dpq 0.5.9
A postgresql (libpq, pq) library aiming to be simple to use
To use this package, run the following command in your project's root directory:
Manual usage
Put the following dependency into your project's dependences section:
dpq - A D PostgreSQL library
dpq wraps the libpq library and aims to provide a simple and modern way to access PostgreSQL in the D programming language.
Current features:
- Opening a connection using a connection string
- Queries
- Fetching the results of queries in binary format
- Looping through the said results
- Exceptions on query errors
- Automatic (de-)serialisation of structs/classes
- Automatic schema creation from struct/classes (includes PKs, FKs, indexes)
- Reading and writing to array fields (up to 6-dimensions, limited by PostgreSQL)
- Basic asynchronous query support with Query.runAsync()
- Prepared statements
Planned features
- Connection pooling (maybe)
- Date/Time types support
- Extensive documentantion
Documentation
Documentation is in the code itself, though not complete
Some notes:
- If a wrong type is specified while fetching a column, the results are undefined. Most likely just garbage
- Using QueryBuilder, when specifying columns, make sure they are not reserverd SQL keywords, they will not be escaped automatically (wrap keywords in
" "
)
Licence
MIT, read LICENSE.txt
Example
import std.stdio;
import dpq.connection;
import dpq.query;
import dpq.attributes;
import dpq.result;
struct UserData
{
string firstName;
string lastName;
}
// A relation's name can be specified with the @relation attribute
@relation("users")
struct User
{
// serial is 4B in size, use serial8 with longs (@serial == @type("SERIAL"))
@serial @PK int id;
// @uniqueIndex will create an unique index, @index non-unique
@uniqueIndex string username;
@index int posts;
// Struct inside structs can be used, they will be created as a type
UserData userData;
// ubyte[] will get store as BYTEA
// Attribute/column names can be specified using the @attribute UDA (@attr is an alias for it)
@attr("passwordHash") ubyte[] password;
// Private properties will be ignored, same for @ignore
private int _secret;
// A getter-setter pair will get (de-)serialised too.
@property int secret()
{
return _secret;
}
@property void secret(int newSecret)
{
_secret = newSecret;
}
}
struct Post
{
@serial @PK int id;
// @FK will automatically find the referenced table's PK
@FK!User int userId;
string title;
string content;
}
void main()
{
// Establish a connection, will throw if connecting fails or connection string cannot be parsed
auto conn = Connection("host=anubis.ad.nuclei.co dbname=testdb user=testuser password='VerySecureTestPassword'");
// One-line query execution, the same could be done with Connection.exec(string command)
Query("CREATE TABLE IF NOT EXISTS test (id SERIAL, txt TEXT)").run();
auto q = Query("INSERT INTO test (txt) VALUES ('Some text')");
// A query can be run twice, if you wish to do so, inserting two rows in this case
q.run();
q.run();
// Last connection will be used if none is specified as the first param to Query()
q = Query("SELECT id, txt FROM test WHERE id = $1 OR id = $2");
// Params could also be added with the << operator
// q << 4 << 1;
Result r = q.run(4, 1);
writefln("Our query returned %d rows, each with %d columns", r.rows, r.columns);
writefln("Additionaly, the query took %d ms to complete.", r.time.msecs);
// Looping with foreach works as expected
foreach (row; r)
// Make sure you don't specify the incorrect type to as(),
// the results are undefined, but mosty likely
// you will either get garbage or a RangeError
writeln("row[\"txt\"] is: ", row["txt"].as!string);
// This will create a schema out of the two specified types
// Indexes, primary keys, and foreign keys will also be created
// as specified by the UDAs on struct/class members
conn.ensureSchema!(User, Post);
User newUser;
newUser.username = "foobar123999";
newUser.userData.firstName = "Foo";
newUser.userData.lastName = "Bar";
// This will insert an the given user.
conn.insert(newUser);
// This will return a Nullable!User, searched for by the User's primary key
// if no rows are returned, a Nullable null value will be returned
auto user = conn.findOne!User(1);
writeln("User: ", user);
// Similar to above, but we specify what attribute we are filtering by
auto user2 = conn.findOneBy!User("username", "foobar123");
writeln("User 2:", user2);
// The most powerful version of findOne -- allows you to specify a custom filter
// Parameters can be given as with normal queries, beginning with $1.
auto user3 = conn.findOne!User("id > $1 AND username LIKE 'a%'", 1);
writeln("User 3: ", user3);
// This will return an array of users with more than 100 posts,
// if no rows are returned by the query, the array will have a length of 0
User[] users = conn.find!User("posts > $1", 100);
writeln("Users: ", users);
// Connection does not have to be closed, the destructor will take care of that,
// but it can still manually be closed using conn.close()
}
- Registered by Irenej Marc
- 0.5.9 released 8 years ago
- IrenejMarc/dpq
- MIT
- Copyright © 2016, Irenej Marc
- Authors:
- Dependencies:
- derelict-pq
- Versions:
-
0.11.6 2022-Jun-04 0.11.5 2021-Jun-25 0.11.4 2020-Sep-30 0.11.3 2020-Sep-05 0.11.2 2020-Aug-25 - Download Stats:
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7 downloads today
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162 downloads this month
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4080 downloads total
-
- Score:
- 3.2
- Short URL:
- dpq.dub.pm