Class: PG::TypeMapByColumn

Inherits:
TypeMap
  • Object
show all
Defined in:
ext/pg_type_map_by_column.c,
lib/pg/type_map_by_column.rb,
ext/pg_type_map_by_column.c

Overview

This type map casts values by a coder assigned per field/column.

Each PG:TypeMapByColumn has a fixed list of either encoders or decoders, that is defined at #new . A type map with encoders is usable for type casting query bind parameters and COPY data for PG::Connection#put_copy_data . A type map with decoders is usable for type casting of result values and COPY data from PG::Connection#get_copy_data .

PG::TypeMapByColumns are in particular useful in conjunction with prepared statements, since they can be cached alongside with the statement handle.

This type map strategy is also used internally by PG::TypeMapByOid, when the number of rows of a result set exceeds a given limit.

Instance Method Summary collapse

Methods inherited from TypeMap

#fit_to_query, #fit_to_result

Constructor Details

#PG::TypeMapByColumn.new(coders) ⇒ Object

Builds a new type map and assigns a list of coders for the given column. coders must be an Array of PG::Coder objects or nil values. The length of the Array corresponds to the number of columns or bind parameters this type map is usable for.

A nil value will cast the given field to a String object.


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# File 'ext/pg_type_map_by_column.c', line 165

static VALUE
pg_tmbc_init(VALUE self, VALUE conv_ary)
{
	int i;
	t_tmbc *this;
	int conv_ary_len;

	Check_Type(self, T_DATA);
	Check_Type(conv_ary, T_ARRAY);
	conv_ary_len = RARRAY_LEN(conv_ary);
	this = xmalloc(sizeof(t_tmbc) + sizeof(struct pg_tmbc_converter) * conv_ary_len);
	/* Set nfields to 0 at first, so that GC mark function doesn't access uninitialized memory. */
	this->nfields = 0;
	this->typemap = pg_tmbc_default_typemap;
	DATA_PTR(self) = this;

	for(i=0; i<conv_ary_len; i++)
	{
		VALUE obj = rb_ary_entry(conv_ary, i);

		if( obj == Qnil ){
			/* no type cast */
			this->convs[i].cconv = NULL;
		} else if( rb_obj_is_kind_of(obj, rb_cPG_Coder) ){
			Data_Get_Struct(obj, t_pg_coder, this->convs[i].cconv);
		} else {
			rb_raise(rb_eArgError, "argument %d has invalid type %s (should be nil or some kind of PG::Coder)",
							 i+1, rb_obj_classname( obj ));
		}
	}

	this->nfields = conv_ary_len;

	return self;
}

Instance Method Details

#coders ⇒ Array

Array of PG::Coder objects. The length of the Array corresponds to the number of columns or bind parameters this type map is usable for.

Returns:

  • (Array) 

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# File 'ext/pg_type_map_by_column.c', line 208

static VALUE
pg_tmbc_coders(VALUE self)
{
	int i;
	t_tmbc *this = DATA_PTR( self );
	VALUE ary_coders = rb_ary_new();

	for( i=0; i<this->nfields; i++){
		t_pg_coder *conv = this->convs[i].cconv;
		if( conv ) {
			rb_ary_push( ary_coders, conv->coder_obj );
		} else {
			rb_ary_push( ary_coders, Qnil );
		}
	}

	return rb_obj_freeze(ary_coders);
}

#inspect ⇒ Object 


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# File 'lib/pg/type_map_by_column.rb', line 11

def inspect
	type_strings = coders.map{|c| c ? "#{c.name}:#{c.format}" : 'nil' }
	"#<#{self.class} #{type_strings.join(' ')}>"
end

#oids ⇒ Object

Returns the type oids of the assigned coders.


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# File 'lib/pg/type_map_by_column.rb', line 7

def oids
	coders.map{|c| c.oid if c }
end