Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 8: File Searcher App
Lecture: Sketching out the search app
Login or
purchase this course
to watch this video and the rest of the course contents.
0:01
So let's just take a moment and sketch out the flow of this application
0:04
just to build a skeleton as we always do.
0:06
So, we have a main() method, and we'll do something here
0:09
and of course we'll use the live template from main() to call it down here, like so,
0:13
from PyCharm, and then, the next thing we want to do
0:16
of course we are going to say define print header,
0:18
what we need to do is ask the user
0:20
hey what directories subtree you want to search
0:23
and what do you want to search for,
0:25
so those are the next two things we are going to need,
0:26
we'll say get_folder_from_user(),
0:29
and similarly we'll say get_search_text_from_user().
0:34
then let's just define a search_file() method here,
0:37
and we'll figure out the parameters in a minute, ok,
0:40
we'll reformat so we are all good, via pep 8 and let's start writing,
0:44
so print_header(), you guys know this, this is old hat by now,
0:48
so we'll just fly through it,
0:57
next we are going to get a folder from the user,
0:59
we'll say get_folder_form_user() and let's just do
1:01
a quick little test like if they enter nothing we would rather not have our app crash
1:06
we'll just say hey search that, moreover,
1:10
if they enter folder that doesn't exist,
1:14
we'd also want to build the deal with this so just do a test,
1:16
and we'l leverage the truthiness of strings
1:18
so we'll say if not folder, print something like sorry we can't search that location,
1:25
now notice here is a little single quote,
1:28
this is one of those times where double quote strings are nice and handy
1:30
and then we'll just exit out of here.
1:33
Next thing is we'll get text we'll say get the text from the user
1:36
and basically exactly the same deal here boom, I can't search for nothing,
1:42
notice PyCharm has these grayed out
1:44
and that's because it knows there is no return value from that method
1:47
and yet we are trying to store in a variable, it will not crush,
1:50
it will give us the implicit return none but that is going to be highly unuseful for us,
1:55
that is kind of what the warning is,
1:57
now finally we want something like search file and over here
2:00
we'll say we want to search the folder and the text.
2:03
Now, I don't really like this name so much,
2:05
I'd rather say search files or search folders,
2:08
something like that so we can hit control t and rename this
2:11
and go I want to search folders, like that, and do the refactoring,
2:16
and down here and if there was 100 files all potentially leveraging this
2:20
and docstrings leveraging and so on,
2:22
all of that would have been fixed,
2:25
now we need our folders and text of course, excellent,
2:28
so these should be pretty easy to write,
2:29
let's just come here and pull this out,
2:32
now we are going to do a little more than just get the text that is the folder,
2:36
we are actually going to verify it.
2:38
So ask the user what folder do you want to search,
2:40
then we'll say if not folder: so for some reason it came back empty
2:43
I don't think it can ever come back as none
2:45
but let's just verify it, let's little safe and we'll say or if possibly the folder is just white space, right,
2:53
so in either case we'll just return none so we have nothing,
2:56
there is no folder and that will trigger remember up here
3:01
that will trigger this and say no, it doesn't work.
3:04
Next, let's verify that this directory exists and that we have access to it.
3:09
Again, back to our OS.path.exists,
3:14
now we can be little better, we can say isdir in case they put a file
3:17
and we are trying to search through subdirectories, or something like this,
3:20
maybe we'd write our app to behave differently
3:23
if you give it a file versus a folder, but we are not doing that right now,
3:25
so we are just going to say if it's not a directory
3:30
we'll just return none and then finally,
3:32
let's clean this up a little bit and say we'll return OS.path.absolutepath()
3:37
so we have a nice absolute path for a folder instead of something relative,
3:41
as you will see having an absolute path is helpful for later on.
3:45
Next, let's just get some search text here,
3:48
we'll say text = some sort of input again,
3:50
we'll ask what are you searching for and then we'll give
3:54
a little warning that says single phrases only,
3:57
because we are not going to do like words that mean and breaking into parts
4:01
we are just going to do basic substring searches,
4:04
that's an interesting app to write but it's not the focus
4:07
that we are really trying to get here.
4:07
So we'll just return text.
4:10
All right, it looks like things are going pretty well here,
4:13
now let's just finally do this and just do a little print statement
4:15
just to show everything is hanging together,
4:17
print would search this place for that.
4:23
So let's run ti really quick, let's just search the current directory,
4:26
it looks like I made a mistake, let's see here, not folder,
4:30
that should be or not strip, ok, perfect, ok let's try again,
4:37
I want to search the current location, and I am searching for the word cats,
4:40
so we would search/users/screencaster/desktop_08_file seracher for cats.
4:46
Perfect, so we have kind of all this parts of like user input
4:49
and everything completely done, and now
4:51
it's just a matter of implementing the search method.
