PG::

Result class

Superclass rb_cObject
Included Modules
  • Enumerable
  • rb_mPGconstants

The class to represent the query result tuples (rows). An instance of this class is created as the result of every query. All result rows and columns are stored in an immutable memory block attached to the PG::Result object unless streaming is used.

A PG::Result has various ways to retrieve the result data:

require 'pg'
conn = PG.connect(dbname: 'test')
res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.num_fields       # 3
res.num_tuples       # 1
res.fname(2)         # "c"
res.fields           # ["a", "b", "c"]
res.getvalue(0,0)    # '1'
res[0]               # {"a" => "1", "b" => "2", "c" => "3"}
res.tuple_values(0)  # ["1", "2", nil]
res.tuple(0)         # #<PG::Tuple a: "1", b: "2", c: nil>
res.values           # [["1", "2", nil]]
res.field_values(:a) # ["1"]
res.column_values(1) # ["2"]
res.each.first       # {"a" => "1", "b" => "2", "c" => nil}
res.each_row.first   # ["1", "2", nil]

Whenever a value is accessed it is casted to a Ruby object by the assigned type_map which is PG::TypeMapAllStrings by default. Similarly field names can be retrieved either as strings (default) or as symbols which can be switched per field_name_type= .

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.type_map = PG::TypeMapByColumn.new([PG::TextDecoder::Integer.new]*3)
res.field_name_type = :symbol
res.fname(2)         # :c
res.fields           # [:a, :b, :c]
res.getvalue(0,0)    # 1
res[0]               # {a: 1, b: 2, c: nil}
res.tuple_values(0)  # [1, 2, nil]
res.tuple(0)         # #<PG::Tuple a: 1, b: 2, c: nil>
res.values           # [[1, 2, nil]]
res.field_values(:a) # [1]
res.column_values(1) # [2]
res.each.first       # {a: 1, b: 2, c: nil}
res.each_row.first   # [1, 2, nil]

Since pg-1.1 the amount of memory in use by a PG::Result object is estimated and passed to ruby’s garbage collector. You can invoke the clear method to force deallocation of memory of the instance when finished with the result for better memory performance.

Public Class Methods

PG::Result.res_status( status ) → String

Returns the string representation of result_status.

static VALUE
pgresult_s_res_status(VALUE self, VALUE status)
{
        return rb_utf8_str_new_cstr(PQresStatus(NUM2INT(status)));
}

Public Instance Methods

res[ n ] → Hash

Returns tuple n as a hash.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res[0]               # {"a" => "1", "b" => "2", "c" => "3"}

static VALUE
pgresult_aref(VALUE self, VALUE index)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        int tuple_num = NUM2INT(index);
        int field_num;
        int num_tuples = PQntuples(this->pgresult);
        VALUE tuple;

        if( this->nfields == -1 )
                pgresult_init_fnames( self );

        if ( tuple_num < 0 || tuple_num >= num_tuples )
                rb_raise( rb_eIndexError, "Index %d is out of range", tuple_num );

        tuple = rb_hash_new_capa(this->nfields);
        for ( field_num = 0; field_num < this->nfields; field_num++ ) {
                VALUE val = this->p_typemap->funcs.typecast_result_value(this->p_typemap, self, tuple_num, field_num);
                rb_hash_aset( tuple, this->fnames[field_num], val );
        }

        return tuple;
}
autoclear? → boolean

Returns true if the underlying C struct will be cleared at the end of a callback. This applies only to Result objects received by the block to PG::Connection#set_notice_receiver .

All other Result objects are automatically cleared by the GC when the object is no longer in use or manually by PG::Result#clear .

static VALUE
pgresult_autoclear_p( VALUE self )
{
        t_pg_result *this = pgresult_get_this(self);
        return this->autoclear ? Qtrue : Qfalse;
}
binary_tuples() → Integer

Returns 1 if the PG::Result contains binary data and 0 if it contains text data.

This function is deprecated (except for its use in connection with COPY), because it is possible for a single PG::Result to contain text data in some columns and binary data in others. Result#fformat is preferred. binary_tuples returns 1 only if all columns of the result are binary (format 1).

static VALUE
pgresult_binary_tuples(VALUE self)
{
        return INT2NUM(PQbinaryTuples(pgresult_get(self)));
}
check → nil

Raises appropriate exception if PG::Result is in a bad state, which is:

