Datasets:
Ekhlass
/
flutter_docs

Dataset card Data Studio Files
xet
Community
1
text
stringlengths
1
372
// `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',
dog.toMap(),
// ensure that the dog has a matching id.
where: 'id = ?',
// pass the dog's id as a whereArg to prevent SQL injection.
whereArgs: [dog.id],
);
}
<code_end>
<code_start>
// update fido's age and save it to the database.
fido = dog(
id: fido.id,
name: fido.name,
age: fido.age + 7,
);
await updateDog(fido);
// print the updated results.
print(await dogs()); // prints fido with age 42.
<code_end>
warning warning
always use whereArgs to pass arguments to a where statement.
this helps safeguard against SQL injection attacks.
do not use string interpolation, such as where: "id = ${dog.id}"!
<topic_end>
<topic_start>
8. delete a dog from the database
in addition to inserting and updating information about dogs,
you can also remove dogs from the database. to delete data,
use the delete() method from the sqflite library.
in this section, create a function that takes an id and deletes the dog with
a matching id from the database. to make this work, you must provide a where
clause to limit the records being deleted.
<code_start>
future<void> deleteDog(int id) async {
// get a reference to the database.
final db = await database;
// remove the dog from the database.
await db.delete(
'dogs',