Package: graze
grazeCache (a tiny part of) the internet.(For the technically inclined, graze is meant to enable the separation of the concerns
of getting and caching data from the internet.)installpip install grazeExamplefromgrazeimportGrazeimportosrootdir=os.path.expanduser('~/graze')g=Graze(rootdir)list(g)If this is your first time, you got nothing:[]So get something. For no particular reason let's be self-referential and get myself:url='https://raw.githubusercontent.com/thorwhalen/graze/master/README.md'content=g[url]type(content),len(content)Before I grew up, I had only 46 petty bytes:(bytes, 46)These were:print(content.decode())# graze

Cache (a tiny part of) the internetBut now, here's the deal. List yourgkeys now. Go ahead, don't be shy!list(g)['https://raw.githubusercontent.com/thorwhalen/graze/master/README.md']What does that mean?I means you have a local copy of these contents.The file path isn't reallyhttps://..., it'srootdir/https/..., but you
only have to care about that if you actually have to go get the file with
something else than graze. Because graze will give it to you.How? Same way you got it in the first place:content_2 = g[url]
assert content_2 == contentBut this time, it didn't ask the internet. It just got it's local copy.And if you want a fresh copy?No problem, just delete your local one. You guessed!
The same way you would delete a key from a dict:delg[url]Q&AThe pages I need to slurp need to be rendered, can I use selenium of other such engines?Sure!We understand that sometimes you might have special slurping needs -- such
as needing to let the JS render the page fully, and/or extract something
specific, in a specific way, from the page.Selenium is a popular choice for these needs.grazedoesn't install selenium for you, but if you've done that, you just
need to specify a differentInternetobject forGrazeto source from,
and to make an internet object, you just need to specify what aurl_to_contentsfunction that does exactly what it says.Note that the contents need to be returned in bytes forGrazeto work.If you want to use some of the defaultseleniumurl_to_contentsfunctions
to make anInternet(we got Chrome, Firefox, Safari, and Opera),
you go ahead! here's an example using the default Chrome driver
(again, you need to have the driver installed already for this to work;
seehttps://selenium-python.readthedocs.io/):fromgrazeimportGraze,url_to_contents,Internetg=Graze(source=Internet(url_to_contents=url_to_contents.selenium_chrome))And if you'll be using it often, just do:fromgrazeimportGraze,url_to_contents,Internetfromfunctoolsimportpartialmy_graze=partial(Graze,rootdir='a_specific_root_dir_for_your_project',source=Internet(url_to_contents=url_to_contents.selenium_chrome))# and then you can just dog=my_graze()# and get on with the fun...What if I want a fresh copy of the data?Classic caching problem.
You like the convenience of having a local copy, but then how do you keep in sync with the data source if it changes?If you KNOW the source data changed and want to sync, it's easy. You delete the local copy
(like deleting a key from a dict:del Graze()[url])
and you try to access it again.
Since you don't have a local copy, it will get one from theurlsource.What if you want this to happen automatically?Well, there's several ways to do that.If you have a way to know if the source and local are different (through modified dates, or hashes, etc.),
then you can write a little function to keep things in sync.
But that's context dependent;grazedoesn't offer you any default way to do it.Another way to do this is sometimes known as aTTL Cache(time-to-live cache).
You get such functionality with thegraze.GrazeWithDataRefreshstore, or for most cases,
simply getting your data through thegrazefunction
specifying amax_agevalue (in seconds):from graze import graze

content_bytes = graze(url, max_age=in_seconds)Can I make graze notify me when it gets a new copy of the data?Sure! Just specify akey_ingressfunction when you make yourGrazeobject, or
callgraze. This function will be called on the key (the url) just before contents
are being downloaded from the internet. The typical function would be:key_ingress=lambdakey:print(f"Getting{key}from the internet")Does graze work for dropbox links?Yes it does, but you need to be aware that dropbox systematically send the data as a zip,even if there's only one file in it.Here's some code that can help.defzip_store_of_gropbox_url(dropbox_url:str):"""Get a key-value perspective of the (folder) contentsof the zip a dropbox url gets you"""fromgrazeimportgrazefrompy2storeimportFilesOfZipreturnFilesOfZip(graze(dropbox_url))deffilebytes_of_dropbox_url(dropbox_url:str,assert_only_one_file=True):"""Get the bytes of the first file in a zip that a dropbox url gives you"""zip_store=zip_store_of_gropbox_url(dropbox_url)zip_filepaths=iter(zip_store)first_filepath=next(zip_filepaths)ifassert_only_one_file:assertnext(zip_filepaths,None)isNone,f"More than one file in{dropbox_url}"returnzip_store[first_filepath]NotesNew url-to-path mappinggrazeused to have a more straightforward url-to-local_filepath mapping,
but it ended up being problematic: In a nutshell,
if you slurpabc.comand it goes to a file of that name,
where isabc.com/data.zipsupposed to go (abc.comneeds to be a folder
in that case).Seeissue.It's with a heavy heart that I changed the mapping to one that was still
straightforward, but has the disadvantage of mapping all files to the
same file name, without extension.Hopefully a better solution will show up soon.If you already have graze files from the old way, you can
use thechange_files_to_new_url_to_filepath_formatfunction to change these
to the new format.