postgresql - Postgres row_to_json produces invalid JSON with double escaped quotes -

postgres escapes quotes incorrectly when creating json export. note double quotes in below update...

update models set column='"hello"' id=1;  copy (select row_to_json(models)     (select column shaders id=1) shaders)     '/output.json'; 

the contents of output.json:

{"column":"\\"hello\\""} 

you can see quotes escaped improperly , creates invalid json. should be:

{"column":"\"hello\""} 

how can fix postgres bug or work around it?

this not json related. it's way text format (default) in copy command handles backslashes. the postgresql documentation - copy:

backslash characters (\) can used in copy data quote data characters might otherwise taken row or column delimiters. in particular, following characters must preceded backslash if appear part of column value: backslash itself, newline, carriage return, , current delimiter character.

(emphasis mine.)
can solve using csv-format , changing quote character doublequote else.

to demonstrate:

select row_to_json(row('"hello"'))  | "{"f1":"\"hello\""}" | 

copy (select row_to_json(row('"hello"'))) '/output.json';  | {"f1":"\\"hello\\""} | 

copy (select row_to_json(row('"hello"'))) '/output.json' csv quote '$';  | {"f1":"\"hello\""} |