Tutorial del esquema
Tutorial del esquemaLección 29: Importando una entrada desde otro sitio WordPress

Lección 29: Importando una entrada desde otro sitio WordPress

Esta lección del tutorial demuestra cómo podemos mantener sitios WordPress sincronizados, importando una entrada desde algún sitio WordPress a nuestro sitio WordPress local.

Consulta GraphQL para importar una entrada desde otro sitio WordPress

La consulta GraphQL de abajo se conecta al endpoint GraphQL de un sitio web upstream, obtiene los datos para una entrada específica, y la importa localmente. El plugin Gato GraphQL (versión gratuita) debe estar instalado también en el sitio web upstream.

(Si Gato GraphQL no está instalado en el sitio upstream, la consulta puede adaptarse para conectarse a sus endpoints de la API REST de WP en su lugar.)

Los recursos referenciados en la entrada deben todos existir localmente:

  • El autor
  • La imagen destacada (si la hay)
  • Las categorías
  • (Las etiquetas también, sin embargo si éstas aún no existen, se crean junto con la entrada, así que no es un problema)

Como identificador común para recursos entre los sitios upstream y local, usamos:

  • Slugs para categorías, etiquetas y elementos multimedia
  • Usernames para usuarios

Si alguno de los recursos no existe en el sitio local, la consulta GraphQL imprime un error y detiene la importación.

query InitializeDynamicVariables
  @configureWarningsOnExportingDuplicateVariable(enabled: false)
{
  initVariablesWithFalse: _echo(value: false)
    @export(as: "requestProducedErrors")
    @export(as: "responseHasErrors")
    @export(as: "postIsMissing")
    @export(as: "postHasAuthor")
    @export(as: "postHasFeaturedImage")
    @export(as: "postHasCategories")
    @export(as: "postHasTags")
    @remove
 
  initVariablesWithNull: _echo(value: null)
    @export(as: "existingAuthorUsername")
    @export(as: "existingFeaturedImageSlug")
    @export(as: "featuredImageMutationInput")
    @remove
 
  initVariablesWithEmptyArray: _echo(value: [])
    @export(as: "existingCategorySlugs")
    @export(as: "existingTagSlugs")
    @remove
}
 
query CheckIfPostExistsLocally($postSlug: String!)
  @depends(on: "InitializeDynamicVariables")
{
  localPost: post(
    by: { slug: $postSlug }
    status: any
  ) {
    id
  }
 
  postAlreadyExists: _notNull(value: $__localPost)
    @export(as: "postAlreadyExists")
}
 
query FailIfPostAlreadyExistsLocally($postSlug: String!)
  @depends(on: "CheckIfPostExistsLocally")
  @include(if: $postAlreadyExists)
{
  errorMessage: _sprintf(
    string: "Post with slug '%s' already exists locally",
    values: [$postSlug]
  ) @remove
 
  _fail(
    message: $__errorMessage
    data: {
      slug: $postSlug
    }
  ) @remove
 
  createPost: _echo(value: null)
}
 
query ConnectToGraphQLAPI(
  $upstreamServerGraphQLEndpointURL: String!
  $postSlug: String!
)
  @depends(on: "FailIfPostAlreadyExistsLocally")
  @skip(if: $postAlreadyExists)
{
  externalData: _sendGraphQLHTTPRequest(input:{
    endpoint: $upstreamServerGraphQLEndpointURL,
    query: """
    
query GetPost($postSlug: String!) {
  post(by: { slug: $postSlug }) {
    id
    slug
    rawTitle
    rawContent
    rawExcerpt
    author {
      id
      username
    }
    featuredImage {
      id
      slug
    }
    categories {
      id
      slug
    }
    tags {
      id
      slug
    }
  }
}
 
