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Query 库将内容从上游分发到多个下游 WordPress 站点

将内容从上游分发到多个下游 WordPress 站点

假设某媒体公司拥有一个面向不同地区的 WordPress 站点网络，每篇新闻文章仅在适合该地区时才会发布到对应站点。

对于这种情况，实现以下架构是合理的：

  • 所有内容发布到（并在其中编辑）单个上游 WordPress 站点，该站点作为内容的唯一可信来源
  • 将适合的内容分发到（但不在其中编辑）各地区的下游 WordPress 站点

此 Query 满足该架构要求，上游 WordPress 站点需要激活相关的 Gato GraphQL 扩展，而下游站点只需安装免费的 Gato GraphQL 插件即可。

该 Query 在上游 WordPress 站点上执行，使用文章别名作为跨站点的通用标识符，将已更新文章的内容同步到相关下游站点。

其中包含事务处理逻辑：无论是因为 HTTP 请求失败（例如服务器宕机）还是因为 GraphQL Query 返回错误（例如不存在具有所提供别名的文章），只要任何下游站点的更新失败，就会在所有下游站点上回滚该 mutation。

请注意，下游域名通过文章的元属性 "downstream_domains" 提供，其中包含文章需要分发到的下游站点域名数组。如果该元属性不存在，则会从 wp_options 表中获取选项 "downstream_domains"，其中包含所有下游域名的列表。

然后使用相同的 $username 和 $userPassword 登录每个下游站点，并执行 mutation 以更新文章内容。如果任何下游站点返回错误，则在所有下游站点上回滚该 mutation。

此 Query 要求端点启用嵌套 Mutation。

query InitializeDynamicVariables
  @configureWarningsOnExportingDuplicateVariable(enabled: false)
{
  initVariablesWithFalse: _echo(value: false)
    @export(as: "requestProducedErrors")
    @export(as: "anyErrorProduced")
    @export(as: "hasDownstreamDomains")
    @remove
}
 
query GetCustomDownstreamDomains($postSlug: String!)
  @depends(on: "InitializeDynamicVariables")
{
  post(by: { slug: $postSlug }, status: any)
    @fail(
      message: "There is no post in the upstream site with the provided slug"
      data: {
        slug: $postSlug
      }
    )
  {
    customDownstreamDomains: metaValues(key: "downstream_domains")
      @export(as: "downstreamDomains")
 
    hasDefinedCustomDownstreamDomains: _notNull(value: $__customDownstreamDomains)
      @export(as: "hasDefinedCustomDownstreamDomains")
      @remove
 
    hasCustomDownstreamDomains: _notEmpty(value: $__customDownstreamDomains)
      @export(as: "hasDownstreamDomains")
  }
 
  isMissingPostInUpstream: _isNull(value: $__post)
    @export(as: "isMissingPostInUpstream")
}
 
query GetAllDownstreamDomains
  @depends(on: "GetCustomDownstreamDomains")
  @skip(if: $isMissingPostInUpstream)
  @skip(if: $hasDefinedCustomDownstreamDomains)
{
  allDownstreamDomains: optionValues(name: "downstream_domains")
    @export(as: "downstreamDomains")
 
  hasAllDownstreamDomains: _notEmpty(value: $__allDownstreamDomains)
    @export(as: "hasDownstreamDomains")
}
 
############################################################
# (By default) Append "/graphql" to the domain, to point
# to that site's GraphQL single endpoint
############################################################
query ExportDownstreamGraphQLEndpointsAndQuery(
  $endpointPath: String! = "/graphql"
)
  @depends(on: "GetAllDownstreamDomains")
  @skip(if: $isMissingPostInUpstream)
  @include(if: $hasDownstreamDomains)
{
  downstreamGraphQLEndpoints: _echo(value: $downstreamDomains)
    @underEachArrayItem(
      passValueOnwardsAs: "domain"
    )
      @strAppend(string: $endpointPath)
    @export(as: "downstreamGraphQLEndpoints")
 
  query: _echo(value: """
    
mutation LoginUserAndUpdatePost(
  $username: String!
  $userPassword: String!
  $postSlug: String!
  $postContent: String!
) {
  loginUser(by: {
    credentials: {
      usernameOrEmail: $username,
      password: $userPassword
    }
  }) {
    userID
  }
 
  post(by: { slug: $postSlug }, status: any)
    @fail(
      message: "There is no post in the downstream site with the provided slug"
      data: {
        slug: $postSlug
      }
    )
  {
    update(input: {
      contentAs: { html: $postContent },
    }) {
      status
      errors {
        __typename
        ...on ErrorPayload {
          message
        }
      }
      post {
        slug
        rawContent
      }
    }
  }
}
 
