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hey everyone its anthe from pretty-pretty here in today's video I'm going to talk about how you can use the request object in flask to read incoming data that is passed to your routes so this is a video that goes along with the article I wrote on scotch so if you want to read that article as well I'll post a link to it in the description below it's going to be a little more detailed and it's going to have all the code that I write are very similar code so to start off with the request object the thing that you want to know about the request object is that it contains everything that is incoming to your end points so for example it contains the incoming data but it also contains things like headers so you know where the request is coming from information about who's sending the requests I can also come with the mind type of the request so is it just text being sent over is it a file being sent over also the HTTP method is being sent so is it a get request is it a post request is it a put request and so on and there are other things like the IP address let's say the raw data which is all the data that has the request but in a form that's not really human readable but of course the machine can read it and parse it and turn it into the request object that you deal with so in flask to ask to access this request object you simply import requests and what happens is for every request inside of your endpoint or a route whatever you want to call it this request object will have the things that are specific to that particular request so even though you're importing one thing this one thing actually changes for each request so to demonstrate the first thing I'm going to do is I'm going to create a routes and I'm going to call this query example so there are three ways of getting a request data that I want to talk about in this video one is URL parameters so query parameters another is from a form and the final one is from jason so a query example is what i'll call this and then i'll just name the the function the same thing and i'm going to use the request object in some way so the idea behind query parameters is this so first let me go to this endpoint so see query example so let me restart my server well save this first and then restart and then I go here it's a query example it says it's not found that's because I put a - instead of an underscore I want to underscore so let me try that again okay so I just get a blank page so to make that a little more clear I'll put to do here and we can see it says to do so not very interesting but what I mean by query parameters is basically this you've probably seen it in URLs before basically it starts with a question mark and then it has key value pairs separated by ampersands so like key 1 equals value 1 and person key 2 equals value 2 and so on and just add as many ampersands as you want but it always has to start with the question mark so what I'm going to do is I'm going to allow this route to read in any of those query parameters so to do that I'm going to use the request object and I'm gonna call it arcs dot get and then what I pass them to get is a string that represents the key so for example if I use language and I set this equal to language then I can say something like this so I'll make this HTML so it's going to be a header tag so it's a little bit bigger the language is and then I'll close the header tag and I'll just use format to pass in whatever language is passed in so I'll save that server should have restarted and now I'll use language as the key and the value so equals Python and I see the languages Python so I'm reading in this value from the URL in the query parameters so Python if I change this to Ruby it changes if I change this to Chango sign language PHP it changes so whatever I want to put there it will allow me to use it inside of my view function under the app route so if I want to use some more let's say framework and in this one I'm going to do something a little different so I'm going to do args but instead of using git I'm just gonna use this dictionary notation and let's say framework and then I'll do one more for website so website equals requests args gets a website and next what I'll do is I'll just I'll cover those cases in the string so I'll make this string multi-line and I'll just ask some more header tags in there so the framework is and then the website is okay just like that let me just make this look a little bit better not really too concerned with the formatting and then format language framework and website okay so there we go so now I can take in three options and we'll talk about the difference between gits and just using the brackets with the value directly so I can do an framework equals laravel and website equals PHP calm and that's not gonna work so I just use calm just so it won't crash but we see the languages PHP the framework is laravel and the website is PHP calm I didn't wanna use a period because it wouldn't be a valid URL I'll have to change it to like percents something but I don't know the encoded version of it well actually that does work so PHP calm is fine so with framework though let's see what happens if I remove website so I see the website is none so what's happening is this website is equal to none and then when it's passed in this return statement here it's getting converted to a shrink so we see none it's not very it's not very useful as something that you send to a user but that's exactly what's happening it's just the none value so you know none and python is like that but if I remove the framework let's see what happens I get this error I get a bad request qierre and what this means is that my endpoint was expecting a framework value and I didn't get it so because it didn't get something it was expecting it's saying that I have a bad request and that is very typical in cases where you know the user isn't sending the right data over so when it comes to using arcs dot get versus just arcs with the brackets is you have to decide if the data is mandatory or if it is optional if it's optional then get works if it's mandatory then you may want to use arcs because that way it's going to fail every time that data isn't there you can of course get away with using either one in the other case so for example if you use git and you still want to fail when let's say the language isn't there then