2016-01-28 23:31:35 +00:00
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module DB
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2016-01-31 22:40:02 +00:00
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# The response of a query performed on a `Database`.
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#
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# See `DB` for a complete sample.
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#
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# Each `#read` call consumes the result and moves to the next column.
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2016-02-19 21:42:30 +00:00
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# Each column must be read in order.
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# At any moment a `#move_next` can be invoked, meaning to skip the
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# remaining, or even all the columns, in the current row.
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# Also it is not mandatory to consume the whole `ResultSet`, hence an iteration
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# through `#each` or `#move_next` can be stopped.
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#
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# **Note:** depending on how the `ResultSet` was obtained it might be mandatory an
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# explicit call to `#close`. Check `QueryMethods#query`.
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2016-01-31 22:40:02 +00:00
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#
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# ### Note to implementors
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#
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# 1. Override `#move_next` to move to the next row.
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2016-06-28 17:02:08 +00:00
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# 2. Override `#read` returning the next value in the row.
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# 3. (Optional) Override `#read(t)` for some types `t` for which custom logic other than a simple cast is needed.
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2016-01-31 22:40:02 +00:00
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# 4. Override `#column_count`, `#column_name`.
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2016-01-28 23:31:35 +00:00
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abstract class ResultSet
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2016-02-03 20:10:03 +00:00
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include Disposable
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2016-02-03 21:46:37 +00:00
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# :nodoc:
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2016-01-28 23:31:35 +00:00
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getter statement
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2016-02-04 00:51:32 +00:00
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def initialize(@statement : DB::Statement)
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2016-01-28 23:31:35 +00:00
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end
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2016-02-03 22:30:51 +00:00
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protected def do_close
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2016-02-04 00:28:53 +00:00
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statement.release_connection
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2016-02-03 22:30:51 +00:00
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end
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2016-02-02 00:55:30 +00:00
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# TODO add_next_result_set : Bool
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2016-01-31 22:40:02 +00:00
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# Iterates over all the rows
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2016-01-28 23:51:03 +00:00
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def each
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2016-01-29 19:13:01 +00:00
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while move_next
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2016-01-28 23:51:03 +00:00
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yield
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end
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end
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2016-03-28 22:29:15 +00:00
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# Iterates over all the columns
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def each_column
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column_count.times do |x|
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yield column_name(x), column_type(x)
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end
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end
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2016-01-31 22:40:02 +00:00
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# Move the next row in the result.
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# Return `false` if no more rows are available.
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# See `#each`
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2016-01-29 19:13:01 +00:00
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abstract def move_next : Bool
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2016-01-28 23:31:35 +00:00
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2016-01-30 22:46:43 +00:00
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# TODO def empty? : Bool, handle internally with move_next (?)
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2016-01-31 22:40:02 +00:00
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# Returns the number of columns in the result
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2016-01-30 00:57:00 +00:00
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abstract def column_count : Int32
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2016-01-31 22:40:02 +00:00
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# Returns the name of the column in `index` 0-based position.
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2016-01-30 00:57:00 +00:00
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abstract def column_name(index : Int32) : String
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2016-01-31 22:40:02 +00:00
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2016-06-28 17:02:08 +00:00
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# Reads the next column value
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abstract def read
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2016-01-30 00:57:00 +00:00
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2016-06-28 17:02:08 +00:00
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# Reads the next column value as a **type**
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def read(type : T.class) : T
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read.as(T)
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2016-06-21 15:10:09 +00:00
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end
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2016-02-02 00:55:30 +00:00
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2016-06-28 17:02:08 +00:00
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# Reads the next columns and returns a tuple of the values.
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def read(*types : Class)
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internal_read(*types)
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2016-04-10 18:21:10 +00:00
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end
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2016-06-28 17:02:08 +00:00
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private def internal_read(*types : *T)
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{% begin %}
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Tuple.new(
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{% for type in T %}
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read({{type.instance}}),
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{% end %}
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)
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{% end %}
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2016-04-14 18:18:09 +00:00
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end
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2016-02-02 00:55:30 +00:00
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# def read_blob
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# yield ... io ....
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# end
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# def read_text
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# yield ... io ....
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# end
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2016-01-28 23:31:35 +00:00
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end
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end
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