shard-crystal-db/api/0.4.2/DB/Connection.html

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<div id="main-content">
<h1 class="type-name">
<span class="kind">abstract class</span> DB::Connection
</h1>
<ul class="superclass-hierarchy"><li class="superclass"><a href="../DB/Connection.html">DB::Connection</a></li><li class="superclass">Reference</li><li class="superclass">Object</li></ul>
<h2>Overview</h2>
<p>Database driver implementors must subclass <code><a href="../DB/Connection.html">Connection</a></code>.</p>
<p>Represents one active connection to a database.</p>
<p>Users should never instantiate a <code><a href="../DB/Connection.html">Connection</a></code> manually. Use <code><a href="../DB.html#open%28uri%3AURI%7CString%29-class-method">DB#open</a></code> or <code>Database#connection</code>.</p>
<p>Refer to <code><a href="../DB/QueryMethods.html">QueryMethods</a></code> for documentation about querying the database through this connection.</p>
<h3>Note to implementors</h3>
<p>The connection must be initialized in <code>#initialize</code> and closed in <code>#do_close</code>.</p>
<p>Override <code>#build_prepared_statement</code> method in order to return a prepared <code><a href="../DB/Statement.html">Statement</a></code> to allow querying.
Override <code>#build_unprepared_statement</code> method in order to return a unprepared <code><a href="../DB/Statement.html">Statement</a></code> to allow querying.
See also <code><a href="../DB/Statement.html">Statement</a></code> to define how the statements are executed.</p>
<p>If at any give moment the connection is lost a DB::ConnectionLost should be raised. This will
allow the connection pool to try to reconnect or use another connection if available.</p>
<h2>Included Modules</h2>
<ul class="other-types-list">
<li class="other-type"><a href="../DB/BeginTransaction.html">DB::BeginTransaction</a></li>
<li class="other-type"><a href="../DB/Disposable.html">DB::Disposable</a></li>
<li class="other-type"><a href="../DB/SessionMethods.html">DB::SessionMethods</a>(<a href="../DB/Connection.html">DB::Connection</a>, <a href="../DB/Statement.html">DB::Statement</a>)</li>
</ul>
<h2>Defined in:</h2>
<a href="https://github.com/crystal-lang/crystal-db/blob/28c6f3b715f0c82d2a37106fd5a55882a238cc1f/src/db/connection.cr#L21" target="_blank">db/connection.cr</a>
<br/>
<h2>Class Method Summary</h2>
<ul class="list-summary">
<li class="entry-summary">
<a href="#new%28context%3AConnectionContext%29-class-method" class="signature"><strong>.new</strong>(context : ConnectionContext)</a>
</li>
</ul>
<h2>Instance Method Summary</h2>
<ul class="list-summary">
<li class="entry-summary">
<a href="#begin_transaction-instance-method" class="signature"><strong>#begin_transaction</strong></a>
</li>
<li class="entry-summary">
<a href="#prepared_statements%3F%3ABool-instance-method" class="signature"><strong>#prepared_statements?</strong> : Bool</a>
</li>
<li class="entry-summary">
<a href="#release-instance-method" class="signature"><strong>#release</strong></a>
<div class="summary"><p>return this connection to the pool managed by the database.</p></div>
</li>
</ul>
<div class="methods-inherited">
<h3>Instance methods inherited from module <code><a href="../DB/BeginTransaction.html">DB::BeginTransaction</a></code></h3>
<a href="../DB/BeginTransaction.html#begin_transaction%3ATransaction-instance-method" class="tooltip">
<span>begin_transaction : Transaction</span>
begin_transaction</a>,
<a href="../DB/BeginTransaction.html#transaction%28%26block%29-instance-method" class="tooltip">
<span>transaction(&block)</span>
transaction</a>
<h3>Instance methods inherited from module <code><a href="../DB/SessionMethods.html">DB::SessionMethods</a>(<a href="../DB/Connection.html">DB::Connection</a>, <a href="../DB/Statement.html">DB::Statement</a>)</code></h3>
<a href="../DB/SessionMethods.html#build%28query%29%3AStmt-instance-method" class="tooltip">
<span>build(query) : Stmt</span>
build</a>,
<a href="../DB/SessionMethods.html#build_unprepared_statement%28query%29%3AStmt-instance-method" class="tooltip">
<span>build_unprepared_statement(query) : Stmt</span>
build_unprepared_statement</a>,
<a href="../DB/SessionMethods.html#fetch_or_build_prepared_statement%28query%29%3AStmt-instance-method" class="tooltip">
<span>fetch_or_build_prepared_statement(query) : Stmt</span>
fetch_or_build_prepared_statement</a>,
