1. 概述

在本文中，我們將擴展我們在上一系列文章中開發的 REST 查詢語言，以包含更多搜索操作

我們現在支持以下操作：相等、否定、大於、小於、以...開頭、以...結尾、包含和 LIKE。

請注意，我們探索了三種實現方式——JPA Criteria、Spring Data JPA Specifications 和 Query DSL；在本文中，我們將繼續使用 Specifications，因為它是一種清晰且靈活的方式來表示我們的操作。

2. The SearchOperation 枚舉首先，讓我們通過枚舉來定義更好的表示我們的各種支持的搜索操作：

public enum SearchOperation {
    EQUALITY, NEGATION, GREATER_THAN, LESS_THAN, LIKE, STARTS_WITH, ENDS_WITH, CONTAINS;

    public static final String[] SIMPLE_OPERATION_SET = { ":", "!", ">", "<", "~" };

    public static SearchOperation getSimpleOperation(char input) {
        switch (input) {
        case ':':
            return EQUALITY;
        case '!':
            return NEGATION;
        case '>':
            return GREATER_THAN;
        case '<':
            return LESS_THAN;
        case '~':
            return LIKE;
        default:
            return null;
        }
    }
}

我們有兩個操作集：

1. 簡單 – 可以用一個字符表示：

相等：用冒號（:）表示

否定：用感嘆號（!）表示

大於：用（>）表示

小於：用（<）表示

像：用波浪線（~）表示

2. 複雜 – 需要多於一個字符才能表示：

以開頭：用（=prefix*）表示

以結尾：用（=*suffix）表示

包含：用（=*substring*）表示

我們還需要修改我們的 SearchCriteria 類以使用新的 SearchOperation：

public class SearchCriteria {
    private String key;
    private SearchOperation operation;
    private Object value;
}

3. 修改 UserSpecification

現在，讓我們將新支持的操作包含到我們的 UserSpecification 實現中:

public class UserSpecification implements Specification<User> {

    private SearchCriteria criteria;

    @Override
    public Predicate toPredicate(
      Root<User> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
    
        switch (criteria.getOperation()) {
        case EQUALITY:
            return builder.equal(root.get(criteria.getKey()), criteria.getValue());
        case NEGATION:
            return builder.notEqual(root.get(criteria.getKey()), criteria.getValue());
        case GREATER_THAN:
            return builder.greaterThan(root.<String> get(
              criteria.getKey()), criteria.getValue().toString());
        case LESS_THAN:
            return builder.lessThan(root.<String> get(
              criteria.getKey()), criteria.getValue().toString());
        case LIKE:
            return builder.like(root.<String> get(
              criteria.getKey()), criteria.getValue().toString());
        case STARTS_WITH:
            return builder.like(root.<String> get(criteria.getKey()), criteria.getValue() + "%");
        case ENDS_WITH:
            return builder.like(root.<String> get(criteria.getKey()), "%" + criteria.getValue());
        case CONTAINS:
            return builder.like(root.<String> get(
              criteria.getKey()), "%" + criteria.getValue() + "%");
        default:
            return null;
        }
    }
}

4. 存在持久性測試

接下來，我們測試我們的新搜索操作 – 在持久性級別：

4.1. 測試相等性

在下面的示例中 – 我們將搜索一個用户 通過他們的名字和姓氏：

@Test
public void givenFirstAndLastName_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.EQUALITY, "john"));
    UserSpecification spec1 = new UserSpecification(
      new SearchCriteria("lastName", SearchOperation.EQUALITY, "doe"));
    List<User> results = repository.findAll(Specification.where(spec).and(spec1));

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

4.2. 測試否定

接下來，我們搜索那些名字通過 他們的名字不“john”的用户：

@Test
public void givenFirstNameInverse_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.NEGATION, "john"));
    List<User> results = repository.findAll(spec);

    assertThat(userTom, isIn(results));
    assertThat(userJohn, not(isIn(results)));
}

4.3. 測試大於

接下來，我們將搜索年齡大於“25”的用户：

@Test
public void givenMinAge_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("age", SearchOperation.GREATER_THAN, "25"));
    List<User> results = repository.findAll(Specification.where(spec));

    assertThat(userTom, isIn(results));
    assertThat(userJohn, not(isIn(results)));
}

4.4. 測試開始於

接下來，我們搜索那些名字以“jo”開始的用户：

@Test
public void givenFirstNamePrefix_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.STARTS_WITH, "jo"));
    List<User> results = repository.findAll(spec);

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

4.5. 測試結束於

接下來，我們搜索那些名字以“n”結束的用户：

@Test
public void givenFirstNameSuffix_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.ENDS_WITH, "n"));
    List<User> results = repository.findAll(spec);

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

4.6. 測試包含

現在，我們搜索那些名字包含“oh”的用户：

@Test
public void givenFirstNameSubstring_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("firstName", SearchOperation.CONTAINS, "oh"));
    List<User> results = repository.findAll(spec);

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

4.7. 測試範圍

最後，我們搜索年齡在“20”和“25”之間的用户：

@Test
public void givenAgeRange_whenGettingListOfUsers_thenCorrect() {
    UserSpecification spec = new UserSpecification(
      new SearchCriteria("age", SearchOperation.GREATER_THAN, "20"));
    UserSpecification spec1 = new UserSpecification(
      new SearchCriteria("age", SearchOperation.LESS_THAN, "25"));
    List<User> results = repository.findAll(Specification.where(spec).and(spec1));

    assertThat(userJohn, isIn(results));
    assertThat(userTom, not(isIn(results)));
}

