JSON Parser

Parses JSON strings into structures and cells

Description

This function parses JSON strings. It converts JSON arrays into cell arrays and JSON objects into structures.

This can be used with webervices that return JSON data such as the API provided by Google®.

An example of use is:
  google_search = 'http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=matlab';
  matlab_results = parse_json(urlread(google_search));
  disp(matlab_results{1}.responseData.results{1}.titleNoFormatting)
  disp(matlab_results{1}.responseData.results{1}.visibleUrl)

• Acknowledgements: This submission has inspired the following:; (another) JSON Parser , Highly portable JSON-input parser
• MATLAB release: MATLAB 7.5 (R2007b)
• Other Files: license.txt, ; parse_json.m

[port tracker]

Good work!
BTW - Any reason why it only return 4 value object from google? Is it because of the ajax api?

Thanks,

port

[Joel Feenstra]

The Google API limits it to 4 results. You can use the "cursor" information to fetch more results: matlab_results{1}.responseData.cursor

[Patrick Boert]

Hallo Joel,

thanks for the work!

I'm trying to query the Chruchbase API and it seems to work fine. However, it takes ages for some queries to get parsed, e.g. I quit

companies=parse_json(urlread('http://api.crunchbase.com/v/1/companies.js'));

after 1 hour. The profiler says that

json(1) = []; in parse_json>parse_string
json(1) = []; in parse_json>parse_object

make up about 90 % of the computational cost. Is there some easy way around this?

Best,
Patrick

[François Glineur]

An alternative parser with faster handling of strings is available at http://www.mathworks.com/matlabcentral/fileexchange/23393
(another JSON Parser). For example, running the example above

companies=parse_json(urlread('http://api.crunchbase.com/v/1/companies.js'));

with it now takes less than 30 seconds.

[Joel Feenstra]

I know that the code is slow, and I made no attempt to make the code fast, just correct. François's version does seem to be faster, so if you need speed (and have a lot of strings), use his.

[Patrick Boert]

Thanks Joel, I thought maybe there would be an easy workaround you could point me to. But the new file solves the issue, it is faster by some magnitude. In any case, thanks for your work.