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DBI::StatementHandle

StatementHandle is the interface the consumer sees after successfully issuing a DatabaseHandle#prepare. They may also be exposed through other methods that send statements to the database.

Almost all methods in this class will raise InterfaceError if the statement is already finished.

Attributes

dbh[RW]
raise_error[RW]

Public Class Methods

new(handle, fetchable=false, prepared=true, convert_types=true, executed=false) click to toggle source
# File lib/dbi/handles/statement.rb, line 17
def initialize(handle, fetchable=false, prepared=true, convert_types=true, executed=false)
    super(handle)
    @fetchable = fetchable
    @prepared  = prepared     # only false if immediate execute was used
    @executed  = executed     # only true if the statement was already executed.
    @cols = nil
    @coltypes = nil
    @convert_types = convert_types

    if @fetchable
        @row = DBI::Row.new(column_names, column_types, nil, @convert_types)
    else
        @row = nil
    end
end

Public Instance Methods

[](attr) click to toggle source

Get an attribute from the StatementHandle object.

# File lib/dbi/handles/statement.rb, line 358
def [] (attr)
    sanity_check
    @handle[attr]
end
[]=(attr, val) click to toggle source

Set an attribute on the StatementHandle object.

# File lib/dbi/handles/statement.rb, line 364
def []= (attr, val)
    sanity_check
    @handle[attr] = val
end
bind_coltype(pos, type) click to toggle source

Instruct successive calls to fetch to cast the type returned into `type`, for row position `pos`. Like all bind_* calls, `pos` indexes starting at 1.

`type` is an object with the DBI::Type calling convention.

This call must be called after execute has successfully ran, otherwise it will raise InterfaceError.

Example:

# `foo` is an integer and this statement will return two rows. 
sth = dbh.prepare("select foo from bar") 
# would raise InterfaceError if called here
sth.execute

sth.bind_coltype(1, DBI::Type::Varchar) 
# would normally use DBI::Type::Integer and return a Fixnum. We'll make it a string.
sth.fetch => ["1"]

# Here we coerce it to Float.
sth.bind_coltype(1, DBI::Type::Float)
sth.fetch => [1.0]
sth.finish
# File lib/dbi/handles/statement.rb, line 72
def bind_coltype(pos, type)
    sanity_check({:prepared => true, :executed => true})
    
    coltypes = column_types

    if (pos - 1) < 0
        raise InterfaceError, "bind positions index starting at 1"
    end

    coltypes[pos-1] = type
    @row = DBI::Row.new(column_names, coltypes, nil, @convert_types)
end
bind_param(param, value, attribs=nil) click to toggle source

Just like BaseStatement#bind_param, but will attempt to convert the type if it's supposed to, adhering to the DBD's current ruleset.

# File lib/dbi/handles/statement.rb, line 89
def bind_param(param, value, attribs=nil)
    sanity_check({ :prepared => true })

    if @convert_types
        value = DBI::Utils::ConvParam.conv_param(dbh.driver_name, value)[0]
    end

    @handle.bind_param(param, value, attribs)
end
cancel() click to toggle source

Cancel the query, closing any open result cursors and truncating any result sets.

The difference between this and finish is that cancelled statements may be re-executed.

# File lib/dbi/handles/statement.rb, line 146
def cancel
    sanity_check
    @handle.cancel if @fetchable
    @fetchable = false
end
column_info() click to toggle source

See BaseStatement#column_info.

# File lib/dbi/handles/statement.rb, line 183
def column_info
    sanity_check
    @handle.column_info.collect {|col| ColumnInfo.new(col) }
end
column_names() click to toggle source

Obtains the column names for this query as an array.

# File lib/dbi/handles/statement.rb, line 155
def column_names
    sanity_check
    return @cols unless @cols.nil?
    @cols = @handle.column_info.collect {|col| col['name'] }
end
column_types() click to toggle source

Obtain the type mappings for the columns in this query based on ColumnInfo data on the query.

The result will be a position-dependent array of objects that conform to the DBI::Type calling syntax.

# File lib/dbi/handles/statement.rb, line 168
def column_types
    sanity_check
    return @coltypes unless @coltypes.nil?
    @coltypes = @handle.column_info.collect do |col| 
        if col['dbi_type']
            col['dbi_type']
        else
            DBI::TypeUtil.type_name_to_module(col['type_name'])
        end
    end
end
each(&p) click to toggle source

Synonym for fetch with a block.

# File lib/dbi/handles/statement.rb, line 236
def each(&p)
    sanity_check({:fetchable => true, :prepared => true, :executed => true})
    raise InterfaceError, "No block given" unless block_given?

    fetch(&p)
end
execute(*bindvars) click to toggle source

Execute the statement.

This generally means that the statement will be sent to the database and some form of result cursor will be obtained, but is ultimately driver-dependent.

If arguments are supplied, these are fed to bind_param.

# File lib/dbi/handles/statement.rb, line 107
def execute(*bindvars)
    cancel     # cancel before 
    sanity_check({:prepared => true })

    if @convert_types
        bindvars = DBI::Utils::ConvParam.conv_param(dbh.driver_name, *bindvars)
    end

    @handle.bind_params(*bindvars)
    @handle.execute
    @fetchable = true
    @executed = true

    # TODO:?
    #if @row.nil?
    @row = DBI::Row.new(column_names, column_types, nil, @convert_types)
    #end
    return nil
end
fetch(&p) click to toggle source

See BaseStatement#fetch.

fetch can also take a block which will be applied to each row in a similar fashion to Enumerable#collect. See each.

