InjectQ

A Spring Boot extension allowing for injecting the SQL query strings from the files on the classpath into the Spring-managed components.

Dependency

This project is distributed via JitPack. Register a JitPack repository at your pom.xml:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

And add the following dependency:

<dependency>
    <groupId>com.github.jolice</groupId>
    <artifactId>injectq</artifactId>
    <version>1.0</version>
</dependency>

Injecting a query

Enabling the extension

First of all, enable the InjectQuery by placing the @EnableInjectQuery annotation at some configuration or the main class of your application:

@EnableInjectQuery
@Configuration
public class MyApplicationConfiguration {

This step is mandatory for importing the extension components into your application.

Basic injection

The query injection is carried out via @SqlQuery annotation. To inject a query, place @SqlQuery annotation at one of the supported injection points: field, method or constructor and specify the name of the file storing your query without the extension:

@SqlQuery("all-employees")
private String allEmployees;

The query string will be read from all-employees.sql file on your classpath, in most cases (for example, when using Maven) from the resources directory.

Constructor and method injection

You are free to inject your queries the same way as supplying the regular dependencies, including the constructor and setter options:

public class EmployeeRepository {

    private final String getAllEmployeesQuery;

    public EmployeeRepository(@SqlQuery("all-employees") String getAllEmployeesQuery) {
        this.getAllEmployeesQuery = getAllEmployeesQuery;
    }
}

Setter injection is pretty straightforward as well:

@SqlQuery("all-employees")
public void setAllEmployeesQuery(String allEmployeesQuery) {
    this.allEmployeesQuery = allEmployeesQuery;
}

The preferred injection option

There's no flawless and unequivocally preferable injection approach, each has its proc and cons.

• The field injection seems handy enough at first glance, but has a disadvantage of complicating the unit testing, namely setting the private field value outside of the Spring context.
• The method injection implies the mutability and exposes many unwanted methods serving only for the DI container.
• The constructor injection may seem as the best option among others, however, the drawback is that injecting many queries will lead to the bloat constructors.

Configuration

The extension may be configured via the @EnableInjectQuery annotation. Currently supported configuration options are listed below.

Path

To set a default root path for all queries, use the path option:

@EnableInjectQuery(path = "queries")

The query files will be always read under the queries directory, e.g:

@SqlQuery("all-employees")
private String getAllEmployeesQuery; 

The query will be read from the resource located at queries/all-employees.sql.

Extension

For some reason, you may also want to change the default script file extension :

@EnableInjectQuery(extension = "txt")

Thus, the query for the following injection point:

@SqlQuery("all-employees")
private String getAllEmployeesQuery; 

Will be read from the file located at all-employees.txt.