you can simply write an if statement to check if language is none if it is none then you could raise that air and then likewise with the framework if you want to stop that error from happening even if framework isn't there then you just put this and try accept blocks and catch that exception and then you know do something with it without actually returning the 400 error but the default behavior for both is this will return none if it's not there this will cause a 400 error so depending on your use case you may want to use one or the other I personally like this one without the git because if I don't get all the data in a lot of cases then I can't do what I want to do inside of the function so I just want to fail completely until the user thought they didn't send the correct data but it really depends on what you're doing so that's basically query parameters now let's talk about form data so form data is another way you can send in data to a route or an endpoint or a view function whatever you want to call it they're basically the same thing practically speaking so I'll name this form example and what I'm going to do is I'm gonna return a form so method posts and then we'll do language input I can't type right now text name is language and I spelt this one wrong and I'll do the same for framework and what's the last one website you know I'll skip website because it's pretty much the same case so I'll just form like that save and I go to form example okay so I see the the two inputs there I just need a submit button so input type submit just like that okay so now what's going to happen is any time I put data in this form and hit submit it's going to post this data to the same endpoint for an example so what you don't supply in action so the action is just the URL that it posts the data to when you don't supply an action it just uses the same endpoint that generated the form so it's going to post to the same place so for this particular one I need to allow both get requests and post requests so methods is going to be post and gets and then what I want to do is do something different in each case so in the post case I want to actually use the data for something I want to look at the data that the user passed in so I'm going to use the request object again and like I said one of the things that the request object gives you is the method that is being used to call the URL so in this case it's going to be a post so when it's a post request I want to do something here and then when it's a get request I want to return the form so the user can type in data so what I'll do here is I'll return one thing if it's post data so as soon as it hits return it exits out of the function so for the post request case it gets the return it exits and it never gets to this part whereas if it's a get request and a skips this part and it returns this so just know both cases are being handled even though you only see posts here so what I want to do with posts is basically I want to process the data but first let's make sure the form is submitted so I'll put h1 tags and then now let's take a look so I'll load the thing again and I'll just put in some dummy data hit submit and it says submitted form so that's exactly what I want to see so now it's actually real data I'll use two variables again and requests and instead of Arc's since I'm using form data I want form and get and language and then for the framework pretty much the same thing but for this one I'll use the brackets so form or I should say framework at this time and then I'll display the data so the language is the framework is and then let's just throw on language and framework and hopefully I didn't misspell anything but we'll find out in just a second so the language I'll say Python and the framework I'll say flask hit submit and I did misspell something so let's see language there inside of the form let's see the name yeah so the variable language is the one that I misspelled so let's try it again Python flask hit submit and now we see the languages python the framework as flask so by submitting that form I'm able to read the foreign data in the post request and display it to the user so if I put in something else let's say language is Ruby and the framework as rails submit and we see that and then when it comes to the air so if I change this name so the name here the key here is what's being read when you use requests that form that GUID or just form so if I changes two languages from language let's see what happens so I'll use Python and flask again as an example and the language is none in the framework is flask so by simply adding that s there's no longer that key so it doesn't work so I'll remove the s and now try the same thing with framework so I put an s for framework so Python flask and then this is where I get that 400 error again so it's just like what I talked about with the query parameters if you don't use that get and the key isn't in the data then it will give you that 400 error so just keep that in mind if that's what you wants that happen you could use the brackets if you don't want that to happen then you want to use get so now what I want to do is I'm gonna fire up postman and I want to handle the case for JSON data so we'll do jason example like this so jason data is normally sent through some kind of automated process so this automated process isn't something that a person would be typing in it's something that you know code is written to handle and the reason why jason data is uses because it's a pretty neat way of it's a it's a neat way of organizing data that's easy for people to read and easy for machines to read so let me just clear out these and then i'll create a new request so here i'm basically gonna insert the URL so this is going to be the euro so the reason why I'm using postman is because I can't create JSON data through the browser so the browser is good for query parameters and for form data but for a JSON data I need to use a tool to create this so I have the tool here and I put the URL in and I'm going to make the handle let's say post requests only it can be get or post but just for example purposes I'll make this post only so we'll say methods posts so now when I go here it tells me method not allowed because through the browser this is a good request but in postman when I send this post request it gives me back the three dots so just to prove that that's what's