Generate an optimized post's featured image using Stable Diffusion and TinyPNG

This Persisted GraphQL query uses Stable Diffusion generative AI to produce images for posts without a featured image.

It first checks if a post has a featured image. If it does not, it creates one by calling Stable Diffusion's generative AI service. We must provide the API key to use it.

As the generative AI images are not optimized for the web, the query can also send the newly-generated image to TinyPNG to compress it. We must provide the API key to use it.

Finally, the query creates a new media item with the image, and sets it as the post's featured image.

query InitializeVariables(
  $tinyPngAPIKey: String
)
  @configureWarningsOnExportingDuplicateVariable(enabled: false)
{
  isFeaturedImageMissing: _echo(value: false)
    @export(as: "isFeaturedImageMissing")
    @remove
 
  isPostTitleNotEmpty: _echo(value: false)
    @export(as: "isPostTitleNotEmpty")
    @remove
 
  generatedImageURL: _echo(value: null)
    @export(as: "generatedImageURL")
    @remove
 
  isImageGenerated: _echo(value: false)
    @export(as: "isImageGenerated")
    @remove
 
  mimeType: _echo(value: null)
    @export(as: "mimeType")
    @remove
 
  isMediaItemCreated: _echo(value: false)
    @export(as: "isMediaItemCreated")
    @remove
 
  useTinyPng: _notEmpty(value: $tinyPngAPIKey)
    @export(as: "useTinyPng")
    @remove
}
 
query ExportPostData(
  $postID: ID!
)
  @depends(on: "InitializeVariables")
{
  post(by: { id: $postID }, status: any) {
    hasFeaturedImage
    isFeaturedImageMissing: hasFeaturedImage
      @boolOpposite
      @export(as: "isFeaturedImageMissing")
    title
      @export(as: "postTitle")
    rawTitle
      @remove
    isPostTitleNotEmpty: _notEmpty(value: $__rawTitle)
      @export(as: "isPostTitleNotEmpty")
    mediaItemFilename: rawTitle
      @default(value: "untitled", condition: IS_EMPTY)
      @strLowerCase
      @strSubstr(offset: 0, length: 20)
      @export(as: "filename")
      @remove
  }
}
 
query GenerateImageUsingStableDiffusion(
  $stableDiffusionAPIKey: String!
  $width: Int! = 1024
  $height: Int! = 1024
)
  @depends(on: "ExportPostData")
  @include(if: $isFeaturedImageMissing)
  @include(if: $isPostTitleNotEmpty)
{
  stableDiffusionResponse: _sendJSONObjectItemHTTPRequest(input: {
    url: "https://stablediffusionapi.com/api/v3/text2img",
    method: POST,
    options: {
      json: {
        key: $stableDiffusionAPIKey
        prompt: $postTitle,
        width: $width
        height: $height
        samples: 1
      }
    }
  })
    @underJSONObjectProperty(by: { key: "output" })
      @underArrayItem(index: 0)
        @export(as: "generatedImageURL")
  
  stableDiffusionImageCaption: _sprintf(
    string: "Image created by Stable Diffusion using prompt: '%s'",
    values: [$postTitle]
  )
    @export(as: "imageCaption")
  
  stableDiffusionMediaItemFilename: _sprintf(
    string: "%s.png",
    values: [$filename]
  )
    @export(as: "filename")
}
 
query CheckIsImageGenerated
  @depends(on: "GenerateImageUsingStableDiffusion")
  @include(if: $isFeaturedImageMissing)
  @include(if: $isPostTitleNotEmpty)
{
  isImageGenerated: _notEmpty(value: $generatedImageURL)
    @export(as: "isImageGenerated")
}
 
query MaybeCompressGeneratedImage(
  $tinyPngAPIKey: String
)
  @depends(on: "CheckIsImageGenerated")
  @include(if: $isImageGenerated)
  @include(if: $useTinyPng)
{
  compressedImageResponse: _sendHTTPRequest(input: {
    url: "https://api.tinify.com/shrink",
    method: POST,
    options: {
      auth: {
        password: $tinyPngAPIKey
      },
      headers: [
        {
          name: "Content-Type",
          value: "application/json"
        }
      ],
      json: {
        source: {
          url: $generatedImageURL
        }
      }
    }
  }) {
    body
      @remove
    bodyJSONObject: _strDecodeJSONObject(string: $__body)
 
    mimeType: _objectProperty(
      object: $__bodyJSONObject
      by: { path: "output.type" }
    )
      @export(as: "mimeType")
 
    generatedImageURL: header(name: "Location")
      @export(as: "generatedImageURL")
  }
}
 
mutation CreateMediaItemFromGeneratedImage
  @depends(on: "MaybeCompressGeneratedImage")
  @include(if: $isImageGenerated)
{
  createMediaItem(input: {
    from: {
      url: {
        source: $generatedImageURL
        filename: $filename
      }
    }
    title: $postTitle
    caption: $imageCaption
    altText: $postTitle
    mimeType: $mimeType
  }) {
    mediaItemID
      @export(as: "mediaItemID")
    isMediaItemCreated: _notNull(value: $__mediaItemID)
      @export(as: "isMediaItemCreated")
      @remove
 
    status
    errors {
      __typename
      ...on ErrorPayload {
        message
      }
    }
    mediaItem {
      altText
      caption
      mimeType
      slug
      src
      title
    }
  }
}
 
mutation GenerateOptimizedPostFeaturedImageUsingStableDiffusion(
  $postID: ID!
)
  @depends(on: "CreateMediaItemFromGeneratedImage")
  @include(if: $isMediaItemCreated)
{
  setFeaturedImageOnCustomPost(input: {
    customPostID: $postID
    mediaItemBy: { id: $mediaItemID }
  }) {
    status
    errors {
      __typename
      ...on ErrorPayload {
        message
      }
    }
    customPost {
      __typename
      ...on CustomPost {
        featuredImage {
          id
          altText
          caption
          mimeType
          slug
          src
          title
        }
      }
    }
  }
}