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