使用REST API输入在基于Spring Boot的应用程序中在运行时设置架构名称

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英文:

Set schema name at run time using REST API input in spring boot based application

问题

**postgres** 数据库中**模式名称** 被设定为 **买家 ID**因此如果买家 ID 是 *buyer_2213*那么模式名称将是 *buyer_2213*)。这些模式拥有多个表而且这些表在所有模式中都有共同的结构

现在我正在使用 Spring Boot 编写 REST API以从这些模式中获取买家数据但由于 *模式名称* 取决于 *买家 ID*我不得不编写手动查询无法使用 JPA 的功能

是否有任何方法可以使用 REST API 请求参数来设置实体的 **模式名称**因此在下面的实体中是否可以通过在 BuyerController 中定义的 API 调用时使用传递的 *buyerId* 来设置 *schema*

```java
  @Entity
  @Table(name="buyer_table", schema="使用_API输入设置")
  public class BuyerTable{
    ...
  }

  @RestController
  @RequestMapping("/buyer")
  public class BuyerController{
    
    @GetMapping("/{buyerId}")
    public void getBuyerData(@PathVariable(required = true) String buyerId){
      ...
    }
  }

此外,买家 ID 与已登录用户不同(将此情况视为正在尝试获取买家详细信息的管理员用户),并且仅将其作为 API 请求参数(或任何其他方式作为 API 输入)提供。因此,我无法找到与 此链接 的相关性。


<details>
<summary>英文:</summary>

In a **postgres** database, the **schema name** is set as the **buyer id**(so, if buyer id is *buyer_2213* then schema name will be *buyer_2213*). These schemas have multiple tables and these tables have common structure for all schemas. 

Now, I am writing REST API using spring boot to get buyer data from these schema, but since *schema name* is *buyer id* dependent, I have to write manual queries and could not use JPA features for that.

Is there any way to set **schema name** to entity using REST API request parameters. So, in below entity, can we set *schema* using *buyerId* passed at API call defined in BuyerController:

@Entity
@Table(name="buyer_table", schema="set_it_using_API_input")
public class BuyerTable{
...
}

@RestController
@RequestMapping("/buyer")
public class BuyerController{

@GetMapping(&quot;/{buyerId}&quot;)
public void getBuyerData(@PathVariable(required = true) String buyerId){
  ...
}

}


Also, the buyer Id is not same as logged in user(consider this situation as admin user who is trying to get buyer&#39;s details) and will be provided as API request param only(or any other way as API input). Hence I could not find relevance to [this][1]


  [1]: https://stackoverflow.com/questions/39357367/change-database-schema-during-runtime-based-on-logged-in-user

</details>


# 答案1
**得分**: 1

我终于找到了一个可行的解决方案。此解决方案主要使用[这里][1]的配置,但更符合我的问题要求。&lt;br/&gt;&lt;br/&gt;
显然的想法是使用[AbstractDataSource][2],数据源配置与[这里][1]显示的几乎相同,只需使用可以从API逻辑内部调用的 *setter* 来设置模式名称。&lt;br/&gt;
首先,我们需要编写一个**AbstractDataSource**的实现,它将几乎看起来像这样:

```java
public class BuyerSchemaDataSource extends AbstractDataSource {

    private LoadingCache&lt;String, DataSource&gt; dataSources = createCache();

    public void setSchemaName(String schemaName){
        this.schemaName = schemaName;
    }

    @Override public Connection getConnection() throws SQLException {
        try {
            return determineTargetDataSource().getConnection();
        } catch (ExecutionException e) {
            //打印异常
            return null;
        }
    }

    @Override public Connection getConnection(String username, String password)
        throws SQLException {
        try {
            return determineTargetDataSource().getConnection(username,password);
        } catch (ExecutionException e) {
            //打印异常
            return null;
        }
    }

    private DataSource determineTargetDataSource() throws ExecutionException {
        if(!utils.isNullOrEmpty(schemaName)){
            return dataSources.get(schemaName);
        }
        return buildDataSourceFromSchema(null);
    }

    private LoadingCache&lt;String, DataSource&gt; createCache(){
        return CacheBuilder.newBuilder()
            .maximumSize(100)
            .expireAfterWrite(10, TimeUnit.MINUTES)
            .build(new CacheLoader&lt;String, DataSource&gt;() {
                @Override public DataSource load(String key) throws Exception {
                    return buildDataSourceFromSchema(key);
                }
            });
    }

    private DataSource buildDataSourceForSchema(String schema) {
        // 例如属性的示例: "jdbc:postgresql://localhost:5432/mydatabase?currentSchema="
        String url = env.getRequiredProperty("spring.datasource.url") + schema;
        return DataSourceBuilder.create()
            .driverClassName(env.getRequiredProperty("spring.datasource.driverClassName"))
            [...]
            .url(url)
            .build();
    }
}

<br/>
现在,就像任何其他数据源一样,这可以在Spring配置文件中使用,如下所示:<br/>

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef = "schemaSpecificEntityManagerFactory",
    transactionManagerRef = "schemaSpecificTransactionManager")
public class SchemaSpecificConfig {

    @Bean(name = "schemaSpecificDataSource")
    public DataSource schemaSpecificDataSource(){
        return new BuyerSchemaDataSource();
    }

