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https://github.com/xxgreg/dart_postgresql
Dart Postgresql database library.
https://github.com/xxgreg/dart_postgresql
Last synced: about 2 months ago
JSON representation
Dart Postgresql database library.
- Host: GitHub
- URL: https://github.com/xxgreg/dart_postgresql
- Owner: xxgreg
- License: bsd-2-clause
- Created: 2013-03-01T09:42:22.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2016-10-29T21:29:43.000Z (almost 8 years ago)
- Last Synced: 2024-06-18T18:31:41.909Z (3 months ago)
- Language: Dart
- Size: 551 KB
- Stars: 84
- Watchers: 6
- Forks: 29
- Open Issues: 19
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
- awesome-dart - PostgreSQL - Dart Postgresql database library.[<img src="https://travis-ci.org/xxgreg/dart_postgresql.svg?branch=master">](https://travis-ci.org/xxgreg/dart_postgresql) (Libraries / Database)
- awesome-dart - PostgreSQL - PostgreSQL database driver. (Database)
README
# PostgreSQL database driver for Dart
[](https://travis-ci.org/xxgreg/dart_postgresql/)
## Basic usage
### Obtaining a connection
```dart
var uri = 'postgres://username:password@localhost:5432/database';
connect(uri).then((conn) {
// ...
});
```
### SSL connections
Set the sslmode to require by appending this to the connection uri. This driver only supports sslmode=require, if sslmode is ommitted the driver will always connect without using SSL.
```dart
var uri = 'postgres://username:password@localhost:5432/database?sslmode=require';
connect(uri).then((conn) {
// ...
});
```
### Querying
```dart
conn.query('select color from crayons').toList().then((rows) {
for (var row in rows) {
print(row.color); // Refer to columns by name,
print(row[0]); // Or by column index.
}
});
```
### Executing
```dart
conn.execute("update crayons set color = 'pink'").then((rowsAffected) {
print(rowsAffected);
});
```
### Query Parameters
Query parameters can be provided using a map. Strings will be escaped to prevent SQL injection vulnerabilities.
```dart
conn.query('select color from crayons where id = @id', {'id': 5})
.toList()
.then((result) { print(result); });
conn.execute('insert into crayons values (@id, @color)',
{'id': 1, 'color': 'pink'})
.then((_) { print('done.'); });
```
### Closing the connection
You must remember to call Connection.close() when you're done. This won't be
done automatically for you.
### Conversion of Postgresql datatypes.
Below is the mapping from Postgresql types to Dart types. All types which do not have an explicit mapping will be returned as a String in Postgresql's standard text format. This means that it is still possible to handle all types, as you can parse the string yourself.
```
Postgresql type Dart type
boolean bool
int2, int4, int8 int
float4, float8 double
numeric String
timestamp, timestamptz, date Datetime
json, jsonb Map/List
All other types String
```
### Mapping the results of a query to an object
```dart
class Crayon {
String color;
int length;
}
conn.query('select color, length from crayons')
.map((row) => new Crayon()
..color = row.color
..length = row.length)
.toList()
.then((List crayons) {
for (var c in crayons) {
print(c is Crayon);
print(c.color);
print(c.length);
}
});
```
Or for an immutable object:
```dart
class ImmutableCrayon {
ImmutableCrayon(this.color, this.length);
final String color;
final int length;
}
conn.query('select color, length from crayons')
.map((row) => new ImmutableCrayon(row.color, row.length))
.toList()
.then((List crayons) {
for (var c in crayons) {
print(c is ImmutableCrayon);
print(c.color);
print(c.length);
}
});
```
### Query queueing
Queries are queued and executed in the order in which they were queued.
So if you're not concerned about handling errors, you can write code like this:
```dart
conn.execute("create table crayons (color text, length int)");
conn.execute("insert into crayons values ('pink', 5)");
conn.query("select color from crayons").single.then((crayon) {
print(crayon.color); // prints 'pink'
});
```
### Query streaming
Connection.query() returns a Stream of results. You can use each row as soon as
it is received, or you can wait till they all arrive by calling Stream.toList().
### Connection pooling
In server applications, a connection pool can be used to avoid the overhead of obtaining a connection for each request.
```dart
import 'package:postgresql/pool.dart';
main() {
var uri = 'postgres://username:password@localhost:5432/database';
var pool = new Pool(uri, minConnections: 2, maxConnections: 5);
pool.messages.listen(print);
pool.start().then((_) {
print('Min connections established.');
pool.connect().then((conn) { // Obtain connection from pool
conn.query("select 'oi';")
.toList()
.then(print)
.then((_) => conn.close()) // Return connection to pool
.catchError((err) => print('Query error: $err'));
});
});
}
```
### Example program
Add postgresql to your pubspec.yaml file, and run pub install.
```
name: postgresql_example
dependencies:
postgresql: any
```
```dart
import 'package:postgresql/postgresql.dart';
void main() {
var uri = 'postgres://testdb:password@localhost:5432/testdb';
var sql = "select 'oi'";
connect(uri).then((conn) {
conn.query(sql).toList()
.then((result) {
print('result: $result');
})
.whenComplete(() {
conn.close();
});
});
}
```
## Testing
To run the unit tests you will need to create a database, and edit
'test/config.yaml' accordingly.
### Creating a database for testing
Change to the postgres user and run the administration commands.
```bash
sudo su postgres
createuser --pwprompt testdb
Enter password for new role: password
Enter it again: password
Shall the new role be a superuser? (y/n) n
Shall the new role be allowed to create databases? (y/n) n
Shall the new role be allowed to create more new roles? (y/n) n
createdb --owner testdb testdb
exit
```
Check that it worked by logging in.
```bash
psql -h localhost -U testdb -W
```
Enter "\q" to quit from the psql console.
## License
BSD
## Links
http://www.postgresql.org/docs/9.2/static/index.html
http://www.dartlang.org/