Hey there, welcome back friends. Till now we have created this particular method, which returns us a list of all the posts, right and if I show you the service method, in here we have a list. And now we will try to implement a yet another functionality in our macro service and our functionality will indeed return a specific entity from the list. So in here, for example, if we pass on three ID on the URL, based on a specific pattern, then we should get information related to the post with ID three only. Alright, so first of all, let us implement a method in order to get the information for a specific ID. This would be a yet another public method.
This will return an object of post type and the name would be get post and it is an entity server will receive an entity with the name of ID All right, and the body of this particular method would be again very simple. So, we will simply tap and return new post service dot get paused and we will pass on the ID. Now, if we hover upon this particular method, the method is not present inside of a service. So, let us quickly create this method First of all, now, we will add the business logic inside this get POST method later, but first of all let us fix the request mapping part of this method itself. So, let us add on the request mapping annotation and this time the mapping would be slash posts slash ID. Now, friends here is a catch.
Now this ID is what this is is nothing but a variable. We can, for example, pass on the URL as post slash three. And we should get information related to the post with ID three. Now, if we simply give this particular URL pattern, this is a string. So how Spring Boot will know that this particular string part is nothing but an ID? And the answer is braces.
So if we enclosed this particular part as a braces, then a Spring Boot will get notified that this particular part of the URL has nothing but the specific variable a get variable using which we can read the information. Right. Now, friends, reading the information is one thing. Spring Boot knows that this particular part on the URL is nothing but a specific variable. But now we need to initialize this parameter ID as well and we need to somehow assign the value which is received from the user Added to this variable. In order to perform this task, we have a yet another annotation, the name of the annotation is PATH variable.
Here we go. And at this particular annotation will automatically auto wire, this ID to this parameter ID. Now for example, there is a inconsistency in the name of the variable. For example, this variable is temp, ID. Now this seems to be good enough. And if I make few more changes, there is no syntax related issue.
But there is an issue in here this code will not get executed properly, the name of the aliases ID whereas the name of the variable as a parameter is temp it there is an inconsistency. Now in order to fix that, we need to explicitly tell our annotation PATH variable annotation that the name of the alias is ID and the reason Very simple, we will make use of pair of parentheses and we will provide the name of the variable as ID and our work should be done. Now friends handling the situation in this way is good enough but it is not recommended. It is always good to give the name of the alias and the name of the variable as seen and let Spring Boot auto wire these two variable so, in here I will get rid of this pair of parenthesis and we will undo the changes we will make this variable as ID and we will also pass on the ID to our method All right.
So, this is good now let us navigate to our method. In here as of now there is no body and handling or adding the logic inside this method is very simple. We will add in a for each loop. This loop would be based on our object post. The name of the temporary variable can be paused again and we will iterate on our list whose name is Paul. All right and in between pair of braces we will add an if condition and the if condition would be f post dot get post ID equal to equal to ID in this case, we will simply return the post, right and if the iteration ends then finally we will return null and our work would be done.
All right. So now let us quickly run this application on our web server. In fact, we will run the application in the Embedded Web Server right. So, Spring Boot is now running on the embedded Tomcat. And it is up and running. Let us minimize the console and let us navigate to Google Chrome and we'll navigate to first of all the URL localhost colon 8080 slash post and here is the JSON response.
This is the entire list and now we will try to access it Post with ID four where the title is access specifier right so if I navigate to localhost colon 8080 slash post slash four then we should get a response and here is the response perfect. All right. Now let me also do one small little thing. Let me For example, navigate to it which does not exist, then we should get a blank output, which is perfect, nice, good. And our application is working as it should. Everything is good enough.
Nice, good. Alright, so that's it for today, and we will check out a couple of more things in our forthcoming videos. Thanks for watching. Have a nice day and take care