<a href="../DB/SessionMethods.html#prepared%28query%29-instance-method" class="tooltip">
<span>prepared(query)<br/>prepared</span>
prepared</a>,
<a href="../DB/SessionMethods.html#prepared_statements%3F%3ABool-instance-method" class="tooltip">
<span>prepared_statements? : Bool</span>
prepared_statements?</a>,
<a href="../DB/SessionMethods.html#unprepared%28query%29-instance-method" class="tooltip">
<span>unprepared(query)<br/>unprepared</span>
unprepared</a>
<h3>Instance methods inherited from module <code><a href="../DB/QueryMethods.html">DB::QueryMethods</a></code></h3>
<a href="../DB/QueryMethods.html#exec%28query%2C%2Aargs%29-instance-method" class="tooltip">
<span>exec(query, *args)</span>
exec</a>,
<a href="../DB/QueryMethods.html#query%28query%2C%2Aargs%29-instance-method" class="tooltip">
<span>query(query, *args)<br/>query(query, *args, &block)</span>
query</a>,
<a href="../DB/QueryMethods.html#query_all%28query%2C%2Aargs%2C%26block%3AResultSet-%3EU%29%3AArray%28U%29forallU-instance-method" class="tooltip">
<span>query_all(query, *args, &block : ResultSet -> U) : Array(U) forall U<br/>query_all(query, *args, as types : Tuple)<br/>query_all(query, *args, as type : Class)</span>
query_all</a>,
<a href="../DB/QueryMethods.html#query_each%28query%2C%2Aargs%2C%26block%29-instance-method" class="tooltip">
<span>query_each(query, *args, &block)</span>
query_each</a>,
<a href="../DB/QueryMethods.html#query_one%28query%2C%2Aargs%2C%26block%3AResultSet-%3EU%29%3AUforallU-instance-method" class="tooltip">
<span>query_one(query, *args, &block : ResultSet -> U) : U forall U<br/>query_one(query, *args, as types : Tuple)<br/>query_one(query, *args, as type : Class)</span>
query_one</a>,
<a href="../DB/QueryMethods.html#query_one%3F%28query%2C%2Aargs%2C%26block%3AResultSet-%3EU%29%3AU%3FforallU-instance-method" class="tooltip">
<span>query_one?(query, *args, &block : ResultSet -> U) : U? forall U<br/>query_one?(query, *args, as types : Tuple)<br/>query_one?(query, *args, as type : Class)</span>
query_one?</a>,
<a href="../DB/QueryMethods.html#scalar%28query%2C%2Aargs%29-instance-method" class="tooltip">
<span>scalar(query, *args)</span>
scalar</a>
<h3>Instance methods inherited from module <code><a href="../DB/Disposable.html">DB::Disposable</a></code></h3>
<a href="../DB/Disposable.html#close-instance-method" class="tooltip">
<span>close</span>
close</a>,
<a href="../DB/Disposable.html#closed%3F-instance-method" class="tooltip">
<span>closed?</span>
closed?</a>
</div>
<h2>Class Method Detail</h2>
<div class="entry-detail" id="new&#40;context:ConnectionContext&#41;-class-method">
<div class="signature">
def self.<strong>new</strong>(context : <a href="../DB/ConnectionContext.html">ConnectionContext</a>)
<a class="method-permalink" href="#new%28context%3AConnectionContext%29-class-method">#</a>
</div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/28c6f3b715f0c82d2a37106fd5a55882a238cc1f/src/db/connection.cr#L34" target="_blank">View source</a>]
</div>
</div>
<h2>Instance Method Detail</h2>
<div class="entry-detail" id="begin_transaction-instance-method">
<div class="signature">
def <strong>begin_transaction</strong>
<a class="method-permalink" href="#begin_transaction-instance-method">#</a>
</div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/28c6f3b715f0c82d2a37106fd5a55882a238cc1f/src/db/connection.cr#L49" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="prepared_statements?:Bool-instance-method">
<div class="signature">
def <strong>prepared_statements?</strong> : Bool
<a class="method-permalink" href="#prepared_statements%3F%3ABool-instance-method">#</a>
</div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/28c6f3b715f0c82d2a37106fd5a55882a238cc1f/src/db/connection.cr#L30" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="release-instance-method">
<div class="signature">
def <strong>release</strong>
<a class="method-permalink" href="#release-instance-method">#</a>
</div>
<div class="doc"><p>return this connection to the pool
managed by the database. Should be used
only if the connection was obtained by <code><a href="../DB/Database.html#checkout-instance-method">Database#checkout</a></code>.</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/28c6f3b715f0c82d2a37106fd5a55882a238cc1f/src/db/connection.cr#L77" target="_blank">View source</a>]
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