shard-crystal-db/api/0.6.0/DB/ResultSet.html
2019-08-02 12:16:24 -03:00

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<div class="main-content">
<h1 class="type-name">
<span class="kind">abstract class</span> DB::ResultSet
</h1>
<ul class="superclass-hierarchy"><li class="superclass"><a href="../DB/ResultSet.html">DB::ResultSet</a></li><li class="superclass">Reference</li><li class="superclass">Object</li></ul>
<h2>Overview</h2>
<p>The response of a query performed on a <code><a href="../DB/Database.html">Database</a></code>.</p>
<p>See <code><a href="../DB.html">DB</a></code> for a complete sample.</p>
<p>Each <code><a href="../DB/ResultSet.html#read(**types:Class)-instance-method">#read</a></code> call consumes the result and moves to the next column.
Each column must be read in order.
At any moment a <code><a href="../DB/ResultSet.html#move_next:Bool-instance-method">#move_next</a></code> can be invoked, meaning to skip the
remaining, or even all the columns, in the current row.
Also it is not mandatory to consume the whole <code><a href="../DB/ResultSet.html">ResultSet</a></code>, hence an iteration
through <code><a href="../DB/ResultSet.html#each(&block)-instance-method">#each</a></code> or <code><a href="../DB/ResultSet.html#move_next:Bool-instance-method">#move_next</a></code> can be stopped.</p>
<p><strong>Note:</strong> depending on how the <code><a href="../DB/ResultSet.html">ResultSet</a></code> was obtained it might be mandatory an
explicit call to <code>#close</code>. Check <code><a href="../DB/QueryMethods.html#query(query,*args)-instance-method">QueryMethods#query</a></code>.</p>
<h3>Note to implementors</h3>
<ol><li>Override <code><a href="../DB/ResultSet.html#move_next:Bool-instance-method">#move_next</a></code> to move to the next row.</li><li>Override <code><a href="../DB/ResultSet.html#read(**types:Class)-instance-method">#read</a></code> returning the next value in the row.</li><li>(Optional) Override <code><a href="../DB/ResultSet.html#read(type:DB::Mappable.class)-instance-method">#read(t)</a></code> for some types <code>t</code> for which custom logic other than a simple cast is needed.</li><li>Override <code><a href="../DB/ResultSet.html#column_count:Int32-instance-method">#column_count</a></code>, <code><a href="../DB/ResultSet.html#column_name(index:Int32):String-instance-method">#column_name</a></code>.</li></ol>
<h2>Included Modules</h2>
<ul class="other-types-list">
<li class="other-type"><a href="../DB/Disposable.html">DB::Disposable</a></li>
</ul>
<h2>Defined in:</h2>
<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L22" target="_blank">
db/result_set.cr
</a>
<br/>
<h2>Constructors</h2>
<ul class="list-summary">
<li class="entry-summary">
<a href="#new(statement:DB::Statement)-class-method" class="signature"><strong>.new</strong>(statement : DB::Statement)</a>
</li>
</ul>
<h2>Instance Method Summary</h2>
<ul class="list-summary">
<li class="entry-summary">
<a href="#column_count:Int32-instance-method" class="signature"><strong>#column_count</strong> : Int32</a>
<div class="summary"><p>Returns the number of columns in the result</p></div>
</li>
<li class="entry-summary">
<a href="#column_name(index:Int32):String-instance-method" class="signature"><strong>#column_name</strong>(index : Int32) : String</a>
<div class="summary"><p>Returns the name of the column in <code>index</code> 0-based position.</p></div>
</li>
<li class="entry-summary">
<a href="#column_names-instance-method" class="signature"><strong>#column_names</strong></a>
<div class="summary"><p>Returns the name of the columns.</p></div>
</li>
<li class="entry-summary">
<a href="#each(&block)-instance-method" class="signature"><strong>#each</strong>(&block)</a>
<div class="summary"><p>Iterates over all the rows</p></div>
</li>
<li class="entry-summary">
<a href="#each_column(&block)-instance-method" class="signature"><strong>#each_column</strong>(&block)</a>
<div class="summary"><p>Iterates over all the columns</p></div>
</li>
<li class="entry-summary">
<a href="#move_next:Bool-instance-method" class="signature"><strong>#move_next</strong> : Bool</a>
<div class="summary"><p>Move the next row in the result.</p></div>
</li>
<li class="entry-summary">
<a href="#read(type:DB::Mappable.class)-instance-method" class="signature"><strong>#read</strong>(type : <span class="t">DB</span><span class="t">::</span><span class="t">Mappable</span>.<span class="k">class</span>)</a>
<div class="summary"><p>Reads the next columns and maps them to a class</p></div>
</li>
<li class="entry-summary">
<a href="#read(type:T.class):TforallT-instance-method" class="signature"><strong>#read</strong>(type : <span class="t">T</span>.<span class="k">class</span>) : T forall T</a>
<div class="summary"><p>Reads the next column value as a <strong>type</strong></p></div>
</li>
<li class="entry-summary">
<a href="#read(**types:Class)-instance-method" class="signature"><strong>#read</strong>(**types : Class)</a>
<div class="summary"><p>Reads the next columns and returns a named tuple of the values.</p></div>
</li>
<li class="entry-summary">
<a href="#read-instance-method" class="signature"><strong>#read</strong></a>
<div class="summary"><p>Reads the next column value</p></div>
</li>
<li class="entry-summary">
