A Hello World Example for JSON

If you change the example slightly, then a JSON object will be delivered.

arangosh> db._routing.save({ 
........>  url: "/hello/json", 
........>  content: { 
........>  contentType: "application/json", 
........>    body: '{"hello" : "world"}'
........>  }
........> });
arangosh> require("internal").reloadRouting()
show execution results

Again check with your browser or cURL http://localhost:8529/hello/json

Depending on your browser and installed add-ons you will either see the JSON object or a download dialog. If your browser wants to open an external application to display the JSON object, you can change the contentType to "text/plain" for the example. This makes it easier to check the example using a browser. Or use curl to access the server.

shell> curl --dump - http://localhost:8529/hello/json

HTTP/1.1 200 OK
content-type: application/json; charset=utf-8
x-content-type-options: nosniff

{ 
  "hello" : "world" 
}










Delivering Content


There are a lot of different ways on how to deliver content. We have already
seen the simplest one, where static content is delivered. The fun, however,
starts when delivering dynamic content.


Static Content


You can specify a body and a content-type.







arangosh> db._routing.save({
........>  url: "/hello/contentType",
........>  content: {
........>    contentType: "text/html",
........>    body: "<html><body>Hello World</body></html>"
........>  }
........> });
arangosh> require("internal").reloadRouting()

show execution results











shell> curl --dump - http://localhost:8529/hello/contentType

HTTP/1.1 200 OK
content-type: text/html
x-content-type-options: nosniff

"Hello World"





















If the content type is text/plain then you can use the short-cut


{ 
  content: "Hello World" 
}



A Simple Action


The simplest dynamic action is:


{ 
  action: { 
    do: "@arangodb/actions/echoRequest" 
  } 
}



It is not advisable to store functions directly in the routing table. It is
better to call functions defined in modules. In the above example the function
can be accessed from JavaScript as:


require("@arangodb/actions").echoRequest



The function echoRequest is pre-defined. It takes the request objects and
echos it in the response.


The signature of such a function must be


function (req, res, options, next)



Examples







arangosh> db._routing.save({ 
........>    url: "/hello/echo",
........>    action: { 
........>    do: "@arangodb/actions/echoRequest" 
........>  } 
........> });

show execution results









Reload the routing and check http:// 127.0.0.1:8529/hello/echo


You should see something like







arangosh> arango.GET("/hello/echo")

show execution results




















The request might contain path, prefix, suffix, and urlParameters
attributes.  path is the complete path as supplied by the user and always
available.  If a prefix was matched, then this prefix is stored in the attribute
prefix and the remaining URL parts are stored as an array in suffix.  If one
or more parameters were matched, then the parameter values are stored in
urlParameters.


For example, if the url description is


{ 
  url: { 
    match: "/hello/:name/:action" 
  } 
}



and you request the path /hello/emil/jump, then the request object
will contain the following attribute


urlParameters: { 
  name: "emil", 
  action: "jump" 
}



Action Controller


As an alternative to the simple action, you can use controllers. A controller is
a module, defines the function get, put, post, delete, head,
patch. If a request of the corresponding type is matched, the function will be
called.


Examples







arangosh> db._routing.save({ 
........>  url: "/hello/echo",
........>  action: { 
........>    controller: "@arangodb/actions/echoController" 
........>  } 
........> });

show execution results









Reload the routing and check http:// 127.0.0.1:8529/hello/echo:







arangosh> arango.GET("/hello/echo")

show execution results





















Prefix Action Controller


The controller is selected when the definition is read. There is a more
flexible, but slower and maybe insecure variant, the prefix controller.


Assume that the url is a prefix match


{ 
  url: { 
    match: /hello/*" 
  } 
}



You can use


{ 
  action: { 
    prefixController: "@arangodb/actions" 
  } 
}



to define a prefix controller. If the URL /hello/echoController is given, then
the module @arangodb/actions/echoController is used.


If you use a prefix controller, you should make certain that no unwanted actions
are available under the prefix.


The definition


{ 
  action: "@arangodb/actions" 
}



is a short-cut for a prefix controller definition.


Function Action


You can also store a function directly in the routing table.


Examples







arangosh> db._routing.save({ 
........>  url: "/hello/echo",
........>  action: { 
........>    callback: "function(req,res) {res.statusCode=200; res.body='Hello'}" 
........>  } 
........> });

show execution results











arangosh> arango.GET("hello/echo")
arangosh> db._query("FOR route IN _routing FILTER route.url == '/hello/echo' REMOVE route in _routing")
[object ArangoQueryCursor, count: 0, cached: false, hasMore: false]
arangosh> require("internal").reloadRouting()










Requests and Responses


The controller must define handler functions which take a request object and
fill the response object.


A very simple example is the function echoRequest defined in the module
@arangodb/actions.


function (req, res, options, next) {
  var result;

  result = { request: req, options: options };

  res.responseCode = exports.HTTP_OK;
  res.contentType = "application/json";
  res.body = JSON.stringify(result);
}



Install it via:







arangosh> db._routing.save({ 
........>  url: "/echo",
........>  action: { 
........>    do: "@arangodb/actions/echoRequest" 
........>  }
........> })

show execution results









Reload the routing and check http:// 127.0.0.1:8529/hello/echo


You should see something like







arangosh> arango.GET("/hello/echo")
arangosh> db._query("FOR route IN _routing FILTER route.url == '/hello/echo' REMOVE route in _routing")
arangosh> require("internal").reloadRouting()

show execution results









You may also pass options to the called function:







arangosh> db._routing.save({ 
........>  url: "/echo",
........>  action: {
........>    do: "@arangodb/actions/echoRequest",
........>    options: { 
........>      "Hello": "World" 
........>    }
........>  } 
........> });

show execution results









You now see the options in the result:







arangosh> arango.GET("/echo")
arangosh> db._query("FOR route IN _routing FILTER route.url == '/echo' REMOVE route in _routing")
arangosh> require("internal").reloadRouting()

show execution results









© ArangoDB - the native multi-model NoSQL database