    """,
    variables: [
      {
        name: "postSlug",
        value: $postSlug
      }
    ]
  })
    @export(as: "externalData")
 
  requestProducedErrors: _isNull(value: $__externalData)
    @export(as: "requestProducedErrors")
    @remove
}
 
query ValidateResponse
  @depends(on: "ConnectToGraphQLAPI")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
{
  responseHasErrors: _propertyIsSetInJSONObject(
    object: $externalData
    by: {
      key: "errors"
    }
  )
    @export(as: "responseHasErrors")
    @remove
 
  postExists: _propertyIsSetInJSONObject(
    object: $externalData
    by: {
      path: "data.post"
    }
  )
    @remove
    
  postIsMissing: _not(value: $__postExists)
    @export(as: "postIsMissing")
    @remove
}
 
query FailIfResponseHasErrors
  @depends(on: "ValidateResponse")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $postIsMissing)
  @include(if: $responseHasErrors)
{
  errors: _objectProperty(
    object: $externalData,
    by: {
      key: "errors"
    }
  ) @remove
 
  _fail(
    message: "Executing the GraphQL query against the upstream webserver produced error(s)"
    data: {
      errors: $__errors
    }
  ) @remove
 
  createPost: _echo(value: null)
}
 
query FailIfPostNotExists($postSlug: String!)
  @depends(on: "FailIfResponseHasErrors")
  @skip(if: $requestProducedErrors)
  @include(if: $postIsMissing)
{
  errorMessage: _sprintf(
    string: "There is no post with slug '%s' in the origin",
    values: [$postSlug]
  ) @remove
 
  _fail(
    message: $__errorMessage
    data: {
      slug: $postSlug
    }
  ) @remove
  
  createPost: _echo(value: null)
}
 
query ExportInputs
  @depends(on: "FailIfPostNotExists")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $responseHasErrors)
  @skip(if: $postIsMissing)
{
  postData: _objectProperty(
    object: $externalData,
    by: { path: "data.post" }
  ) @remove
 
  postTitle: _objectProperty(
    object: $__postData,
    by: { key: "rawTitle" }
  )
    @export(as: "postTitle")
    @remove
 
  postContent: _objectProperty(
    object: $__postData,
    by: { key: "rawContent" }
  )
    @export(as: "postContent")
    @remove
 
  postExcerpt: _objectProperty(
    object: $__postData,
    by: { key: "rawExcerpt" }
  )
    @export(as: "postExcerpt")
    @remove
 
  postAuthorUsername: _objectProperty(
    object: $__postData,
    by: { key: "author" }
  )
    @passOnwards(
      as: "author"
    )
    @applyField(
      name: "_notNull",
      arguments: {
        value: $author
      },
      passOnwardsAs: "hasAuthor"
    )
    @if(condition: $hasAuthor)
      @applyField(
        name: "_objectProperty",
        arguments: {
          object: $author,
          by: { key: "username" }
        },
        setResultInResponse: true
      )
    @export(as: "postAuthorUsername")
    @remove
 
  postHasAuthor: _notNull(
    value: $__postAuthorUsername
  )
    @export(as: "postHasAuthor")
    @remove
 
  postFeaturedImageSlug: _objectProperty(
    object: $__postData,
    by: { key: "featuredImage" }
  )
    @passOnwards(
      as: "featuredImage"
    )
    @applyField(
      name: "_notNull",
      arguments: {
        value: $featuredImage
      },
      passOnwardsAs: "hasFeaturedImage"
    )
    @if(condition: $hasFeaturedImage)
      @applyField(
        name: "_objectProperty",
        arguments: {
          object: $featuredImage,
          by: { key: "slug" }
        },
        setResultInResponse: true
      )
    @export(as: "postFeaturedImageSlug")
    @remove
 
  postHasFeaturedImage: _notNull(
    value: $__postFeaturedImageSlug
  )
    @export(as: "postHasFeaturedImage")
    @remove
 
  postCategorySlugs: _objectProperty(
    object: $__postData,
    by: { key: "categories" }
  )
    @underEachArrayItem(
      passValueOnwardsAs: "category"
    )
      @applyField(
        name: "_objectProperty"
        arguments: {
          object: $category,
          by: {
            key: "slug"
          }
        }
        setResultInResponse: true
      )
    @export(as: "postCategorySlugs")
    @remove
 
