v1 Receive messages of Avro schema type (DEPRECATED)

  import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "os" 
  
 "sync" 
  
 "time" 
  
 "cloud.google.com/go/pubsub" 
  
 "github.com/linkedin/goavro/v2" 
 ) 
 func 
  
 subscribeWithAvroSchema 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 projectID 
 , 
  
 subID 
 , 
  
 avscFile 
  
 string 
 ) 
  
 error 
  
 { 
  
 // projectID := "my-project-id" 
  
 // topicID := "my-topic" 
  
 // avscFile = "path/to/an/avro/schema/file(.avsc)/formatted/in/json" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 pubsub 
 . 
  NewClient 
 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "pubsub.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 avroSchema 
 , 
  
 err 
  
 := 
  
 os 
 . 
 ReadFile 
 ( 
 avscFile 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "os.ReadFile err: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 codec 
 , 
  
 err 
  
 := 
  
 goavro 
 . 
 NewCodec 
 ( 
 string 
 ( 
 avroSchema 
 )) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "goavro.NewCodec err: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 sub 
  
 := 
  
 client 
 . 
 Subscription 
 ( 
 subID 
 ) 
  
 ctx2 
 , 
  
 cancel 
  
 := 
  
 context 
 . 
 WithTimeout 
 ( 
 ctx 
 , 
  
 10 
 * 
 time 
 . 
 Second 
 ) 
  
 defer 
  
 cancel 
 () 
  
 var 
  
 mu 
  
 sync 
 . 
 Mutex 
  
 sub 
 . 
 Receive 
 ( 
 ctx2 
 , 
  
 func 
 ( 
 ctx 
  
 context 
 . 
 Context 
 , 
  
 msg 
  
 * 
 pubsub 
 . 
 Message 
 ) 
  
 { 
  
 mu 
 . 
 Lock 
 () 
  
 defer 
  
 mu 
 . 
 Unlock 
 () 
  
 encoding 
  
 := 
  
 msg 
 . 
 Attributes 
 [ 
 "googclient_schemaencoding" 
 ] 
  
 var 
  
 state 
  
 map 
 [ 
 string 
 ] 
 interface 
 {} 
  
 if 
  
 encoding 
  
 == 
  
 "BINARY" 
  
 { 
  
 data 
 , 
  
 _ 
 , 
  
 err 
  
 := 
  
 codec 
 . 
 NativeFromBinary 
 ( 
 msg 
 . 
 Data 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "codec.NativeFromBinary err: %v\n" 
 , 
  
 err 
 ) 
  
 msg 
 . 
 Nack 
 () 
  
 return 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Received a binary-encoded message:\n%#v\n" 
 , 
  
 data 
 ) 
  
 state 
  
 = 
  
 data 
 .( 
 map 
 [ 
 string 
 ] 
 interface 
 {}) 
  
 } 
  
 else 
  
 if 
  
 encoding 
  
 == 
  
 "JSON" 
  
 { 
  
 data 
 , 
  
 _ 
 , 
  
 err 
  
 := 
  
 codec 
 . 
 NativeFromTextual 
 ( 
 msg 
 . 
 Data 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "codec.NativeFromTextual err: %v\n" 
 , 
  
 err 
 ) 
  
 msg 
 . 
 Nack 
 () 
  
 return 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Received a JSON-encoded message:\n%#v\n" 
 , 
  
 data 
 ) 
  
 state 
  
 = 
  
 data 
 .( 
 map 
 [ 
 string 
 ] 
 interface 
 {}) 
  
 } 
  
 else 
  
 { 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Unknown message type(%s), nacking\n" 
 , 
  
 encoding 
 ) 
  
 msg 
 . 
 Nack 
 () 
  
 return 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "%s is abbreviated as %s\n" 
 , 
  
 state 
 [ 
 "name" 
 ], 
  
 state 
 [ 
 "post_abbr" 
 ]) 
  
 msg 
 . 
 Ack 
 () 
  
 }) 
  
 return 
  
 nil 
 } 
 

  # subscription_id = "your-subscription-id" 
 # avsc_file = "path/to/an/avro/schema/file/(.avsc)/formatted/in/json" 
 pubsub 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  Pubsub 
 
 . 
 new 
 subscription 
  
 = 
  
 pubsub 
 . 
 subscription 
  
 subscription_id 
 subscriber 
  
 = 
  
 subscription 
 . 
 listen 
  
 do 
  
 | 
 received_message 
 | 
  
 encoding 
  
 = 
  
 received_message 
 . 
 attributes 
 [ 
 "googclient_schemaencoding" 
 ] 
  
 case 
  
 encoding 
  
 when 
  
 "BINARY" 
  
 require 
  
 "avro" 
  
 avro_schema 
  
 = 
  
 Avro 
 :: 
 Schema 
 . 
 parse 
  
 File 
 . 
 read 
 ( 
 avsc_file 
 ) 
  
 buffer 
  
 = 
  
 StringIO 
 . 
 new 
  
 received_message 
 . 
 data 
  
 decoder 
  
 = 
  
 Avro 
 :: 
 IO 
 :: 
 BinaryDecoder 
 . 
 new 
  
 buffer 
  
 reader 
  
 = 
  
 Avro 
 :: 
 IO 
 :: 
 DatumReader 
 . 
 new 
  
 avro_schema 
  
 message_data 
  
 = 
  
 reader 
 . 
 read 
  
 decoder 
  
 puts 
  
 "Received a binary-encoded message: 
 \n 
 #{ 
 message_data 
 } 
 " 
  
 when 
  
 "JSON" 
  
 require 
  
 "json" 
  
 message_data 
  
 = 
  
 JSON 
 . 
 parse 
  
 received_message 
 . 
 data 
  
 puts 
  
 "Received a JSON-encoded message: 
 \n 
 #{ 
 message_data 
 } 
 " 
  
 else 
  
 "Received a message with no encoding: 
 \n 
 #{ 
 received_message 
 . 
 message_id 
 } 
 " 
  
 end 
  
 received_message 
 . 
 acknowledge! 
 end 
 subscriber 
 . 
 start 
 # Let the main thread sleep for 60 seconds so the thread for listening 
 # messages does not quit 
 sleep 
  
 60 
 subscriber 
 . 
 stop 
 . 
 wait!