    @Bean(name = "schemaSpecificEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean schemaSpecificEntityManagerFactory(
        EntityManagerFactoryBuilder builder, @Qualifier("schemaSpecificDataSource") DataSource dataSource) {

        HashMap<String, Object> properties = new HashMap<>();
        properties.put("hibernate.hbm2ddl.auto", "update");
        properties.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
        return builder.dataSource(dataSource).properties(properties)
            .persistenceUnit("SchemaSpecific").build();
    }

    @Bean(name = "schemaSpecificTransactionManager")
    public PlatformTransactionManager schemaSpecificTransactionManager(
        @Qualifier("schemaSpecificEntityManagerFactory") EntityManagerFactory schemaSpecificEntityManagerFactory) {
        return new JpaTransactionManager(schemaSpecificEntityManagerFactory);
    }
}

<br/>
现在,在控制器的API逻辑内部可以调用BuyerSchemaDataSource中定义的setSchema()方法。<br/><br/>
这看起来像是一个解决方法不太好的问题,但我没有找到比这更好的方法,欢迎所有建议/编辑。

英文:

I've finally found a working solution for this. This solution uses configurations mostly from here but is more specific to the my question requirements. <br/><br/>
The idea is obviously to use AbstractDataSource and data source configurations are pretty much similar to what shown in here with just the schema name will be set using a setter which can be called from inside API logic.<br/>
First, we need to write an implementation of AbstractDataSource which will pretty much look like this:

public class BuyerSchemaDataSource extends AbstractDataSource {

    private LoadingCache&lt;String, DataSource&gt; dataSources = createCache();

    public void setSchemaName(String schemaName){
        this.schemaName = schemaName;
    }

    @Override public Connection getConnection() throws SQLException {
        try {
            return determineTargetDataSource().getConnection();
        } catch (ExecutionException e) {
            //print exception
            return null;
        }
    }

    @Override public Connection getConnection(String username, String password)
        throws SQLException {
        try {
            return determineTargetDataSource().getConnection(username,password);
        } catch (ExecutionException e) {
            //print exception
            return null;
        }
    }

    private DataSource determineTargetDataSource() throws ExecutionException {
        if(!utils.isNullOrEmpty(schemaName)){
            return dataSources.get(schemaName);
        }
        return buildDataSourceFromSchema(null);
    }

    private LoadingCache&lt;String, DataSource&gt; createCache(){
        return CacheBuilder.newBuilder()
            .maximumSize(100)
            .expireAfterWrite(10, TimeUnit.MINUTES)
            .build(new CacheLoader&lt;String, DataSource&gt;() {
                @Override public DataSource load(String key) throws Exception {
                    return buildDataSourceFromSchema(key);
                }
            });
    }

    private DataSource buildDataSourceForSchema(String schema) {
        // e.g. of property: &quot;jdbc:postgresql://localhost:5432/mydatabase?currentSchema=&quot;
        String url = env.getRequiredProperty(&quot;spring.datasource.url&quot;) + schema;
        return DataSourceBuilder.create()
            .driverClassName(env.getRequiredProperty(&quot;spring.datasource.driverClassName&quot;))
            [...]
            .url(url)
            .build();
    }
}

<br/>
Now, just like any other data source this can be used in a spring configuration file like this:<br/>

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef = &quot;schemaSpecificEntityManagerFactory&quot;,
    transactionManagerRef = &quot;schemaSpecificTransactionManager&quot;)
public class SchemaSpecificConfig {

    @Bean(name = &quot;schemaSpecificDataSource&quot;)
    public DataSource schemaSpecificDataSource(){
        return new BuyerSchemaDataSource();
    }

    @Bean(name = &quot;schemaSpecificEntityManagerFactory&quot;)
    public LocalContainerEntityManagerFactoryBean schemaSpecificEntityManagerFactory(
        EntityManagerFactoryBuilder builder, @Qualifier(&quot;schemaSpecificDataSource&quot;) DataSource dataSource) {

        HashMap&lt;String, Object&gt; properties = new HashMap&lt;&gt;();
        properties.put(&quot;hibernate.hbm2ddl.auto&quot;, &quot;update&quot;);
        properties.put(&quot;hibernate.dialect&quot;, &quot;org.hibernate.dialect.PostgreSQLDialect&quot;);
        return builder.dataSource(dataSource).properties(properties)
            .persistenceUnit(&quot;SchemaSpecific&quot;).build();
    }

    @Bean(name = &quot;schemaSpecificTransactionManager&quot;)
    public PlatformTransactionManager schemaSpecificTransactionManager(
        @Qualifier(&quot;schemaSpecificEntityManagerFactory&quot;) EntityManagerFactory schemaSpecificEntityManagerFactory) {
        return new JpaTransactionManager(schemaSpecificEntityManagerFactory);
    }
}

<br/>
Now, the setSchema() method defined in BuyerSchemaDataSource can be called from inside API logic in controller.<br/><br/>
This looks like a bad way to solve it but I have not find anything better than this and all suggestions/edits are appreciated.

huangapple
  • 本文由 发表于 2020年8月23日 18:29:18
  • 转载请务必保留本文链接:https://go.coder-hub.com/63545896.html
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