Tutoriel du schéma
Tutoriel du schémaLeçon 29 : Importer un article depuis un autre site WordPress

Leçon 29 : Importer un article depuis un autre site WordPress

Cette leçon du tutoriel montre comment nous pouvons maintenir des sites WordPress synchronisés, en important un article depuis un site WordPress vers notre site WordPress local.

Requête GraphQL pour importer un article depuis un autre site WordPress

La requête GraphQL ci-dessous se connecte au point de terminaison GraphQL d'un site web en amont, récupère les données d'un article spécifique, et l'importe localement. Le plugin Gato GraphQL (version gratuite) doit également être installé sur le site web en amont.

(Si Gato GraphQL n'est pas installé sur le site en amont, la requête peut être adaptée pour se connecter à ses points de terminaison de l'API REST WP à la place.)

Les ressources référencées dans l'article doivent toutes exister localement :

  • L'auteur
  • L'image mise en avant (le cas échéant)
  • Les catégories
  • (Les étiquettes aussi, cependant si celles-ci n'existent pas encore, elles sont créées en même temps que l'article, donc ce n'est pas un problème)

Comme identifiant commun pour les ressources entre les sites en amont et local, nous utilisons :

  • Les slugs pour les catégories, étiquettes et éléments médias
  • Les noms d'utilisateur pour les utilisateurs

Si l'une des ressources n'existe pas sur le site local, la requête GraphQL affiche une erreur et interrompt l'importation.

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
      }
    }
  }
}

(Comme nous l'avons vu dans les leçons précédentes du tutoriel) Nous utilisons la fonctionnalité Field to Input (avec la syntaxe $__field) pour passer la valeur résolue du champ à un champ contigu.

Lorsque nous avons besoin de passer la valeur résolue du champ à une directive, nous devons à la place utiliser la directive @passOnwards (qui est également fournie par l'extension Field to Input).

Cette requête :

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

...est équivalente à cette requête :

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

@passOnwards est utile pour produire un calcul sur la valeur du champ. Par exemple, dans la requête GraphQL ci-dessus, elle est utilisée pour vérifier si la propriété user n'est pas null, avant d'extraire sa propriété username (et de remplacer la valeur du champ par celle-ci) :

  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] Importation automatique des ressources manquantes

Le schéma de Gato GraphQL doit être étendu avec des mutations pour :

  • Créer/mettre à jour des utilisateurs (#2456)
  • Créer/mettre à jour des catégories (#2457)

C'est un travail en cours. Une fois ces mutations prises en charge, nous pourrons faire en sorte que la requête GraphQL importe automatiquement chacune des ressources manquantes.