<a href="#read(*types:Class)-instance-method" class="signature"><strong>#read</strong>(*types : Class)</a>
<div class="summary"><p>Reads the next columns and returns a tuple of the values.</p></div>
</li>
</ul>
<div class="methods-inherited">
<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?-instance-method" class="tooltip">
<span>closed?</span>
closed?</a>
</div>
<h2>Constructor Detail</h2>
<div class="entry-detail" id="new(statement:DB::Statement)-class-method">
<div class="signature">
def self.<strong>new</strong>(statement : <a href="../DB/Statement.html">DB::Statement</a>)
<a class="method-permalink" href="#new(statement:DB::Statement)-class-method">#</a>
</div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L28" target="_blank">View source</a>]
</div>
</div>
<h2>Instance Method Detail</h2>
<div class="entry-detail" id="column_count:Int32-instance-method">
<div class="signature">
abstract
def <strong>column_count</strong> : Int32
<a class="method-permalink" href="#column_count:Int32-instance-method">#</a>
</div>
<div class="doc"><p>Returns the number of columns in the result</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L59" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="column_name(index:Int32):String-instance-method">
<div class="signature">
abstract
def <strong>column_name</strong>(index : Int32) : String
<a class="method-permalink" href="#column_name(index:Int32):String-instance-method">#</a>
</div>
<div class="doc"><p>Returns the name of the column in <code>index</code> 0-based position.</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L62" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="column_names-instance-method">
<div class="signature">
def <strong>column_names</strong>
<a class="method-permalink" href="#column_names-instance-method">#</a>
</div>
<div class="doc"><p>Returns the name of the columns.</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L65" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="each(&amp;block)-instance-method">
<div class="signature">
def <strong>each</strong>(&block)
<a class="method-permalink" href="#each(&block)-instance-method">#</a>
</div>
<div class="doc"><p>Iterates over all the rows</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L38" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="each_column(&amp;block)-instance-method">
<div class="signature">
def <strong>each_column</strong>(&block)
<a class="method-permalink" href="#each_column(&block)-instance-method">#</a>
</div>
<div class="doc"><p>Iterates over all the columns</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L45" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="move_next:Bool-instance-method">
<div class="signature">
abstract
def <strong>move_next</strong> : Bool
<a class="method-permalink" href="#move_next:Bool-instance-method">#</a>
</div>
<div class="doc"><p>Move the next row in the result.
Return <code>false</code> if no more rows are available.
See <code><a href="../DB/ResultSet.html#each(&block)-instance-method">#each</a></code></p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L54" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="read(type:DB::Mappable.class)-instance-method">
<div class="signature">
def <strong>read</strong>(type : <span class="t">DB</span><span class="t">::</span><span class="t">Mappable</span>.<span class="k">class</span>)
<a class="method-permalink" href="#read(type:DB::Mappable.class)-instance-method">#</a>
</div>
<div class="doc"><p>Reads the next columns and maps them to a class</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L73" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="read(type:T.class):TforallT-instance-method">
<div class="signature">
def <strong>read</strong>(type : <span class="t">T</span>.<span class="k">class</span>) : T forall T
<a class="method-permalink" href="#read(type:T.class):TforallT-instance-method">#</a>
</div>
<div class="doc"><p>Reads the next column value as a <strong>type</strong></p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L78" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="read(**types:Class)-instance-method">
<div class="signature">
def <strong>read</strong>(**types : Class)
<a class="method-permalink" href="#read(**types:Class)-instance-method">#</a>
</div>
<div class="doc"><p>Reads the next columns and returns a named tuple of the values.</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L93" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="read-instance-method">
<div class="signature">
abstract
def <strong>read</strong>
<a class="method-permalink" href="#read-instance-method">#</a>
</div>
<div class="doc"><p>Reads the next column value</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L70" target="_blank">View source</a>]
</div>
</div>
<div class="entry-detail" id="read(*types:Class)-instance-method">
<div class="signature">
def <strong>read</strong>(*types : Class)
<a class="method-permalink" href="#read(*types:Class)-instance-method">#</a>
</div>
<div class="doc"><p>Reads the next columns and returns a tuple of the values.</p></div>
<br/>
<div>
[<a href="https://github.com/crystal-lang/crystal-db/blob/dcd0af5ce81b5a43305e02846106633373f65004/src/db/result_set.cr#L88" target="_blank">View source</a>]
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