  postHasCategories: _notEmpty(
    value: $__postCategorySlugs
  )
    @export(as: "postHasCategories")
    @remove
 
  postTagSlugs: _objectProperty(
    object: $__postData,
    by: { key: "tags" }
  )
    @underEachArrayItem(
      passValueOnwardsAs: "tag"
    )
      @applyField(
        name: "_objectProperty"
        arguments: {
          object: $tag,
          by: {
            key: "slug"
          }
        }
        setResultInResponse: true
      )
    @export(as: "postTagSlugs")
    @remove
 
  postHasTags: _notEmpty(
    value: $__postTagSlugs
  )
    @export(as: "postHasTags")
    @remove
}
 
query ExportExistingResources
  @depends(on: "ExportInputs")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $responseHasErrors)
  @skip(if: $postIsMissing)
{
  existingAuthorByUsername: user(by: { username: $postAuthorUsername })
    @include(if: $postHasAuthor)
  {
    id
    username @export(as: "existingAuthorUsername")
  }
 
  existingFeaturedImageBySlug: mediaItem(by: { slug: $postFeaturedImageSlug })
    @include(if: $postHasFeaturedImage)
  {
    id
    slug @export(as: "existingFeaturedImageSlug")
  }
 
  existingCategoriesBySlug: postCategories(filter: { slugs: $postCategorySlugs })
    @include(if: $postHasCategories)
  {
    id
    slug @export(as: "existingCategorySlugs", type: LIST)
  }
 
  existingTagsBySlug: postTags(filter: { slugs: $postTagSlugs })
    @include(if: $postHasTags)
  {
    id
    slug @export(as: "existingTagSlugs", type: LIST)
  }
}
 
query ExportMissingResources
  @depends(on: "ExportExistingResources")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $responseHasErrors)
  @skip(if: $postIsMissing)
{
  isAuthorMissing: _notEquals(
    value1: $postAuthorUsername,
    value2: $existingAuthorUsername
  ) @export(as: "isAuthorMissing")
  
  isFeaturedImageMissing: _notEquals(
    value1: $postFeaturedImageSlug,
    value2: $existingFeaturedImageSlug
  ) @export(as: "isFeaturedImageMissing")
 
  missingCategorySlugs: _arrayDiff(
    arrays: [$postCategorySlugs, $existingCategorySlugs]
  ) @export(as: "missingCategorySlugs")
  areCategoriesMissing: _notEmpty(
    value: $__missingCategorySlugs
  ) @export(as: "areCategoriesMissing")
 
  # missingTagSlugs: _arrayDiff(
  #   arrays: [$postTagSlugs, $existingTagSlugs]
  # ) @export(as: "missingTagSlugs")
  # areTagsMissing: _notEmpty(
  #   value: $__missingTagSlugs
  # ) @export(as: "areTagsMissing")
 
  isAnyResourceMissing: _or(
    values: [
      $__isAuthorMissing,
      $__isFeaturedImageMissing,
      $__areCategoriesMissing,
      # $__areTagsMissing,
    ]
  ) @export(as: "isAnyResourceMissing")
}
 
query FailIfAnyResourceIsMissing
  @depends(on: "ExportMissingResources")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $postIsMissing)
  @skip(if: $responseHasErrors)
  @include(if: $isAnyResourceMissing)
{
  performingValidations: id
    @if(condition: $isAuthorMissing)
      @fail(
        message: "Author is missing in local site"
        data: {
          missingAuthorByUsername: $postAuthorUsername
        }
        condition: ALWAYS
      )
    @if(condition: $isFeaturedImageMissing)
      @fail(
        message: "Featured image is missing in local site"
        data: {
          missingFeaturedImageBySlug: $postFeaturedImageSlug
        }
        condition: ALWAYS
      )
    @if(condition: $areCategoriesMissing)
      @fail(
        message: "Categories are missing in local site"
        data: {
          missingCategoriesBySlug: $missingCategorySlugs
        }
        condition: ALWAYS
      )
    # @if(condition: $areTagsMissing)
    #   @fail(
    #     message: "Tags are missing in local site"
    #     data: {
    #       missingTagBySlug: $missingTagSlugs
    #     }
    #     condition: ALWAYS
    #   )
  
