Question

我有这种服务方法：

updateUser(article) {
        this.httpClient
            .put(`articles/${article.id}`, article)
            .pipe(
                map(res => res.response),
                mergeMap(updatedArticle =>
                    this.articlesTagsAPI.someMethod(updatedArticle.id).pipe(
                        map(tags => ({ ...updatedArticle, tags })),
                        article.articleType === 'news'
                            ? mergeMap(() =>
                                  this.articlesTagsAPI.someOtherMethod(updatedArticle.id, article.tags).pipe(
                                      map(() => {
                                          return {
                                              ...updatedArticle,
                                              tags: article.tags
                                          };
                                      })
                                  )
                              )
                            : null
                    )
                )
            );
}

如您所见-我正在尝试添加条件mergeMap（如果条件->则另外调用一个方法）有可能做些什么吗？

因为返回null-不是最好的主意

如果条件无效，应该发生以下情况：

updateUser(article) {
            this.httpClient
                .put(`articles/${article.id}`, article)
                .pipe(
                    map(res => res.response),
                    mergeMap(updatedArticle =>
                        this.articlesTagsAPI.someMethod(updatedArticle.id).pipe(
                            map(tags => ({ ...updatedArticle, tags }))
                        )
                    )
                );
    }

Answer 1

如此非常有用的article中所述，执行此操作的正确方法是添加of指令，以始终在最终订阅中返回Observable的值。

尝试一下：

updateUser(article) {

    this.httpClient
        .put(`articles/${article.id}`, article)
        .pipe(
            map(res => res.response),
            mergeMap(updatedArticle =>
                this.articlesTagsAPI.someMethod(updatedArticle.id).pipe(
                    map(tags => ({ ...updatedArticle, tags })),
                    article.articleType === 'news'
                        ? mergeMap(() =>
                                this.articlesTagsAPI.someOtherMethod(updatedArticle.id, article.tags).pipe(
                                    map(() => {
                                        return {
                                            ...updatedArticle,
                                            tags: article.tags
                                        };
                                    })
                                )
                            )
                        : of(null)
                )
            )
        );
}

Answer 2

尝试一下：

updateUser（文章）{

            buildSettings = {
                ALWAYS_SEARCH_USER_PATHS = NO;
                ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
                CLANG_ENABLE_MODULES = YES;
                CLANG_ENABLE_OBJC_ARC = YES;
                COPY_PHASE_STRIP = NO;
                GCC_DYNAMIC_NO_PIC = NO;
                GCC_OPTIMIZATION_LEVEL = 0;
                GCC_PRECOMPILE_PREFIX_HEADER = YES;
                GCC_PREFIX_HEADER = "MyApp/MyApp-Prefix.pch";
                GCC_THUMB_SUPPORT = NO;
                GCC_VERSION = "";
                INFOPLIST_FILE = "MyApp/MyApp-Info.plist";
                IPHONEOS_DEPLOYMENT_TARGET = 11.0;
                LD_RUNPATH_SEARCH_PATHS = "@executable_path/Frameworks";
                PRODUCT_BUNDLE_IDENTIFIER = io.ionic.starter;
                PRODUCT_NAME = "$(TARGET_NAME)";
                TARGETED_DEVICE_FAMILY = "1,2";
            };
            name = Debug;
        };
        1D6058950D05DD3E006BFB54 /* Release */ = {
            isa = XCBuildConfiguration;
            baseConfigurationReference = 3047A5101AB8059700498E2A /* build-release.xcconfig */;
            buildSettings = {
                ALWAYS_SEARCH_USER_PATHS = NO;
                ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
                CLANG_ENABLE_MODULES = YES;
                CLANG_ENABLE_OBJC_ARC = YES;
                COPY_PHASE_STRIP = YES;
                GCC_PRECOMPILE_PREFIX_HEADER = YES;
                GCC_PREFIX_HEADER = "MyApp/MyApp-Prefix.pch";
                GCC_THUMB_SUPPORT = NO;
                GCC_VERSION = "";
                INFOPLIST_FILE = "MyApp/MyApp-Info.plist";
                IPHONEOS_DEPLOYMENT_TARGET = 11.0;
                LD_RUNPATH_SEARCH_PATHS = "@executable_path/Frameworks";
                PRODUCT_BUNDLE_IDENTIFIER = io.ionic.starter;
                PRODUCT_NAME = "$(TARGET_NAME)";
                TARGETED_DEVICE_FAMILY = "1,2";
            };
            name = Release;
        };
        C01FCF4F08A954540054247B /* Debug */ = {
            isa = XCBuildConfiguration;
            baseConfigurationReference = 3047A5111AB8059700498E2A /* build.xcconfig */;
            buildSettings = {
                ...
                WK_WEB_VIEW_ONLY = 1;
                IPHONEOS_DEPLOYMENT_TARGET = 11.0;
            };
            name = Debug;
        };
        .....

}

RxJS：跳过条件的mergeMap

2 个答案: