Qt Quick 演示 - RESTful API 客户端

如何创建 RESTful API QML 客户端的范例。

This example shows how to create a basic QML RESTful API client with an imaginary color palette service. The application uses RESTful communication with the selected server to request and send data. The REST service is provided as a QML element whose child elements wrap the individual JSON data APIs provided by the server.

Application functionality

The example provides the following basic functionalities:

Select the server to communicate with
List users and colors
Login and logout users
Modify and create new colors

Server selection

At start the application presents the options for the color palette server to communicate with. The predefined options are:

reqres.in , a publicly available REST API test service
Qt-based REST API server example in QtHttpServer

Once selected, the RESTful API client issues a test HTTP GET to the color API to check if the service is accessible.

One major difference between the two predefined API options is that the Qt-based REST API server example is a stateful application which allows modifying colors, whereas the reqres.in is a stateless API testing service. In other words, when using the reqres.in backend, modifying the colors has no lasting impact.

List users and colors

The users and colors are paginated resources on the server-side. This means that the server provides the data in chunks called pages . The UI listing reflects this pagination and views the data on pages.

Viewing the data on UI is done with standard QML views:

ListView {
    id: colorListView
    model: root.colors.data

Where the model is a list of JSON data received from the server.

Logging in

Logging in happens via the login function provided by the login popup:

userMenu.userLoginService.login({"email" : userInfo.modelData.email,
                    "password" : "apassword",
                    "id" : userInfo.modelData.id})

Under the hood the login sends a HTTP POST request. Upon receiving a successful response the authorization token is extracted from the response, which in turn is then used in subsequent HTTP requests which require the token.

Editing colors

Editing and adding new colors is done in a popup:

Note that uploading the color changes to the server requires that a user has logged in.

REST implementation

The example illustrates one way to compose a REST service from individual resource elements. In this example the resources are the paginated user and color resources plus the login service. The resource elements are bound together by the base URL (server URL) and the shared network access manager.

The basis of the REST service is the RestService element whose children items compose the actual service:

RestService {
    id: paletteService
    PaginatedResource {
        id: users
        path: "users"
    }
    PaginatedResource {
        id: colors
        path: "unknown"
    }
    BasicLogin {
        id: colorLogin
        loginPath: "login"
        logoutPath: "logout"
    }
}

Upon instantiation the RestService element loops its children elements and sets them up to use the same network access manager. This way the individual resources share the same access details such as the server URL and authorization token.

The actual communication is done with a rest access manager which implements some convenience functionality to deal specifically with HTTP REST APIs and effectively deals with sending and receiving the QNetworkRequest and QNetworkReply as needed.

运行范例

要运行范例从 Qt Creator ，打开欢迎模式，然后选择范例从范例。更多信息，拜访构建和运行范例 .

范例工程 @ code.qt.io