  createPost: _echo(value: null)
}
 
query ExportMutationInputs
  @depends(on: "FailIfAnyResourceIsMissing")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $responseHasErrors)
  @skip(if: $postIsMissing)
  @skip(if: $isAnyResourceMissing)
{
  featuredImageMutationInput: _echo(value: {
    slug: $postFeaturedImageSlug
  })
    @include(if: $postHasFeaturedImage)
    @export(as: "featuredImageMutationInput")
    @remove
}
 
mutation ImportPost(
  $postSlug: String!
)
  @depends(on: "ExportMutationInputs")
  @skip(if: $postAlreadyExists)
  @skip(if: $requestProducedErrors)
  @skip(if: $responseHasErrors)
  @skip(if: $postIsMissing)
  @skip(if: $isAnyResourceMissing)
{
  createPost(input: {
    status: draft,
    slug: $postSlug
    title: $postTitle
    contentAs: {
      html: $postContent
    },
    excerpt: $postExcerpt
    authorBy: {
      username: $postAuthorUsername
    },
    featuredImageBy: $featuredImageMutationInput,
    categoriesBy: {
      slugs: $postCategorySlugs
    },
    tagsBy: {
      slugs: $postTagSlugs
    }
  }) {
    status
    errors {
      __typename
      ...on ErrorPayload {
        message
      }
    }
    post {
      id
      date
      status
 
      slug
      title
      content
      excerpt
 
      author {
        id
        username
      }
      featuredImage {
        id
        slug
      }
      categories {
        id
        slug
      }
      tags {
        id
        slug
      }
    }
  }
}

(Como hemos visto en lecciones anteriores del tutorial) Usamos la funcionalidad Field to Input (con la sintaxis $__field) para pasar el valor resuelto del campo a un campo contiguo.

Cuando necesitamos pasar el valor resuelto del campo a una directiva, debemos en cambio usar la directiva @passOnwards (que también es proporcionada por la extensión Field To Input).

Esta consulta:

{
  posts {
    id
    hasComments
    notHasComments: _not(value: $__hasComments)
  }
}

...es equivalente a esta consulta:

{
  posts {
    id
    hasComments
    notHasComments: hasComments
      @passOnwards(as: "postHasComments")
      @applyField(
        name: "_not"
        arguments: {
          value: $postHasComments
        },
        setResultInResponse: true
      )
  }
}

@passOnwards es útil para producir algún cálculo sobre el valor del campo. Por ejemplo, en la consulta GraphQL de arriba, se usa para comprobar si la propiedad user no es null, antes de extraer su propiedad username (y sobrescribir el valor del campo con ella):

  postAuthorUsername: _objectProperty(
    object: $__postData,
    by: { key: "author" }
  )
    @passOnwards(
      as: "author"
    )
    @applyField(
      name: "_notNull",
      arguments: {
        value: $author
      },
      passOnwardsAs: "hasAuthor"
    )
    @if(condition: $hasAuthor)
      @applyField(
        name: "_objectProperty",
        arguments: {
          object: $author,
          by: { key: "username" }
        },
        setResultInResponse: true
      )
    @export(as: "postAuthorUsername")
    @remove

[WIP] Importando automáticamente recursos faltantes

El esquema de Gato GraphQL debe ser ampliado con mutaciones para:

  • Crear/actualizar usuarios (#2456)
  • Crear/actualizar categorías (#2457)

Esto es un trabajo en progreso. Una vez que estas mutaciones sean soportadas, podremos hacer que la consulta GraphQL importe automáticamente cada uno de los recursos faltantes.