JDBC

Utilities for working with the raw JDBC api.

Includes

• A template processor for making prepared statements.
• Utilities for reading data from ResultSets

NOTE: Template processors are currently a preview feature, and as such releases of this library are tied to a specific release of Java.

Expect to have to upgrade.

Dependency Information

Maven

<dependency>
    <groupId>dev.mccue</groupId>
    <artifactId>jdbc</artifactId>
    <version>0.0.1-alpha3</version>
</dependency>

Gradle

dependencies {
    implementation("dev.mccue:jdbc:0.0.1-alpha3")
}

Usage

These examples use sqlite.

Select rows by id

Any variables injected into the template will be replaced with ?s in the SQL and will be set with .setObject on the returned PreparedStatement.

import dev.mccue.jdbc.StatementPreparer;

void main() throws Exception {
    var db = new SQLiteDataSource();
    db.setUrl("jdbc:sqlite:test.db");

    var id = 1;
    try (var conn = db.getConnection()) {
        try (var stmt = StatementPreparer.of(conn)."""
                SELECT *
                FROM widget
                WHERE id = \{id}
                """) {
            var rs = stmt.executeQuery();
        }
    }
}

Select rows by ids

List parameters are automatically expanded into (?, ?, ?) with one question mark for each element in the list.

import dev.mccue.jdbc.StatementPreparer;

void main() throws Exception {
    var db = new SQLiteDataSource();
    db.setUrl("jdbc:sqlite:test.db");

    var ids = List.of(1, 2, 3);
    try (var conn = db.getConnection()) {
        try (var stmt = StatementPreparer.of(conn)."""
                SELECT *
                FROM widget
                WHERE id IN \{ids}
                """) {
            var rs = stmt.executeQuery();
        }
    }
}

Inject parameters with custom logic

To inject a parameter that needs to be set with something other than setObject, you can make an instance of SettableParameter.

import dev.mccue.jdbc.SettableParameter;
import dev.mccue.jdbc.StatementPreparer;

void main() throws Exception {
    var db = new SQLiteDataSource();
    db.setUrl("jdbc:sqlite:test.db");

    var name = "bob";
    try (var conn = db.getConnection()) {
        try (var stmt = StatementPreparer.of(conn)."""
                SELECT *
                FROM widget
                WHERE name = \{SettableParameter.ofNString(name)}
                """){
            var rs = stmt.executeQuery();
        }
    }
}

Read nullable primitive types

ResultSets includes helpers for reading potentially null primitive types from a ResultSet

import dev.mccue.jdbc.ResultSets;

void main() throws Exception {
    var db = new SQLiteDataSource();
    db.setUrl("jdbc:sqlite:test.db");

    var name = "bob";
    try (var conn = db.getConnection()) {
        try (var stmt = conn.prepareStatement("""
                SELECT number
                FROM widget
                LIMIT 1
                """)) {
            var rs = stmt.executeQuery();

            // Methods exist for all primitives except char 
            // (which doesn't have a method on ResultSet)
            var number = ResultSets.getIntegerNullable(rs, "number");
        }
    }
}

Read non-null primitive types

If you want to read a column that is primitive, but you assume is not null, there are helpers which will throw a SQLException early if that assumption is violated.

import dev.mccue.jdbc.ResultSets;

void main() throws Exception {
    var db = new SQLiteDataSource();
    db.setUrl("jdbc:sqlite:test.db");

    var name = "bob";
    try (var conn = db.getConnection()) {
        try (var stmt = conn.prepareStatement("""
                SELECT number
                FROM widget
                LIMIT 1
                """)) {
            var rs = stmt.executeQuery();

            // Methods exist for all primitives except char 
            // (which doesn't have a method on ResultSet)
            var number = ResultSets.getIntegerNotNull(rs, "number");
        }
    }
}