regular expression to extract JSON string from text

Question

I'm looking for regex to extract json string from text. I have the text below, which contains

JSON string(mTitle, mPoster, mYear, mDate)

like that:

{"999999999":"138138138","020202020202":{"846":{"mTitle":"\u0430","mPoster":{"
small":"\/upload\/ms\/b_248.jpg","middle":"600.jpg","big":"400.jpg"},"mYear"
:"2013","mDate":"2014-01-01"},"847":{"mTitle":"\u043a","mPoster":"small":"\/upload\/ms\/241.jpg","middle":"600.jpg","big":"
138.jpg"},"mYear":"2013","mDate":"2013-12-26"},"848":{"mTitle":"\u041f","mPoster":{"small":"\/upload\/movies\/2
40.jpg","middle":"138.jpg","big":"131.jpg"},"mYear":"2013","mDate":"2013-12-19"}}}

In order to parse JSON string I should extract JSON string from the text. That is why, my question: Could you help me to get only JSON string from text? Please help.

I've tried this regular expression with no success:

{"mTitle":(\w|\W)*"mDate":(\w|\W)*}

Solution

The following regex should work:

\{\s*"mTitle"\s*:\s*(.+?)\s*,\s*"mPoster":\s*(.+?)\s*,\s*"mYear"\s*:\s*(.+?)\s*,\s*"mDate"\s*:\s*(.+?)\s*\}

Check demo here.

The main difference from your regex is the .+? part, that, broken down, means:

• Match any character (.)
• One or more times (+)
• As little as possible (?)

The ? operator after the + is very important here --- because if you removed it, the first .+ (in \{\s*"mTitle"\s*:\s*(.+?)) would match the whole text, not the text up to the "mPoster" word, that is what you want.

Notice it is just a more complicated version of \{"mTitle":(.+?),"mPoster":(.+?),"mYear":(.+?),"mDate":(.+?)\} (with \s* to match spaces, allowed by the JSON notation).