A Delphi REST client API to consume REST services written in any programming language.
The API it is designed to work with Delphi 7 or later. Newer versions takes advantage of Generics Methods.
There are a IHttpConnection interface to abstract the real Http conection. This interface currently have two implementations, using Indy 10, WinHTTP and WinInet.
Indy 9 does not handles HTTP response codes correctly, then if you are using Delphi 7, you must update your indy library to version 10 or use WinHttp (recommended). To disable indy support comment the compiler directive {.$DEFINE USE_INDY} in DelphiRest.inc file.
The objects are transmitted in JSON format. To function properly, the object must be declared as follows, with public fields.
TPerson = class(TObject)
public
(* Reflect the server side object field names, for Java must be case-sensitive *)
id: Integer;
name: String;
email: String;
(* Static constructor *)
class function NewFrom(Id: Integer; Name, EMail: String): TPerson;
end;See more details about serialization here: Serialization
Note that all code below assume you have installed the component in your IDE and dropped the RestClient component on a form or data module, but of course you can also create the component directly in your code.
- GET
var
vList : TList<TPerson>;
begin
vList := RestClient.Resource('http://localhost:8080/java-rest-server/rest/persons')
.Accept(RestUtils.MediaType_Json)
.Get<TList<TPerson>>();- GET ONE
var
vPerson : TPerson;
begin
vPerson := RestClient.Resource('http://localhost:8080/java-rest-server/rest/person/1')
.Accept(RestUtils.MediaType_Json)
.Get<TPerson>();- POST
var
vPerson : TPerson;
begin
vPerson := TPerson.NewFrom(123, 'Fabricio', '[email protected]');
RestClient.Resource('http://localhost:8080/java-rest-server/rest/person')
.Accept(RestUtils.MediaType_Json)
.ContentType(RestUtils.MediaType_Json)
.Post<TPerson>(vPerson);- PUT
var
vPerson : TPerson;
begin
vPerson := //Load person
vPerson.Email := '[email protected]';
RestClient.Resource('http://localhost:8080/java-rest-server/rest/person')
.Accept(RestUtils.MediaType_Json)
.ContentType(RestUtils.MediaType_Json)
.Put<TPerson>(vPerson);- DELETE
var
vPerson : TPerson;
begin
vPerson := //Load person
RestClient.Resource('http://localhost:8080/java-rest-server/rest/person')
.Accept(RestUtils.MediaType_Json)
.ContentType(RestUtils.MediaType_Json)
.Delete(vPerson);- GET AS DATASET
The fields need be predefined.
var
vDataSet: TClientDataSet;
begin
vDataSet := TClientDataSet.Create(nil);
try
TDataSetUtils.CreateField(vDataSet, ftInteger, 'id');
TDataSetUtils.CreateField(vDataSet, ftString, 'name', 100);
TDataSetUtils.CreateField(vDataSet, ftString, 'email', 100);
vDataSet.CreateDataSet;
RestClient.Resource(CONTEXT_PATH 'persons')
.Accept(RestUtils.MediaType_Json)
.GetAsDataSet(vDataSet);
finally
vDataSet.Free;
end;- GET AS DYNAMIC DATASET
The fields are created dynamically according to the returned content.
var
vDataSet: TDataSet;
begin
vDataSet := RestClient.Resource(CONTEXT_PATH 'persons')
.Accept(RestUtils.MediaType_Json)
.GetAsDataSet();
try
//Do something
finally
vDataSet.Free;
end;- ASYNC REQUESTS
//Implement OnAsyncRequestProcess event to allow cancelling a request or update the UI
RestClient.OnAsyncRequestProcess :=
procedure(var Cancel: Boolean)
begin
Cancel := True; // Set cancel to true to abort the request
end;
// This will raise an EAbort if the request is canceled
RestClient.Resource(CONTEXT_PATH 'async')
.Accept('text/plain')
.Async
.GET();NOTE: Async request is only supported for
WinHTTP. Any thought about how to implement this feature forIndyandWinInetare welcome.
- MULTIPART/FORM-DATA
Send forms with file attachments is possible by declaring a class that represents the form fields and inherits from TMultiPartFormData.
TRequestData = class(TMultiPartFormData)
name: string;
ticket_number: integer;
signed_contract: TMultiPartFormAttachment;
end; Request := TRequestData.Create;
Request.name := 'Fernando';
Request.ticket_number := 123;
Request.signed_contract := TMultiPartFormAttachment.Create('c:\contract.txt', 'text/plain', 'contract.txt');
Result := RestClient.Resource(URL).Post(Request);RestClient supports HTTP Basic authentication. You can set credentials using the SetCredentials method before making the first request:
RestClient.SetCredentials('username', 'password');You can set it once and it will be used for every request.
To skip certificate validation set VerifyCert to false.
RestClient.VerifyCert := false;Indy note: Certificate validation is not yet supported with
Indy. Certificates will not be validated! Any thought about how to implement this feature forIndyare welcome.
- hrmRaise (default)
Raises an exception after the event. - hrmIgnore
Ignore the error. No exception will be raised after the event. - hrmRetry
Retries the request.
Triggered for all status codes equal or above 400.
The following example will ignore the status code 404. This will result in an empty response (nil for objects). You'll have to check if your objects has been assigned after every request.
AHTTPError.ErrorMessage contains the content of the response.
You can deserialize this to display your own error message (see RestJsonUtils.TJsonUtil).
restclient := TRestClient.Create(self);
restclient.ConnectionType := hctWinINet;
restclient.OnError := RestError;
procedure Tdm.RestError(ARestClient: TRestClient; AResource: restclient.TResource;
AMethod: TRequestMethod; AHTTPError: EHTTPError;
var ARetryMode: THTTPRetryMode);
begin
ARetryMode := hrmRaise;
if AHTTPError.ErrorCode = 404 then
ARetryMode := hrmIgnore;
end;The following example will retry the request forever. If you want it to only retry for at limited time, you'll have to implement that counter your self.
restclient := TRestClient.Create(self);
restclient.ConnectionType := hctWinINet;
restclient.OnConnectionLost := RestConnectionLost;
procedure Tdm.RestConnectionLost(AException: Exception; var ARetryMode: THTTPRetryMode);
begin
ARetryMode := hrmRetry;
sleep(1000);
end;The java project is only for test purpose and has built using Maven and Jersey, so it's needed have installed the JRE 6 (Java Runtime Environment) and Maven 2 to build and run the application. The Maven bin directory must be included in Windows Path environment variable.
After install Java and Maven just run 'start-java-server.bat' to start the application and 'stop-java-server.bat' to shut down them.
When 'start-java-server.bat' is first run maven dependencies will be downloaded, and it may take a while.
The Delphi REST client API is released under version 2.0 of the Apache License.
