• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1# Calling an ArkTS Method with Return Value of a promise Using Node-API
2
3## When to Use
4You can call the ArkTS APIs, which return a promise, in the created ArkTS runtime environment as follows:
5
6## Calling an ArkTS Method Asynchronously
7Use Node-API to call the ArkTS method that returns a promise in C++.
8Handle the promise object: Bind the promise object to a C++ callback to process the result returned asynchronously.
9Convert the data type: In the callback, convert the JavaScript (JS) result to the data that can be used by C++.
10Conduct thread-safe processing to ensure security of cross-thread operations.
11
12### Sample Code
13- Register the module.
14    ```c++
15    #include "hilog/log.h"
16    #include "napi/native_api.h"
17    #include <napi/common.h>
18    #include <pthread.h>
19
20    // Callback for processing a resolved promise.
21    static napi_value ResolvedCallback(napi_env env, napi_callback_info info)
22    {
23        size_t argc = 1;
24        napi_value args[1];
25        napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);
26
27        int result;
28        napi_get_value_int32(env, args[0], &result);
29        OH_LOG_INFO(LOG_APP, "Promise resolved with result:%{public}d", result);
30        return nullptr;
31    }
32
33    // Callback for processing a rejected promise.
34    static napi_value RejectedCallback(napi_env env, napi_callback_info info)
35    {
36        size_t argc = 1;
37        napi_value args[1];
38        napi_get_cb_info(env, info, &argc, args, nullptr, nullptr);
39
40        napi_value error;
41        napi_coerce_to_string(env, args[0], &error);
42        char errorMsg[1024];
43        size_t len;
44        napi_get_value_string_utf8(env, error, errorMsg, sizeof(errorMsg), &len);
45        OH_LOG_ERROR(LOG_APP, "Promise rejected with error:%{public}s", errorMsg);
46        return nullptr;
47    }
48
49    static napi_value CallArkTSAsync(napi_env env, napi_callback_info info)
50    {
51        size_t argc = 1;
52        napi_value argv[1] = { nullptr };
53        napi_get_cb_info(env, info, &argc, argv, nullptr, nullptr);
54        napi_value promise = nullptr;
55        napi_call_function(env, nullptr, argv[0], 0, nullptr, &promise);
56
57        napi_value thenFunc = nullptr;
58        if (napi_get_named_property(env, promise, "then", &thenFunc) != napi_ok) {
59            return nullptr;
60        }
61
62        napi_value onResolve = nullptr;
63        napi_value onReject = nullptr;
64        napi_create_function(env, "onResolve", NAPI_AUTO_LENGTH, ResolvedCallback, nullptr, &onResolve);
65        napi_create_function(env, "onReject", NAPI_AUTO_LENGTH, RejectedCallback, nullptr, &onReject);
66        napi_value argv1[2] = {onResolve, onReject};
67        napi_call_function(env, promise, thenFunc, 2, argv1, nullptr);
68
69        return nullptr;
70    }
71
72    // Register the module.
73    EXTERN_C_START
74    static napi_value Init(napi_env env, napi_value exports)
75    {
76        napi_property_descriptor desc[] = {
77            {"callArkTSAsync", nullptr, CallArkTSAsync, nullptr, nullptr, nullptr, napi_default, nullptr}
78        };
79        napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
80        return exports;
81    }
82    EXTERN_C_END
83
84    static napi_module nativeModule = {
85        .nm_version = 1,
86        .nm_flags = 0,
87        .nm_filename = nullptr,
88        .nm_register_func = Init,
89        .nm_modname = "entry",
90        .nm_priv = nullptr,
91        .reserved = { 0 },
92    };
93
94    extern "C" __attribute__((constructor)) void RegisterEntryModule()
95    {
96        napi_module_register(&nativeModule);
97    }
98    ```
99
100- Declare APIs.
101    ```ts
102    // index.d.ts
103    export const callArkTSAsync: (func: Function) => object;
104    ```
105
106- Configure compile settings.
1071. Configure the **CMakeLists.txt** file as follows:
108    ```
109    // CMakeLists.txt
110    # the minimum version of CMake.
111    cmake_minimum_required(VERSION 3.4.1)
112    project(myapplication)
113
114    set(NATIVERENDER_ROOT_PATH ${CMAKE_CURRENT_SOURCE_DIR})
115
116    if(DEFINED PACKAGE_FIND_FILE)
117        include(${PACKAGE_FIND_FILE})
118    endif()
119
120    include_directories(${NATIVERENDER_ROOT_PATH}
121                        ${NATIVERENDER_ROOT_PATH}/include)
122    add_library(entry SHARED hello.cpp)
123    target_link_libraries(entry PUBLIC libace_napi.z.so)
124    ```
1252. Add the following to the **build-profile.json5** file of the project.
126    ```json
127    {
128        "buildOption" : {
129            "arkOptions" : {
130                "runtimeOnly" : {
131                    "sources": [
132                        "./src/main/ets/pages/ObjectUtils.ets"
133                    ]
134                }
135            }
136        }
137    }
138    ```
139- ArkTS sample code
140    ```ts
141    // index.ets
142    import testNapi from 'libentry.so'
143
144    export function SetTimeout() : Promise<number> {
145        return new Promise((resolve) => {
146            setTimeout(() => {
147                resolve(42);
148            }, 1000)
149        })
150    }
151    testNapi.callArkTSAsync(SetTimeout);
152    ```
153