Json regex deserialization with JSON.Net - regex

Question

I'm trying to read the following example json from a text file into a string using the JSON.Net parsing library.
Content of C:\temp\regeLib.json
{
"Regular Expressions Library":
{
"SampleRegex":"^(?<FIELD1>\d+)_(?<FIELD2>\d+)_(?<FIELD3>[\w\&-]+)_(?<FIELD4>\w+).txt$"
}
}
Example code to try and parse:
Newtonsoft.Json.Converters.RegexConverter rConv = new Newtonsoft.Json.Converters.RegexConverter();
using (StreamReader reader = File.OpenText(libPath))
{
string foo = reader.ReadToEnd();
JObject jo = JObject.Parse(foo);//<--ERROR
//How to use RegexConverter to parse??
Newtonsoft.Json.JsonTextReader jtr = new Newtonsoft.Json.JsonTextReader(reader);
JObject test = rConv.ReadJson(jtr);//<--Not sure what parameters to provide
string sampleRegex = test.ToString();
}
It seems I need to use the converter, I know the code above is wrong, but I can't find any examples that describe how / if this can be done. Is it possible to read a regular expression token from a text file to a string using JSON.Net? Any help is appreciated.
UPDATE:
Played with it more and figured out I had to escape the character classes, once I made the correction below I was able to parse to a JObject and use LINQ to query for the regex pattern.
Corrected content C:\temp\regeLib.json
{
"Regular Expressions Library":
{
"SampleRegex":"^(?<FIELD1>\\d+)_(?<FIELD2>\\d+)_(?<FIELD3>[\\w\\&-]+)_(?<FIELD4>\\w+).txt$"
}
}
Corrected code
using (StreamReader reader = File.OpenText(libPath))
{
string content = reader.ReadToEnd().Trim();
JObject regexLib = JObject.Parse(content);
string sampleRegex = regexLib["Regular Expressions Library"]["SampleRegex"].ToString();
//Which then lets me do the following...
Regex rSampleRegex = new Regex(sampleRegex);
foreach (string sampleFilePath in Directory.GetFiles(dirSampleFiles, "*"))
{
filename = Path.GetFileName(sampleFilePath);
if (rSampleRegex.IsMatch(filename))
{
//Do stuff...
}
}
}
Not sure if this is the best approach, but it seems to work for my case.

Answer 1

i don't understand why you have to store such a small regex in a json file, are you going to expand the regex in the future?
if so, rather than doing this
JObject regexLib = JObject.Parse(content);
string sampleRegex = regexLib["Regular Expressions Library"]["SampleRegex"].ToString();
Consider using json2csharp to make classes, at least it's strongly-typed and make it more maintainable.
I think a more appropriate json would look like this (assumptions):
{
"Regular Expressions Library": [
{
"SampleRegex": "^(?<FIELD1>\\d+)_(?<FIELD2>\\d+)_(?<FIELD3>[\\w\\&-]+)_(?<FIELD4>\\w+).txt$"
},
{
"SampleRegex2": "^(?<FIELD1>\\d+)_(?<FIELD2>\\d+)_(?<FIELD3>[\\w\\&-]+)_(?<FIELD4>\\w+).txt$"
}
]
}
It would make more sense this way to store a regex in a "settings" file