Schema-tutorial
Schema-tutorialLes 29: Een bericht importeren van een andere WordPress-site

Les 29: Een bericht importeren van een andere WordPress-site

Deze tutorial-les laat zien hoe je WordPress-sites gesynchroniseerd kunt houden door een bericht van een WordPress-site te importeren naar je lokale WordPress-site.

GraphQL-query om een bericht te importeren van een andere WordPress-site

De onderstaande GraphQL-query verbindt zich met het GraphQL-eindpunt van een upstream-website, haalt de gegevens op van een specifiek bericht en importeert het lokaal. De Gato GraphQL-plugin (gratis versie) moet ook op de upstream-website geïnstalleerd zijn.

(Als Gato GraphQL niet geïnstalleerd is op de upstream-site, kan de query aangepast worden om verbinding te maken met de WP REST API-eindpunten ervan.)

Alle bronnen waarnaar in het bericht verwezen wordt, moeten lokaal bestaan:

  • De auteur
  • De uitgelichte afbeelding (indien aanwezig)
  • De categorieën
  • (Tags ook, maar als deze nog niet bestaan, worden ze samen met het bericht aangemaakt, dus dat is geen probleem)

Als gemeenschappelijke identificator voor bronnen tussen de upstream- en lokale sites gebruiken we:

  • Slugs voor categorieën, tags en media-items
  • Gebruikersnamen voor gebruikers

Als een van de bronnen niet bestaat op de lokale site, geeft de GraphQL-query een fout en stopt het importeren.

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
      }
    }
  }
}

(Zoals we in eerdere tutorial-lessen hebben gezien) We gebruiken de Field to Input-functie (met de syntaxis $__field) om de opgeloste waarde van een veld door te geven aan een aangrenzend veld.

Als we de opgeloste waarde van een veld aan een directive moeten doorgeven, moeten we in plaats daarvan de directive @passOnwards gebruiken (die eveneens geleverd wordt door de Field to Input-extensie).

Deze query:

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

...is equivalent aan deze query:

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

@passOnwards is handig om een berekening uit te voeren op de waarde van een veld. In de bovenstaande GraphQL-query wordt het bijvoorbeeld gebruikt om te controleren of de eigenschap user niet null is, voordat de eigenschap username eruit wordt gehaald (en de veldwaarde ermee wordt overschreven):

  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] Automatisch ontbrekende bronnen importeren

Het Gato GraphQL-schema moet uitgebreid worden met mutaties om:

  • Gebruikers aan te maken/bij te werken (#2456)
  • Categorieën aan te maken/bij te werken (#2457)

Dit is werk in uitvoering. Zodra deze mutaties ondersteund worden, kan de GraphQL-query elk van de ontbrekende bronnen automatisch importeren.