A damn simple JDBC wrapper. Y'know. For databases.
- Java SE 8 or above
- Scala 2.12.x
First, specify Jdub as a dependency:
<dependencies>
<dependency>
<groupId>com.simple</groupId>
<artifactId>jdub_${scala.major.version}</artifactId>
<version>${jdub.version}</version>
</dependency>
</dependencies>(Don't forget to include your JDBC driver!)
Second, connect to a database:
val db = Database.connect("jdbc:postgresql://localhost/wait_what", "myaccount", "mypassword")Third, run some queries:
// Query returning an optional single result.
case class GetAge(name: String) extends FlatSingleRowQuery[Int] {
val sql = trim("""
SELECT age /* Use C-style comments in trimmed queries */
FROM people
WHERE name = ?
""")
val values = Seq(name)
def flatMap(row: Row) = {
// Returns Option[Int]
row.int(0) // 0 gets the first column
}
}
val age = db(GetAge("Old Guy")).getOrElse(-1) // 402// Query returning a Person object for each row.
case object GetPeople extends CollectionQuery[Seq, Person] {
val sql = trim("""
SELECT name, email, age
FROM people
""")
val values = Seq()
def map(row: Row) = {
val name = row.string("name").get
val email = row.string("email").getOrElse("")
val age = row.int("age").getOrElse(0)
Person(name, email, age)
}
}
val person = db(GetPeople).head // Person(Coda Hale,chale@example.com,29)You can also use the sql string interpolator:
class PersonQueries(val database: Database) {
// Query returning an optional single result.
def getAge(name: String): Option[Int] = database {
sql"""
SELECT age
FROM people
WHERE name = ${name}
""".map { row =>
row.int("age")
}
}.headOption
}
val personQueries = new PersonQueries(database)
val age = personQueries.getAge("Old Guy").getOrElse(-1) // 402object PersonQueries {
def mapper(row: Row): String = {
Person(
name = row.string("name").get
email = row.string("email").getOrElse("")
age = row.int("age").getOrElse(0)
)
}
}
class PersonQueries(val database: Database) {
// Query returning Person objects for each row.
def getPeople(): Seq[Person] = database {
sql"""
SELECT name, email, age
FROM people
""".map(PersonQueries.mapper)
}
}
val personQueries = new PersonQueries(database)
val people = personQueries.getPeople.head // Person(Coda Hale,chale@example.com,29)Fourth, execute some statements:
case class UpdateEmail(name: String, newEmail: String) extends Statement {
val sql = trim("""
UPDATE people
SET email = ?
WHERE name = ?
""")
val values = Seq(newEmail, name)
}
// Execute the statement.
db.execute(UpdateEmail("Old Guy", "oldguy@example.com"))
// Or return the number of rows updated.
val count = db.update(UpdateEmail("Old Guy", "oldguy@example.com")) // 1You can also use the sql string interpolator:
object PersonQueries {
def mapper(row: Row): String = {
Person(
name = row.string("name").get
email = row.string("email").getOrElse("")
age = row.int("age").getOrElse(0)
)
}
}
class PersonQueries(val database: Database) {
// Update a Person's email
def updateEmail(name: String, newEmail: String): Option[Person] = database {
sql"""
UPDATE people
SET email = ${newEmail}
WHERE name = ${name}
RETURNING people.*
""".map(PersonQueries.mapper)
}.headOption
}
val personQueries = new PersonQueries(database)
val updatedPerson = personQueries.updateEmail("Old Guy", "oldguy@example.com")Fifth, read up on all the details in the Jdub tour.
Copyright (c) 2011-2012 Coda Hale Copyright (c) 2012-2017 Simple Finance Technology Corp. All rights reserved.
Published under The MIT License, see LICENSE.md