{"id":97,"date":"2019-03-07T06:55:34","date_gmt":"2019-03-07T06:55:34","guid":{"rendered":"https:\/\/www.kindsonthegenius.com\/spring-boot\/?p=97"},"modified":"2020-07-26T08:13:13","modified_gmt":"2020-07-26T08:13:13","slug":"11-spring-boot-get-item-by-id","status":"publish","type":"post","link":"https:\/\/kindsonthegenius.com\/spring-boot\/11-spring-boot-get-item-by-id\/","title":{"rendered":"Spring Boot – Get Item by Id"},"content":{"rendered":"

In this chapter, we are going to write the methods to get resources by Id.<\/p>\n

Remember that in the previous chapter(Write GET Methods)<\/a>, we wrote methods, to get all resources. For example, getAllUsers, getAllPosts and getAllLocation. But this time we would write methods for getUser, getPost and getLocation.<\/p>\n

This methods would take parameter, which is the id of the item to get.<\/p>\n

 <\/p>\n

    \n
  1. Get a Single User<\/a><\/li>\n
  2. Get a Single Post<\/a><\/li>\n
  3. Get a Single Location<\/a><\/li>\n
  4. Test the Application<\/li>\n<\/ol>\n

     <\/p>\n

    1. Get a Single User<\/strong><\/h4>\n

    So this method would be written in the UserService file. We call this method GetUser. On way to do this is to loop through the user and find a match for the passed in id parameter. But in this tutorial we would use the stream API.<\/p>\n

    The method is as shown below:<\/p>\n

     <\/p>\n

    public<\/span> User getUser<\/span>(<\/span>String id)<\/span> {<\/span>\r\n    User user =<\/span> users.<\/span>stream<\/span>()<\/span>\r\n\t\t.<\/span>filter<\/span>(<\/span>t -> id<\/span>.<\/span>equals<\/span>(<\/span>t.<\/span>getId<\/span>()))<\/span>\r\n\t\t.<\/span>findFirst<\/span>()<\/span>\r\n\t\t.<\/span>orElse<\/span>(<\/span>null<\/span>);<\/span>\r\n\t\t\r\n    return<\/span> user;<\/span>\r\n}<\/span>\r\n<\/pre>\n
    Listing 1.0: getUser Method using Stream API<\/p>\n
     <\/p>\n
    Now, we go to the UserController. We’ll write a method that handles a request to \/User\/id<\/em>. For example the request to \/User\/u1<\/em> should return the user with id of u1. Similarly request to \/User\/u2<\/em> should return the user with id of u2. And so on.<\/p>\n
    The method is shown below<\/p>\n
     <\/p>\n
    <\/p>\n
    @RequestMapping<\/span>(<\/span>value =<\/span> \"\/users\/{id}\"<\/span>)<\/span>\r\npublic<\/span> User getUser<\/span>(<\/span>@PathVariable<\/span> String id)<\/span> {<\/span>\r\n    return<\/span> userService.<\/span>getUser<\/span>(<\/span>id);<\/span>\r\n}<\/span>\r\n<\/pre>\n
     <\/p>\n
     <\/p>\n
    2. Get a Single Post<\/strong><\/h4>\n
    We then write the methods to return a single post. It follows the same pattern as returning a single user.<\/p>\n
    The method for the PostService is given below;<\/p>\n
     <\/p>\n
    public<\/span> Post getPost<\/span>(<\/span>String id)<\/span> {<\/span>\r\n    \tPost post =<\/span> posts.<\/span>stream<\/span>()<\/span>\r\n\t\t.<\/span>filter<\/span>(<\/span>t -><\/span> id.<\/span>equals<\/span>(<\/span>t.<\/span>getId<\/span>()))<\/span>\r\n\t\t.<\/span>findFirst<\/span>()<\/span>\r\n\t\t.<\/span>orElse<\/span>(<\/span>null<\/span>);<\/span>\r\n\t\t\r\n\treturn<\/span> post;<\/span>\r\n}<\/span>\r\n<\/pre>\n
     <\/p>\n
    The method for the PostController is given below as well<\/p>\n
     <\/p>\n
    <\/p>\n
    @RequestMapping<\/span>(<\/span>value =<\/span> \"\/posts\/{id}\"<\/span>)<\/span>\r\npublic<\/span> Post getPost<\/span>(<\/span>@PathVariable<\/span> String id)<\/span> {<\/span>\r\n    return<\/span> postService.<\/span>getPost<\/span>(<\/span> id);<\/span>\r\n}<\/span>\r\n<\/pre>\n
     <\/p>\n
     <\/p>\n
    3. Get a Single Location<\/strong><\/h4>\n
    In the same way, we write the getLocation method for the LocationService and LocationController files.<\/p>\n
     <\/p>\n
    Put the code below in the LocationService class<\/p>\n
    public<\/span> Location getLocation<\/span>(<\/span>String id)<\/span> {<\/span>\r\n    Location location =<\/span> locations.<\/span>stream<\/span>()<\/span>\r\n\t.<\/span>filter<\/span>(<\/span>t -><\/span> id.<\/span>equals<\/span>(<\/span>t.<\/span>getId<\/span>()))<\/span>\r\n\t.<\/span>findFirst<\/span>()<\/span>\r\n\t.<\/span>orElse<\/span>(<\/span>null<\/span>);<\/span>\r\n\t\t\r\n    return<\/span> location;<\/span>\r\n}<\/span>\r\n<\/pre>\n
     <\/p>\n
    Put the code below in the LocationController class<\/p>\n
    <\/p>\n
    @RequestMapping<\/span>(<\/span>value =<\/span> \"\/locations\/{id}\"<\/span>)<\/span>\r\npublic<\/span> Location getLocation<\/span>(<\/span>@PathVariable<\/span> String id)<\/span> {<\/span>\r\n\treturn<\/span> locationService.<\/span>getLocation<\/span>(<\/span>id);<\/span>\r\n}<\/span>\r\n<\/pre>\n
     <\/p>\n
     <\/p>\n
    4. Test the Application<\/strong><\/h4>\n
    Now, it’s time to test the application.<\/p>\n
    So right-click on the application. Choose Run As > Spring Boot Application<\/p>\n
    Then Open the browser and visit the following urls:<\/p>\n
      \n
    • http:\/\/localhost:8080\/users\/u1<\/li>\n
    • http:\/\/localhost:8080\/posts\/p1<\/li>\n
    • http:\/\/localhost:8080\/locations\/l1<\/li>\n<\/ul>\n
      If you have any challenges, please mention it in the comment box below.<\/p>\n","protected":false},"excerpt":{"rendered":"
      In this chapter, we are going to write the methods to get resources by Id. Remember that in the previous chapter(Write GET Methods), we wrote … <\/p>\n","protected":false},"author":1,"featured_media":98,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[2],"tags":[],"class_list":["post-97","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-spring-boot-tutorials"],"_links":{"self":[{"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/posts\/97","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/comments?post=97"}],"version-history":[{"count":4,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/posts\/97\/revisions"}],"predecessor-version":[{"id":233,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/posts\/97\/revisions\/233"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/media\/98"}],"wp:attachment":[{"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/media?parent=97"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/categories?post=97"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kindsonthegenius.com\/spring-boot\/wp-json\/wp\/v2\/tags?post=97"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}