explorer setting (IsMetadataEnabled).

Dynamic Javascript Proxies

You can use the dynamically created web api controller via ajax in javascript. ASP.NET Boilerplate also simplifies this by creating dynamic javascript proxies for dynamic web api controllers. So, you can call a dynamic web api controller's action from javascript as like a function call:

abp.services.tasksystem.task.getTasks({
    state: 1
}).done(function (result) {
    //use result.tasks here...
});

Javascript proxies are created dynamically. You should include the dynamic script to your page before use it:

<script src="/api/AbpServiceProxies/GetAll" type="text/javascript"></script>

Service methods return promise (See jQuery.Deferred). You can register to done, fail, then... callbacks. Service methods use abp.ajax inside. They handle errors and show error messages if needed.

AJAX Parameters

You may want to pass custom ajax parameters to the proxy method. You can pass them as second argument as sown below:

abp.services.tasksystem.task.createTask({
    assignedPersonId: 3,
    description: 'a new task description...'
},{ //override jQuery's ajax parameters
    async: false,
    timeout: 30000
}).done(function () {
    abp.notify.success('successfully created a task!');
});

All parameters of jQuery.ajax are valid here.

In addition to standard jQuery.ajax parameters, you can add abpHandleError: false to AJAX options in order to disable automatic message displaying on error cases.

Single Service Script

'/api/AbpServiceProxies/GetAll' generates all service proxies in one file. You can also generate a sinle service proxy using '/api/AbpServiceProxies/Get?name=serviceName' and include the script to the page as shown below:

<script src="/api/AbpServiceProxies/Get?name=tasksystem/task" type="text/javascript"></script>

Angular Integration

ASP.NET Boilerplate can expose dynamic api controllers as angularjs services. Consider the sample below:

(function() {
    angular.module('app').controller('TaskListController', [
        '$scope', 'abp.services.tasksystem.task',
        function($scope, taskService) {
            var vm = this;
            vm.tasks = [];
            taskService.getTasks({
                state: 0
            }).success(function(result) {
                vm.tasks = result.tasks;
            });
        }
    ]);
})();

We can inject a service using it's name (with namespace). Then we can call it's functions as regular javascript functions. Notice that we registered to success handler (instead of done) since it's like that in angular's $http service. ASP.NET Boilerplate uses $http service of AngularJs. If you want to pass $http configuration, you can pass a configuration object as the last parameter of the service method.

To be able to use auto-generated services, you should include needed scripts to your page:

<script src="~/Abp/Framework/scripts/libs/angularjs/abp.ng.js"></script>
<script src="~/api/AbpServiceProxies/GetAll?type=angular"></script>

Enable/Disable

If you used ForAll method as defined above, the you can use RemoteService attribute to disable it for a service or for method. Use this attribute in the service interface, not in the service class.

Wrapping Results

ASP.NET Boilerplate wraps return values of dynamic Web API actions by AjaxResponse object. See ajax documentation for more information on this wrapping. You can enable/disable wrapping per method or per application service. See this example application service:

public interface ITestAppService : IApplicationService
{
    [DontWrapResult]
    DoItOutput DoIt(DoItInput input);
}

We disabled wrapping for DoIt method. This properties should be declared for interfaces, not implementation classes.

Unwrapping can be useful if you want to more control on exact return values to the client. Especially, disabling it may be needed while working 3rd party client side libraries which can not work with ASP.NET Boilerplate's standard AjaxResponse. In this case, you should also handle exceptions yourself since exception handling will be disabled (DontWrapResult attribute has WrapOnError properties that can be used to enable handling and wrapping for exceptions).

Note: Dynamic javascript proxies can understand if result is unwrapped and run properly in either case.

About Parameter Binding

ASP.NET Boilerplate creates Api Controllers on runtime. So, ASP.NET Web API's model and parameter binding is used to bind model and parameters. You can read it's documentation for more information.

FormUri and FormBody Attributes

FromUri and FromBody attributes can be used in service interface to advanced control on binding.

DTOs vs Primitive Types

We strongly advice to use DTOs as method parameters for application services and web api controllers. But you can also use primitive types (like string, int, bool... or nullable types like int?, bool?...) as service arguments. More than one parameters can be used but only one complex-type parameter is allowed in these parameters (because of restriction of ASP.NET Web API).