# File lib/dbi/handles/statement.rb, line 207
def fetch(&p)
    sanity_check({ :fetchable => true, :prepared => true, :executed => true })

    if block_given? 
        while (res = @handle.fetch) != nil
            @row = @row.dup
            @row.set_values(res)
            yield @row
        end
        @handle.cancel
        @fetchable = false
        return nil
    else
        res = @handle.fetch
        if res.nil?
            @handle.cancel
            @fetchable = false
        else
            @row = @row.dup
            @row.set_values(res)
            res = @row
        end
        return res
    end
end
fetch_all() click to toggle source

Fetch the entire result set. Result is array of DBI::Row.

# File lib/dbi/handles/statement.rb, line 321
def fetch_all
    sanity_check({:fetchable => true, :prepared => true, :executed => true})

    cols = column_names
    fetched_rows = []

    begin
        while row = fetch do
            fetched_rows.push(row)
        end
    rescue Exception
    end

    @handle.cancel
    @fetchable = false

    return fetched_rows
end
fetch_array() click to toggle source

Similar to fetch, but returns Array of Array instead of Array of DBI::Row objects (and therefore does not perform type mapping). This is basically a way to get the raw data from the DBD.

# File lib/dbi/handles/statement.rb, line 248
def fetch_array
    sanity_check({:fetchable => true, :prepared => true, :executed => true})

    if block_given? 
        while (res = @handle.fetch) != nil
            yield res
        end
        @handle.cancel
        @fetchable = false
        return nil
    else
        res = @handle.fetch
        if res.nil?
            @handle.cancel
            @fetchable = false
        end
        return res
    end
end
fetch_hash() click to toggle source

Map the columns and results into an Array of Hash resultset.

No type conversion is performed here. Expect this to change in 0.6.0.

# File lib/dbi/handles/statement.rb, line 273
def fetch_hash
    sanity_check({:fetchable => true, :prepared => true, :executed => true})

    cols = column_names

    if block_given? 
        while (row = @handle.fetch) != nil
            hash = {}
            row.each_with_index {|v,i| hash[cols[i]] = v} 
            yield hash
        end
        @handle.cancel
        @fetchable = false
        return nil
    else
        row = @handle.fetch
        if row.nil?
            @handle.cancel
            @fetchable = false
            return nil
        else
            hash = {}
            row.each_with_index {|v,i| hash[cols[i]] = v} 
            return hash
        end
    end
end
fetch_many(cnt) click to toggle source

Fetch `cnt` rows. Result is array of DBI::Row

# File lib/dbi/handles/statement.rb, line 304
def fetch_many(cnt)
    sanity_check({:fetchable => true, :prepared => true, :executed => true})

    cols = column_names
    rows = @handle.fetch_many(cnt)
    if rows.nil? or rows.empty?
        @handle.cancel
        @fetchable = false
        return []
    else
        return rows.collect{|r| tmp = @row.dup; tmp.set_values(r); tmp }
    end
end
fetch_scroll(direction, offset=1) click to toggle source

See BaseStatement#fetch_scroll.

# File lib/dbi/handles/statement.rb, line 343
def fetch_scroll(direction, offset=1)
    sanity_check({:fetchable => true, :prepared => true, :executed => true})

    row = @handle.fetch_scroll(direction, offset)
    if row.nil?
        #@handle.cancel
        #@fetchable = false
        return nil
    else
        @row.set_values(row)
        return @row
    end
end
fetchable?() click to toggle source

Returns true if the statement is believed to return data upon fetch.

The current reliability of this (and the concept in general) is suspect.

# File lib/dbi/handles/statement.rb, line 43
def fetchable?
    @fetchable
end
finish() click to toggle source

Finish the statement, causing the database to release all assets related to it (any result cursors, normally).

StatementHandles that have already been finished will normally be inoperable and unavailable for further use.

# File lib/dbi/handles/statement.rb, line 134
def finish
    sanity_check
    @handle.finish
    @handle = nil
end
finished?() click to toggle source

Returns true if the StatementHandle has had finish called on it, explicitly or otherwise.

# File lib/dbi/handles/statement.rb, line 35
def finished?
    @handle.nil?
end
rows() click to toggle source

Should return the row modified count as the result of statement execution.

However, some low-level drivers do not supply this information or supply misleading information (> 0 rows for read-only select statements, f.e.)

# File lib/dbi/handles/statement.rb, line 195
def rows
    sanity_check
    @handle.rows
end

Protected Instance Methods

check_executed() click to toggle source
# File lib/dbi/handles/statement.rb, line 398
def check_executed
    raise InterfaceError, "Statement hasn't been executed yet." unless @executed
end
check_fetchable() click to toggle source
# File lib/dbi/handles/statement.rb, line 392
def check_fetchable
    if !@fetchable and @raise_error
        raise InterfaceError, "Statement does not have any data for fetching." 
    end
end
check_prepared() click to toggle source
# File lib/dbi/handles/statement.rb, line 388
def check_prepared
    raise InterfaceError, "Statement wasn't prepared before." unless @prepared
end
check_statement(stmt) click to toggle source

basic sanity checks for statements

# File lib/dbi/handles/statement.rb, line 403
def check_statement(stmt)
    raise InterfaceError, "Statement is empty, or contains nothing but whitespace" if stmt !~ /\S/
end
sanity_check(params={}) click to toggle source
# File lib/dbi/handles/statement.rb, line 371
def sanity_check(params={})
    raise InterfaceError, "Statement was already closed!" if @handle.nil?

    params.each_key do |key|
        case key
        when :fetchable
            check_fetchable
        when :executed
            check_executed
        when :prepared
            check_prepared
        when :statement
            check_statement(params[:statement])
        end
    end
end

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