C# quoted string within a quoted string

Question

I'm trying to run JQ on a JSON file, through command line from C# code. One of the required arguments includes spaces and quotation marks, so it is itself wrapped between quotation mark. However, this argument is formatted from another string which includes quotations marks:

var jq =  ".data[] | select(.name==\"mytest\") | .id == \"adxd\"";
var psi = new ProcessStartInfo
        {
            FileName = _exe,
            Arguments = $"-c \"{jq}\" {_settings.JSONFile}",
        };

However, the arguments turn out as:

-c ".data[] | select(.name=="mytest") | .id == "adxd"" json.json

Which of course is wrong. It should turn out as:

-c ".data[] | select(.name==\"mytest\") | .id == \"adxd\"" json.json

How can I ensure that the the arguments are decoded correctly with the correct 'levels' of quotation marks?

[This](https://stackoverflow.com/questions/14339701/c-sharp-process-start-needs-arguments-with-double-quotes-they-disappear) should help but I'm trying to find something better. — gunr2171, Jan 26 '22 at 13:39
I'm open for other suggestions @Llama! My modest research brought me to https://stedolan.github.io/jq/ — Ahmad Masalha, Jan 26 '22 at 13:56
It does not support the functionality I need. I need to be able to run user-provided queries on some json. With JSON.NET the user would have to write actual code as input, rather than simple commands such as in the link I provided. (Unless I missed something) — Ahmad Masalha, Jan 26 '22 at 14:04

score 2 · Accepted Answer · answered Jan 26 '22 at 13:53

Ask yourself: "why are there quotes around the query argument?"

That's because you're adding an escaped quote. The idea here is that writing \" in the "code" renders " in the output.

You're issue is that you need to do this one layer down. You don't want to render the quotes inside the query in C#, you want to render the quotes in the jq.exe application. So you need to work backwards.

Inside jp.exe, the value should be ".
This means that whatever we send to it (the command line arguments) need to be escaped: \".
This means that however we render the command line arguments will need to produce \", and because both of those characters require escaping, you do it.

jq = jq.Replace("\"", "\\\"");

This says "replace all double quotes in my c# string with a backslash and quote" (essentially, just add a backslash before all quotes).

This turns a c# string rendered as abc "def" ghi into abc \"def\" ghi, which is the format your command line argument is expecting.

C# quoted string within a quoted string

1 Answers1