  • PGRES_BAD_RESPONSE

  • PGRES_FATAL_ERROR

  • PGRES_NONFATAL_ERROR

  • PGRES_PIPELINE_ABORTED

VALUE
pg_result_check( VALUE self )
{
        t_pg_result *this = pgresult_get_this(self);
        VALUE error, exception, klass;
        char * sqlstate;

        if(this->pgresult == NULL)
        {
                PGconn *conn = pg_get_pgconn(this->connection);
                error = rb_str_new2( PQerrorMessage(conn) );
        }
        else
        {
                switch (PQresultStatus(this->pgresult))
                {
                case PGRES_TUPLES_OK:
                case PGRES_COPY_OUT:
                case PGRES_COPY_IN:
                case PGRES_COPY_BOTH:
                case PGRES_SINGLE_TUPLE:
                case PGRES_EMPTY_QUERY:
                case PGRES_COMMAND_OK:
#ifdef HAVE_PQENTERPIPELINEMODE
                case PGRES_PIPELINE_SYNC:
#endif
#ifdef HAVE_PQSETCHUNKEDROWSMODE
                case PGRES_TUPLES_CHUNK:
#endif
                        return self;
                case PGRES_BAD_RESPONSE:
                case PGRES_FATAL_ERROR:
                case PGRES_NONFATAL_ERROR:
#ifdef HAVE_PQENTERPIPELINEMODE
                case PGRES_PIPELINE_ABORTED:
#endif
                        error = rb_str_new2( PQresultErrorMessage(this->pgresult) );
                        break;
                default:
                        error = rb_str_new2( "internal error : unknown result status." );
                }
        }

        PG_ENCODING_SET_NOCHECK( error, this->enc_idx );

        sqlstate = PQresultErrorField( this->pgresult, PG_DIAG_SQLSTATE );
        klass = lookup_error_class( sqlstate );
        exception = rb_exc_new3( klass, error );
        rb_iv_set( exception, "@connection", this->connection );
        rb_iv_set( exception, "@result", this->pgresult ? self : Qnil );
        rb_exc_raise( exception );

        /* Not reached */
        return self;
}
Also aliased as: check_result
check_result()

Raises appropriate exception if PG::Result is in a bad state, which is:

  • PGRES_BAD_RESPONSE

  • PGRES_FATAL_ERROR

  • PGRES_NONFATAL_ERROR

  • PGRES_PIPELINE_ABORTED

Alias for: check
clear() → nil

Clears the PG::Result object as the result of a query. This frees all underlying memory consumed by the result object. Afterwards access to result methods raises PG::Error “result has been cleared”.

Explicit calling clear can lead to better memory performance, but is not generally necessary. Special care must be taken when PG::Tuple objects are used. In this case clear must not be called unless all PG::Tuple objects of this result are fully materialized.

If PG::Result#autoclear? is true then the result is only marked as cleared but clearing the underlying C struct will happen when the callback returns.

VALUE
pg_result_clear(VALUE self)
{
        t_pg_result *this = pgresult_get_this(self);
        rb_check_frozen(self);
        pgresult_clear( this );
        return Qnil;
}
cleared? → boolean

Returns true if the backend result memory has been freed.

static VALUE
pgresult_cleared_p( VALUE self )
{
        t_pg_result *this = pgresult_get_this(self);
        return this->pgresult ? Qfalse : Qtrue;
}
cmd_status() → String

Returns the status string of the last query command.

static VALUE
pgresult_cmd_status(VALUE self)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        VALUE ret = rb_str_new2(PQcmdStatus(this->pgresult));
        PG_ENCODING_SET_NOCHECK(ret, this->enc_idx);
        return ret;
}
cmd_tuples() → Integer

Returns the number of tuples (rows) affected by the SQL command.

If the SQL command that generated the PG::Result was not one of:

  • SELECT

  • CREATE TABLE AS

  • INSERT

  • UPDATE

  • DELETE

  • MOVE

  • FETCH

  • COPY

  • an EXECUTE of a prepared query that contains an INSERT, UPDATE, or DELETE statement

or if no tuples were affected, 0 is returned.

static VALUE
pgresult_cmd_tuples(VALUE self)
{
        long n;
        n = strtol(PQcmdTuples(pgresult_get(self)),NULL, 10);
        return LONG2NUM(n);
}
Also aliased as: cmdtuples
cmdtuples()

Returns the number of tuples (rows) affected by the SQL command.

If the SQL command that generated the PG::Result was not one of:

  • SELECT

  • CREATE TABLE AS

  • INSERT

  • UPDATE

  • DELETE

  • MOVE

  • FETCH

  • COPY

  • an EXECUTE of a prepared query that contains an INSERT, UPDATE, or DELETE statement

or if no tuples were affected, 0 is returned.

