Spring MVC Tutorials 34 - Web Services 04 ( Important JSON REST API Annotations...) Video Lecture | MVC Tutorials: Web Programming Course - Web Development

guys my name is Hamish Karev and I will
commit with Conte
series in the previous tutorial we
learnt how to create a basic REST API by
making yourself response body annotation
over this controller method so after
performing all the steps as specified in
the previous tutorial now when any user
is going to make a get request using
this REST API the request is going to be
received by this controller method and
here because we are making a
self-response poly annotation over this
controller method it's simply going to
indicate spring MVC framework not to
make use of any view technology while
preparing the final response instead it
is supposed to be returning the return
value of this function directly to the
client as a response now while returning
this directly to the client if spring
MVC framework is going to detect JSON
related charge on to the projects class
path which we included in the last
session it's going to convert this cell
object into its equivalent jisan text
and then same is going to be returned to
the client as a response after I make a
get request I get this JSON text as a
response from the application and
whatever I've just described in a very
brief manner I explain in detail in the
previous tutorial now let's proceed
further learn how to have a little more
control over the JSON response that we
have a seed here from the application so
let's start because if you observe this
JSON response what we have received from
the application you would find that it
has sent us three rows first row and
then second row and then third row and
in each row in this JSON response it has
included certain key value pairs to the
name then it's value student hobby
it's valium and so on now what all key
value pairs it has included here
well whatever properties we have inside
student class student name student hobby
and so on and that's what it has
included in each row for some reason
what if you want to alter the name of
keys what it has included in each row in
this JSON response let's suppose you
want to alter student name - student
underscore name or student hobby - just
hobby how to do that well in spring can
be safely work it's very easy task guys
all you need to do is whichever property
name you want to alter simply specify
JSON property annotation on top of it
and pass the desired name as an argument
to it suppose I want to change to the
name - student underscore name so what's
going to happen after this small change
now when I'm going to make a get request
using this first API I expect that in
each row it's not going to include
through a name but student underscore
name
so let's very quickly check this out
see now it has a included student
underscore name and earlier it included
student name key in each row because if
you look at DCM JSON response you know
each row in this JSON response you would
find that spring MVC framework has used
its on ordering mechanism you know to
list the key value pairs so it has
listed student hobby first then mobile
and then data birth so it has used its
on mechanism while choosing which key
value pair has to be displayed first ad
which has to be displayed next now what
if you want to have a little more
control over this order you want to
provide your own customized order as per
your project requirement
so how to achieve that let's suppose
here what if we want data birth key
value pair to be listed you know at the
first and then maybe student name key
value the second and in other properties
in some sequence how to achieve that
well in spring MVC framework that's kind
of very easy job to perform guys you are
just required to make use of the
annotation geo some property order on
top of this class and inside it just go
on specifying the order in which you
want key value pairs to be displayed in
each row suppose we want student do be
key to be listed at the first position
in each row and then let's suppose we
want student name and then screen mobile
and then address and then hobby and then
skills so this is the way to achieve
that using JSON property orders
annotation so after making this small
change now when I am going to make a
request again I expect that it's going
to list key value pairs in the order as
I have specified in the student class
let's check this out cool it has a
lifted now all the key value pairs the
way I have instructed it to follow in
the student class data birth then name
then mobile dan adversity leader bird
then name then mobile and then address
and hobby and then skills habían in
skills so it has followed the order
exactly the way I instructed instructed
it using JSON property order annotation
now in the same JSON response if you
observe in each row it's displaying all
the keys and the corresponding values
whatever you know against all the
properties what you have in this student
class
now for some reason what if you want
to instruct spring MVC female not to
include any specific property in the
JSON response let's suppose you don't
want student skills property to be used
in the JSON response you don't want
student skills key value pair in each
record so how to do that we're in spring
MSE female that's kind of very easy to
optical some guys again on top of the
class specify an annotation JSON ignore
properties and inside it just go on
specifying what all properties of this
student class you don't want spring MVC
framework to make resolve while
preparing the JSON response let's
suppose I don't want student skills key
value pairs to be included in the JSON
response so I would specify it just like
this so after making this change now if
I make a get request I expect that it's
not going to improve student skills ki
and its value in each row let's check it
out cool see this is no wait has
included student skills in the first
Sakata and same is true for the second a
quad and same is true for third record
so the idea is whichever property or
properties you want to exclude from the
JSON response simply go on specifying
here suppose here I want to instruct
spring MVC FEMA to exclude one more key
value pairs you know again student
address property so this is the way to
achieve it so after this now in the JSON
response it's not going to include
students skills as less student address
so whichever property or properties you
want spring msec will exclude from the
JSON response go on specifying it as an
argument to chase one ignore properties
annotation and you will be done right
now
one last
concept and we are going to wind up
today's session because if you look at
this JSON response going to eat each row
you observe for most of the key is we
are getting null as the value and why we
are getting null as the value it's
simply because that's what we have set
over here so whatever we are going to
set over here in each student record
same is what we are going to get here so
because we are setting only name so we
are getting a valid value for these two
underscore name key and for others
because we are not setting so we are
getting none value so whichever property
we are not setting in the controller
method for that we are getting none at
the value it simply indicates that there
is no valid value spring MVC framework
found for this spawning key now what if
you have a very special requirement in
your project what you want to achieve is
while preparing the JSON response if
spring MVC framework finds that a
certain key has got a valid null then
you want spring MVC framework not to
include such key value pairs so you want
string everything work not to include a
key in the JSON respond and its
corresponding value if you know that key
has got null as its value how to achieve
that well again that's kind of very easy
job to perform guys in the student class
just go and specify JSON include
annotation coincide it is an argument to
that just write JSON include include dot
non null and you are done so with this
annotation JSON include and this
argument to that you are instructing
spring a position work a spring and
missing work while preparing teachers on
response if you observe any keys value
has none
then simply excluded from the JSON
response so here if you observe expect
accept student name all of the keys have
got null as the value so what it's going
to do after making this change
well it's going to include all those
keys it has got which have got none as
the values so now let's make a get
request again on this same URI rest URI
see it has sent us key in 3d cards but
in each record it has included only
student underscore name so it has
included now only those keys which have
got valid values other than null value
so all null value keys it has excluded
from the JSON response and all that has
happened because of this annotation JSON
include with this argument so in this
tutorial we learned how to have more
control over the JSON response what
application prickers and send to the
client when the client makes any request
using some interest
ura in the next tutorial we are going to
talk about how to make use of an
advanced level testing tool for REST API
known with the name postman and in
addition to that we are also going to
talk about some more important REST API
concepts like a request param path
variable and many more guys a big thank
you for learning spring MVC restful Web
Services concepts with me if you have
any feedback or comments please provide
them below the video or simply write to
me on this email id for all of your
creators please hit the like button if
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series and I'm going to catch you the
next part of this tutorial