如何使用 R 或 python 从 postgres bytea 列下载图像？

Question

基本上，我有一个名为“person”的表的本地 postgres 数据库，它有一个名为“image”的列，这是一个包含 .png 图像的 bytea 列。我不使用 postgresql，我想将图像下载为来自另一列的名称，后缀为“.png”

我found 的所有答案都是 postgres 方面的答案，我真的无法接受。 R或python中是否有可以下载图像的正版包？

Answer 1

这是使用R的解决方案：

# Packages we need
require("RPostgreSQL")
require('jsonlite')

# Create connection to database
pgConn <- dbConnect(PostgreSQL(), dbname="your_db", host='127.0.0.1')

# Query string - edit this to suit your needs
# Important thing here is that we're getting Postgres to base64 encode
#   the image data (converting it from binary to text)
thisQ = "SELECT encode(imageColumn, 'base64') AS image from test_table WHERE name='image';"

# Execute the SELECT query and fetch the results
resultSet = dbSendQuery(pgConn, thisQ)
resultData <- fetch(resultSet, n=-1)
dbClearResult(resultSet)

# Get the image data as text
imageData <- resultData$image

# Decode from base64 back to binary
imageDataDecoded <- jsonlite::base64_dec(imageData)

# Create a file connection and write the binary data to disk using mode "wb".
write.filename = file("/temp/file.png", "wb")
writeBin(imageDataDecoded, write.filename)
close(write.filename)