there if I do to do again and then send them postman we see the to do down here at the bottom so now what I want to do is I want to send some data over to flask through postman so what I'm going to do is go over to body and change the data to raw and then change the type to Jason application slash Jason then I'm going to create a Jason object so jason object is pretty much just key value pairs and then it can also take in sub jason objects and then it can take in a list so I'll do a language I just cannot spell language today Python framework flask website Scotch version info so I'll make this one a list whoops actually I can make this like a sub object I think that will work better so for Python let's say three point four and then flask 1.0 so this isn't necessarily how to create a real jason object but for example purposes you'll see that this is really a really good example because the cover is pretty much all the cases so query form jason and finally boolean tests true okay so let's make sure this is a well-formed jason object so we can see the key value pairs here so we have language framework and website and then for boolean tests instead of passing in a string we pass in a boolean which is true for our version info we have like a sub json object and it has two keys python flask python let's say 3.7 and flask is 1.0 and then for examples we have query form and jason inside of an array or a list in Python so I'll send that and it still works so we know nothing went wrong there so now what we want to do is we want to actually read in that data as it comes in so I have it being sent over by postman and this can be like any other program or it can be like code that calls an API for example but to keep things simple I'm just using this tool because it's probably the best way to demonstrate it so first to get the incoming data it's a little bit different than these instead of using request I'll arcs that get or just the brackets we're in do something like this so requests data equals requests so that request object again and get JSON and now that I have that I can access the data in here so I'm going to get the language the framework I want the Python version I want one of the examples and I want the boolean value so this isn't all the data that's in my JSON object but this is some and it kind of represents you know all the different cases so to use this I use request data and then I'll get the language and then I'll do the same thing for framework now for the Python version it's going to be slightly different so first in the JSON object I'm looking for the version info key so version info and then there's a sub JSON object in there or a nested one and I want to access the Python key so just use more brackets like this Python for examples this will return the entire list so the list has three values in it and I want to get the first one so I use the zero index so just like getting any item out of the lists you just use the brackets and then the position of the item so I want the first one so I'm using 0 and then for the boolean tests it's gonna be similar to language and framework so now I simply want to display all this data so I'll use h1 tags again and this is gonna be a little longer so use the multi-line string and then I'll say the language value is the framework value is the Python version is the example at zero index is and finally the boolean value is and then just don't want format with those in the right order so language framework Python version example and boolean tests just like that let me and did all of this ok so hopefully I don't have any mistakes in there so let's try sending that again and fail to decode JSON objects so I just have an error and here somewhere line 9 it's expecting a comment so there should be a comma after that nest adjacent object so I'll send it again and then this one I spelled language wrong somewhere for some reason I just cannot spell language today so let's try that again all right so now if we look here we see the language values Python the framework values flask the Python version of 3.7 the example at zero index is query which is this and the boolean value is true so if I switch these up a little bit let's say false and then the language Ruby rails change the Python version to 3.4 and then run it we see things have changed so Ruby rails 3.4 for Python the example at 0 index is so query I'll have to change that in the code and the boolean value is false so if I change this to let's say 2 instead of 0 and then run it again then we get JSON because that is at the other position so the last thing is if you want to handle data that's not is going to be there then here's how you can do it you can set one of the values to be none so do it for language so language equals none I mean I'll say if language in request data so if it finds the language in the request data then assign the language to that value and if it doesn't find it then it just remains as none so let's try that so it still works now remove the language run it and we see the value is none so because there's no dot get equivalent we have to do the check but with JSON objects is really more useful to do it like this because you're expecting the data to come from a machine so it should be fairly consistent and it should cover all the cases that you are interested in handling so if the data isn't there and you expect it to be there then there should be some kind of error you shouldn't just let it go on because you're expecting the data from a machine but of course if you have a use case where you know maybe the data doesn't have to be there then you can consider other approaches but generally speaking JSON data is normally pretty consistent and if you expect values to be optional then you just do something like this so those are the three main ways of receiving requests data in flask obviously there are other things that you can get from the request object but these are probably the most common ones that she'll be using so that's all I wanted to cover in this video like I said if you want to read the article that's associated with this video you can go to the link in the description below if you liked this video please give me a thumbs up if you haven't subscribe to my channel already please subscribe and if you have any questions about this video feel free to leave a comment down below so thank you for watching and I will talk to you next time