使用fxml从Erlang提取数据：ejabberd 16.04转义字符问题求助

Hey there! I get it—you need to keep raw Unicode escape sequences like g\u000ag intact instead of having them converted to actual line breaks (g\ng) when pulling data from Erlang via fxml in ejabberd 16.04. Let’s walk through some practical solutions to fix this:

1. Use a Custom Post-Processing Function to Re-Escape Characters #

Since ejabberd’s fxml module in 16.04 automatically resolves \uXXXX escape sequences to their corresponding characters, the quickest fix is to reverse this conversion after parsing. Write a simple Erlang function that scans the output string and converts control characters back to their Unicode escape format:

revert_unicode_escapes(InputStr) ->
    lists:flatmap(fun(Char) ->
        case Char of
            $\n -> "\\u000a";  % Target newline specifically
            $\t -> "\\u0009";  % Add other control characters if needed
            $\r -> "\\u000d";
            C when C < 32 -> io_lib:format("\\u~4.16.0b", [C]);
            _ -> [Char]
        end
    end, InputStr).

Just pass your parsed fxml string through this function, and it’ll turn any line breaks back into \u000a, preserving the original escape syntax you need.

2. Modify ejabberd’s FXML Parsing Logic (Advanced) #

If you want to stop the escape resolution at the source, you’ll need to tweak ejabberd’s fxml.erl module:

• Locate the section of code that handles Unicode escape sequences (look for functions parsing \u followed by hex digits).
• Comment out or disable that parsing block so the raw \uXXXX string is retained instead of being converted to a character.
• Recompile ejabberd with your modified code and restart the service.

⚠️ Heads up: This requires familiarity with Erlang and ejabberd’s codebase, and it might break other functionality if done incorrectly. Test thoroughly in a staging environment first!

3. Verify the Data Flow #

Double-check that no other components in your pipeline are modifying the string. Add debug logs at key points (right after extracting from Erlang, before fxml parsing, after parsing) to pinpoint exactly where the escape sequence gets converted. Sometimes hooks or XMPP routing modules might be altering the data without you noticing.

Pick the solution that fits your technical comfort level—most folks start with the post-processing function since it’s low-risk and easy to implement.

内容的提问来源于stack exchange，提问作者Pawan