5. 用户規格構建器

現在持久化已完成並經過測試，讓我們將注意力集中在 Web 層上。

我們將在此前文章的 用户規格構建器 實現上進行擴展，以 集成新的搜索操作：

public class UserSpecificationsBuilder {

    private List<SearchCriteria> params;

    public UserSpecificationsBuilder with(
      String key, String operation, Object value, String prefix, String suffix) {
    
        SearchOperation op = SearchOperation.getSimpleOperation(operation.charAt(0));
        if (op != null) {
            if (op == SearchOperation.EQUALITY) {
                boolean startWithAsterisk = prefix.contains("*");
                boolean endWithAsterisk = suffix.contains("*");

                if (startWithAsterisk && endWithAsterisk) {
                    op = SearchOperation.CONTAINS;
                } else if (startWithAsterisk) {
                    op = SearchOperation.ENDS_WITH;
                } else if (endWithAsterisk) {
                    op = SearchOperation.STARTS_WITH;
                }
            }
            params.add(new SearchCriteria(key, op, value));
        }
        return this;
    }

    public Specification<User> build() {
        if (params.size() == 0) {
            return null;
        }

        Specification result = new UserSpecification(params.get(0));
     
        for (int i = 1; i < params.size(); i++) {
            result = params.get(i).isOrPredicate()
              ? Specification.where(result).or(new UserSpecification(params.get(i))) 
              : Specification.where(result).and(new UserSpecification(params.get(i)));
        }

        return result;
    }
}

6. The UserController

接下來，我們需要修改我們的 UserController 以正確地解析新的操作：

@RequestMapping(method = RequestMethod.GET, value = "/users")
@ResponseBody
public List<User> findAllBySpecification(@RequestParam(value = "search") String search) {
    UserSpecificationsBuilder builder = new UserSpecificationsBuilder();
    String operationSetExper = Joiner.on("|").join(SearchOperation.SIMPLE_OPERATION_SET);
    Pattern pattern = Pattern.compile(
      "(\\w+?)(" + operationSetExper + ")(\p{Punct}?)(\\w+?)(\p{Punct}?),");
    Matcher matcher = pattern.matcher(search + ",");
    while (matcher.find()) {
        builder.with(
          matcher.group(1), 
          matcher.group(2), 
          matcher.group(4), 
          matcher.group(3), 
          matcher.group(5));
    }

    Specification<User> spec = builder.build();
    return dao.findAll(spec);
}

我們可以現在調用API並獲得與任何組合的條件相匹配的結果。例如——以下是使用API和查詢語言的複雜操作的示例：

http://localhost:8082/spring-rest-query-language/auth/users?search=firstName:jo*,age<25

響應：

[{
    "id":1,
    "firstName":"john",
    "lastName":"doe",
    "email":"[email protected]",
    "age":24
}]

7. Tests for the Search API

Finally – let’s make sure our API works well by writing a suite of API tests.

We’ll start with the simple configuration of the test and the data initialization:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(
  classes = { ConfigTest.class, PersistenceConfig.class },
  loader = AnnotationConfigContextLoader.class)
@ActiveProfiles("test")
public class JPASpecificationLiveTest {

    @Autowired
    private UserRepository repository;

    private User userJohn;
    private User userTom;

    private final String URL_PREFIX = "http://localhost:8082/spring-rest-query-language/auth/users?search=";

    @Before
    public void init() {
        userJohn = new User();
        userJohn.setFirstName("John");
        userJohn.setLastName("Doe");
        userJohn.setEmail("[email protected]");
        userJohn.setAge(22);
        repository.save(userJohn);

        userTom = new User();
        userTom.setFirstName("Tom");
        userTom.setLastName("Doe");
        userTom.setEmail("[email protected]");
        userTom.setAge(26);
        repository.save(userTom);
    }

    private RequestSpecification givenAuth() {
        return RestAssured.given().auth()
                                  .preemptive()
                                  .basic("username", "password");
    }
}

7.1. Test Equality 
First – let’s search for a user with the first name “john” and last name “doe”:
@Test
public void givenFirstAndLastName_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:john,lastName:doe");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

7.2. Test Negation 
Now – we’ll search for users when their first name isn’t “john”:
@Test
public void givenFirstNameInverse_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName!john");
    String result = response.body().asString();

    assertTrue(result.contains(userTom.getEmail()));
    assertFalse(result.contains(userJohn.getEmail()));
}

7.3. Test Greater Than 
Next – we will look for users with age greater than “25”:
@Test
public void givenMinAge_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "age>25");
    String result = response.body().asString();

    assertTrue(result.contains(userTom.getEmail()));
    assertFalse(result.contains(userJohn.getEmail()));
}

7.4. Test Starts With 
Next – users with their first name starting with “jo”:
@Test
public void givenFirstNamePrefix_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:jo*");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

7.5. Test Ends With 
Now – users with their first name ending with “n”:
@Test
public void givenFirstNameSuffix_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:*n");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

7.6. Test Contains 
Next, we’ll search for users with their first name containing “oh”:
@Test
public void givenFirstNameSubstring_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "firstName:*oh*");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}

7.7. Test Range 
Finally, we’ll search for users with ages between “20” and “25”:
@Test
public void givenAgeRange_whenGettingListOfUsers_thenCorrect() {
    Response response = givenAuth().get(URL_PREFIX + "age>20,age<25");
    String result = response.body().asString();

    assertTrue(result.contains(userJohn.getEmail()));
    assertFalse(result.contains(userTom.getEmail()));
}


8. 結論
在本文中，我們將 REST Search API 的查詢語言向前推進到一個成熟、經過測試的生產級實現。 我們現在支持各種各樣的操作和約束，這應該使我們能夠優雅地跨越任何數據集，並獲取我們正在尋找的精確資源。

 

  

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