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// constructed for each platform.
join(await getDatabasesPath(), 'doggie_database.db'),
// When the database is first created, create a table to store dogs.
onCreate: (db, version) {
// Run the CREATE TABLE statement on the database.
return db.execute(
'CREATE TABLE dogs(id INTEGER PRIMARY KEY, name TEXT, age INTEGER)',
);
},
// Set the version. This executes the onCreate function and provides a
// path to perform database upgrades and downgrades.
version: 1,
);<code_end>
<topic_end>
<topic_start>
5. Insert a Dog into the database
Now that you have a database with a table suitable for storing information
about various dogs, it’s time to read and write data.First, insert a Dog into the dogs table. This involves two steps:
<code_start>class Dog {
final int id;
final String name;
final int age;
Dog({
required this.id,
required this.name,
required this.age,
});
// Convert a Dog into a Map. The keys must correspond to the names of the
// columns in the database.
Map<String, Object?> toMap() {
return {
'id': id,
'name': name,
'age': age,
};
}
// Implement toString to make it easier to see information about
// each dog when using the print statement.
@override
String toString() {
return 'Dog{id: $id, name: $name, age: $age}';
}
}<code_end>
<code_start>// Define a function that inserts dogs into the database
Future<void> insertDog(Dog dog) async {
// Get a reference to the database.
final db = await database;
// Insert the Dog into the correct table. You might also specify the
// `conflictAlgorithm` to use in case the same dog is inserted twice.
//
// In this case, replace any previous data.
await db.insert(
'dogs',
dog.toMap(),
conflictAlgorithm: ConflictAlgorithm.replace,
);
}<code_end>
<code_start>// Create a Dog and add it to the dogs table
var fido = Dog(
id: 0,
name: 'Fido',
age: 35,
);
await insertDog(fido);<code_end>
<topic_end>
<topic_start>
6. Retrieve the list of Dogs
Now that a Dog is stored in the database, query the database
for a specific dog or a list of all dogs. This involves two steps:
<code_start>// A method that retrieves all the dogs from the dogs table.
Future<List<Dog>> dogs() async {
// Get a reference to the database.
final db = await database;
// Query the table for all the dogs.
final List<Map<String, Object?>> dogMaps = await db.query('dogs');
// Convert the list of each dog's fields into a list of `Dog` objects.
return [
for (final {
'id': id as int,
'name': name as String,
'age': age as int,
} in dogMaps)
Dog(id: id, name: name, age: age),
];
}<code_end>
<code_start>// Now, use the method above to retrieve all the dogs.
print(await dogs()); // Prints a list that include Fido.<code_end>
<topic_end>
<topic_start>
7. Update a Dog in the database
After inserting information into the database,
you might want to update that information at a later time.
You can do this by using the update()
method from the sqflite library.This involves two steps:
<code_start>Future<void> updateDog(Dog dog) async {
// Get a reference to the database.
final db = await database;
// Update the given Dog.
await db.update(
'dogs',