require "google/cloud/vision"

An error occurred and I got stuck. (I ate a lot of time because of this)

2, authentication settings

In order to use the Google Cloud Vision API, you need to create a dedicated json file and load it into the target rails app. ・ Create json file ▶ ︎ Do not get stuck with the procedure according to the document. The completed file looks like this

{
  "type": "",
  "project_id": "",
  "private_key_id": "private_key_Contents of id",
  "private_key": "-----BEGIN PRIVATE KEY-----Contents\=\n-----END PRIVATE KEY-----\n",
  "client_email": "",
  "client_id": "",
  "auth_uri": "",
  "token_uri": "",
  "auth_provider_x509_cert_url": "",
  "client_x509_cert_url": ""
}

・ Load into rails app ▶ ︎.Enter in bash_profile and pass the path

export GOOGLE_APPLICATION_CREDENTIALS="$PATH:Write the path/file name.json"

3, actually use it.

routes.rb

get  "contents/index"  => "contents#index"

contents_controller.rb

class ContentsController < ApplicationController
  def index
  end
end

index.erb

<%=
#Load the gem you just installed
require "google/cloud/vision"

#Instantiation
image_annotator = Google::Cloud::Vision.image_annotator

#Enter the image path (local or online image is fine)
file_name = "./resources/cat.jpg "

#Return value returned after recognizing the image
response = image_annotator.label_detection image: file_name
response.responses.each do |res|
  puts "Labels:"
  res.label_annotations.each do |label|
    puts label.description
  end
end
%>

4, contents / index When redialing ...

If you see a return value like this, you're successful! (Since I captured the image of a cat as a trial, "Cat" appears. Lol)

From here, you can get the information you want and format it so that you can use it for good! Thank you for reading !!