Web API Basics

Web API Basics

Learn More @ http://www.learnnowonline.com
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Objectives


Objectives
• See how REST and web services can be
used to access data


Objectives
used to access data
• Build your ﬁrst Web API service


Objectives
used to access data
• Use Web API naming conventions for
routing


Objectives
used to access data
• Use Web API naming conventions for
routing
• Modify your service for basic CRUD
operations


Agenda


Agenda
• What Is ASP.NET Web API?


Agenda
• Create Your First Web API Service


Agenda
• Web API Routing


Agenda
• Web API Routing
• Create a Web API Service for CRUD
Operations


Agenda
• Web API Routing
• Create a Web API Service for CRUD
Operations
• Filtering Data with Parameters


What Is ASP.NET Web API?


• Next iteration of WCF REST


• Incorporated into ASP.NET MVC 4


• Incorporated into ASP.NET MVC 4
• Framework for developing REST
oriented services


REST


REST
• Uses HTTP protocols


REST
• URLs and methods


REST
• Accessible from a wide variety of
clients


REST
clients
• HTTP methods:


REST
clients
• HTTP methods:
• GET


REST
clients
• HTTP methods:
• GET
• POST


REST
clients
• HTTP methods:
• GET
• POST
• PUT


GET


GET
• Primarily just a URL making a simple
request for a resource, e.g., a web page


GET
• Response is sent back


GET
• Additional information is put in a query
string


GET
string
• Generally used to Select data


GET
string
• Selecting all:


GET
string
• Selecting all:
http://www.root.com/products/


GET
string
• Selecting all:
http://www.root.com/products/
• Selecting one:


POST


POST
• Sends collection of name-value pairs
along with the request


POST
• Commonly used with forms on the web


POST
• Used to add new resources (Insert)


POST
• Used to add new resources (Insert)
• Should return an appropriate HTTP
success code


PUT


PUT
• Used to store a resource at the
supplied URL


PUT
• Used to store a resource at the
supplied URL
• Generally used for Editing existing
resources


DELETE


DELETE
• Used for deleting resources


DELETE
• Used for deleting resources
• Should return an appropriate HTTP
code


Create Your First Web API


• Create a repository


• Create an API controller to use the
repository


• Create an API controller to use the
repository
• Try it out in a browser


Web API Routing


Web API Routing
• Interpretation of URLs by the server to
decide what code should handle the
request


Web API Routing
request
• Operates similarly to ASP.NET MVC
routing


Web API Routing
request
• Operates similarly to ASP.NET MVC
routing
• Actions determined by HTTP method
used


Default Mapping


Default Mapping
• Conﬁgured in Global.asax


Default Mapping
• Uses “api” as URL segment


Default Mapping
• Adds word “Controller” to the
controller part of URL


Default Mapping
• Looks for action that begins with the
HTTP method


Default Mapping
• Looks for action that begins with the
HTTP method
• Additional URL parameters are mapped
as action parameters


Alternative Routing


Alternative Routing
• Rarely necessary for most Web API
services


Alternative Routing
• Rarely necessary for most Web API
services
• Several options to change URL routing


HTTP Method Attributes


• Very similar to ASP.NET MVC


• Use attributes to bind HTTP methods
to speciﬁc actions


[HttpGet]


[HttpGet]
[HttpPost]


[HttpGet]
[HttpPost]
[HttpPut]


[HttpGet]
[HttpPost]
[HttpPut]
[HttpDelete]


AcceptVerbs Attribute


• Also used on actions


• Specify HTTP methods as strings


• Specify HTTP methods as strings
• Especially useful for atypical HTTP
methods


Action Names in the URL


• Makes URLs route identically to
ASP.NET MVC


ASP.NET MVC
• Must change routeTemplate in
Global.asax


ASP.NET MVC
• Must change routeTemplate in
Global.asax
• Must also add HTTP method attributes
to actions


Removing Actions from


• Used when a resource’s URL would
trigger an action, but this is not
desired


• Used when a resource’s URL would
trigger an action, but this is not
desired
• Use the NonAction attribute on the
method


Create a Web API Service for
CRUD Operations


CRUD Operations

• Create – POST


CRUD Operations

• Create – POST
• Read – GET


CRUD Operations

• Create – POST
• Read – GET
• Update – PUT


CRUD Operations

• Create – POST
• Read – GET
• Update – PUT
• Delete – DELETE


CRUD Operations

• Create – POST
• Read – GET
• Update – PUT
• Basic functionality that most services
will have


CRUD Operations

• Create – POST
• Read – GET
• Update – PUT
• Basic functionality that most services
will have
• Try it out!

Filtering Data with


Filtering Data with
• Uses the OData protocol


Filtering Data with
• Special query strings can be used to:


Filtering Data with
• Filter


Filtering Data with
• Filter
• Page


Filtering Data with
• Filter
• Page
• Sort


Filtering Data with
• Filter
• Page
• Sort
• And more…


Filter


Filter
• Condition that evaluates to true or
false


Filter
false
• Uses OData-speciﬁc keywords


Filter
false
• Uses OData-speciﬁc keywords
• Must be sendable in a URL


Order By


Order By
• Speciﬁes the sort order of returned
data


Order By
data
• Can sort by multiple properties


Order By
data
• Can sort by multiple properties
• Can specify ASC and DESC sorting


Paging


Paging
• Done by using $skip and $top


Paging
• $skip passes over a number of records


Paging
• $skip should be set to: page number *
page size


Paging
page size
• $top selects a certain number to return


Paging
page size
• $top selects a certain number to return
• $top should be set to page size


There’s More


There’s More
• There are other OData query strings


There’s More
• Other query keywords for $ﬁlter


There’s More
• Other query keywords for $ﬁlter
• www.odata.org


Learn More!


Learn More!
• This is an excerpt from a larger course. Visit
www.learnnowonline.com for the full details!


Web API Basics

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