    """
  )
    @export(as: "query")
    @remove
}
 
query ExportSendGraphQLHTTPRequestInputs(
  $username: String!
  $userPassword: String!
  $postSlug: String!
  $newPostContent: String!
)
  @depends(on: "ExportDownstreamGraphQLEndpointsAndQuery")
  @skip(if: $isMissingPostInUpstream)
  @include(if: $hasDownstreamDomains)
{
  sendGraphQLHTTPRequestInputs: _echo(value: $downstreamGraphQLEndpoints)
    @underEachArrayItem(
      passValueOnwardsAs: "endpoint"
    )
      @applyField(
        name: "_echo",
        arguments: {
          value: {
            endpoint: $endpoint,
            query: $query,
            variables: [
              {
                name: "username",
                value: $username
              },
              {
                name: "userPassword",
                value: $userPassword
              },
              {
                name: "postSlug",
                value: $postSlug
              },
              {
                name: "postContent",
                value: $newPostContent
              }
            ]
          }
        },
        setResultInResponse: true
      )
    @export(as: "sendGraphQLHTTPRequestInputs")
    @remove
}
 
query SendGraphQLHTTPRequests
  @depends(on: "ExportSendGraphQLHTTPRequestInputs")
  @skip(if: $isMissingPostInUpstream)
  @include(if: $hasDownstreamDomains)
{
  downstreamGraphQLResponses: _sendGraphQLHTTPRequests(
    inputs: $sendGraphQLHTTPRequestInputs
  )
    @export(as: "downstreamGraphQLResponses")
 
  requestProducedErrors: _isNull(value: $__downstreamGraphQLResponses)
    @export(as: "requestProducedErrors")
    @export(as: "anyErrorProduced")
    @remove
}
 
query ExportGraphQLResponsesHaveErrors
  @depends(on: "SendGraphQLHTTPRequests")
  @skip(if: $isMissingPostInUpstream)
  @skip(if: $requestProducedErrors)
  @include(if: $hasDownstreamDomains)
{
  graphQLResponsesHaveErrors: _echo(value: $downstreamGraphQLResponses)    
    # Check if any GraphQL response has the "errors" entry
    @underEachArrayItem(
      passValueOnwardsAs: "response"
      affectDirectivesUnderPos: [1, 2]
    )
      @applyField(
        name: "_propertyIsSetInJSONObject"
        arguments: {
          object: $response
          by: {
            key: "errors"
          }
        }
        setResultInResponse: true
      )
    @export(as: "graphQLResponsesHaveErrors")
    @remove
}
 
query ValidateGraphQLResponsesHaveErrors
  @depends(on: "ExportGraphQLResponsesHaveErrors")
  @skip(if: $isMissingPostInUpstream)
  @skip(if: $requestProducedErrors)
  @include(if: $hasDownstreamDomains)
{
  anyGraphQLResponseHasErrors: _or(values: $graphQLResponsesHaveErrors)
    @export(as: "anyErrorProduced")
    @remove
}
 
query ExportRevertGraphQLHTTPRequestInputs(
  $username: String!
  $userPassword: String!
  $postSlug: String!
  $previousPostContent: String!
)
  @depends(on: "ValidateGraphQLResponsesHaveErrors")
  @include(if: $hasDownstreamDomains)
  @include(if: $anyErrorProduced)
{
  revertGraphQLHTTPRequestInputs: _echo(value: $downstreamGraphQLEndpoints)
    @underEachArrayItem(
      passValueOnwardsAs: "endpoint"
    )
      @applyField(
        name: "_echo",
        arguments: {
          value: {
            endpoint: $endpoint,
            query: $query,
            variables: [
              {
                name: "username",
                value: $username
              },
              {
                name: "userPassword",
                value: $userPassword
              },
              {
                name: "postSlug",
                value: $postSlug
              },
              {
                name: "postContent",
                value: $previousPostContent
              }
            ]
          }
        },
        setResultInResponse: true
      )
    @export(as: "revertGraphQLHTTPRequestInputs")
    @remove
}
 
query RevertGraphQLHTTPRequests
  @depends(on: "ExportRevertGraphQLHTTPRequestInputs")
  @skip(if: $isMissingPostInUpstream)
  @include(if: $hasDownstreamDomains)
  @include(if: $anyErrorProduced)
{
  revertGraphQLResponses: _sendGraphQLHTTPRequests(
    inputs: $sendGraphQLHTTPRequestInputs
  )
}
 
query DistributeContentFromUpstreamToMultipleDownstreamWPSites
  @depends(on: "RevertGraphQLHTTPRequests")
{
  id @remove
}