Alias for: cmd_tuples
column_values( n ) → array

Returns an Array of the values from the nth column of each tuple in the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.column_values(1) # ["2"]

static VALUE
pgresult_column_values(VALUE self, VALUE index)
{
        int col = NUM2INT( index );
        return make_column_result_array( self, col );
}
each{ |tuple| ... }

Yields a Hash object for each row in the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.each.first       # {"a" => "1", "b" => "2", "c" => nil}

static VALUE
pgresult_each(VALUE self)
{
        PGresult *result;
        int tuple_num;

        RETURN_SIZED_ENUMERATOR(self, 0, NULL, pgresult_ntuples_for_enum);

        result = pgresult_get(self);

        for(tuple_num = 0; tuple_num < PQntuples(result); tuple_num++) {
                rb_yield(pgresult_aref(self, INT2NUM(tuple_num)));
        }
        return self;
}
each_row { |row| ... }

Yields an Array object for each row in the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.each_row.first   # ["1", "2", nil]

static VALUE
pgresult_each_row(VALUE self)
{
        t_pg_result *this;
        int row;
        int field;
        int num_rows;
        int num_fields;

        RETURN_SIZED_ENUMERATOR(self, 0, NULL, pgresult_ntuples_for_enum);

        this = pgresult_get_this_safe(self);
        num_rows = PQntuples(this->pgresult);
        num_fields = PQnfields(this->pgresult);

        for ( row = 0; row < num_rows; row++ ) {
                PG_VARIABLE_LENGTH_ARRAY(VALUE, row_values, num_fields, PG_MAX_COLUMNS)

                /* populate the row */
                for ( field = 0; field < num_fields; field++ ) {
                        row_values[field] = this->p_typemap->funcs.typecast_result_value(this->p_typemap, self, row, field);
                }
                rb_yield( rb_ary_new4( num_fields, row_values ));
        }

        return Qnil;
}
error_field(fieldcode) → String

Returns the individual field of an error.

fieldcode is one of:

  • PG_DIAG_SEVERITY

  • PG_DIAG_SQLSTATE

  • PG_DIAG_MESSAGE_PRIMARY

  • PG_DIAG_MESSAGE_DETAIL

  • PG_DIAG_MESSAGE_HINT

  • PG_DIAG_STATEMENT_POSITION

  • PG_DIAG_INTERNAL_POSITION

  • PG_DIAG_INTERNAL_QUERY

  • PG_DIAG_CONTEXT

  • PG_DIAG_SOURCE_FILE

  • PG_DIAG_SOURCE_LINE

  • PG_DIAG_SOURCE_FUNCTION

An example:

begin
    conn.exec( "SELECT * FROM nonexistent_table" )
rescue PG::Error => err
    p [
        err.result.error_field( PG::Result::PG_DIAG_SEVERITY ),
        err.result.error_field( PG::Result::PG_DIAG_SQLSTATE ),
        err.result.error_field( PG::Result::PG_DIAG_MESSAGE_PRIMARY ),
        err.result.error_field( PG::Result::PG_DIAG_MESSAGE_DETAIL ),
        err.result.error_field( PG::Result::PG_DIAG_MESSAGE_HINT ),
        err.result.error_field( PG::Result::PG_DIAG_STATEMENT_POSITION ),
        err.result.error_field( PG::Result::PG_DIAG_INTERNAL_POSITION ),
        err.result.error_field( PG::Result::PG_DIAG_INTERNAL_QUERY ),
        err.result.error_field( PG::Result::PG_DIAG_CONTEXT ),
        err.result.error_field( PG::Result::PG_DIAG_SOURCE_FILE ),
        err.result.error_field( PG::Result::PG_DIAG_SOURCE_LINE ),
        err.result.error_field( PG::Result::PG_DIAG_SOURCE_FUNCTION ),
    ]
end

Outputs:

["ERROR", "42P01", "relation \"nonexistent_table\" does not exist", nil, nil,
 "15", nil, nil, nil, "path/to/parse_relation.c", "857", "parserOpenTable"]

static VALUE
pgresult_error_field(VALUE self, VALUE field)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        int fieldcode = NUM2INT( field );
        char * fieldstr = PQresultErrorField( this->pgresult, fieldcode );
        VALUE ret = Qnil;

        if ( fieldstr ) {
                ret = rb_str_new2( fieldstr );
                PG_ENCODING_SET_NOCHECK( ret, this->enc_idx );
        }

        return ret;
}
Also aliased as: result_error_field
error_message() → String

Returns the error message of the command as a string.

static VALUE
pgresult_error_message(VALUE self)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        VALUE ret = rb_str_new2(PQresultErrorMessage(this->pgresult));
        PG_ENCODING_SET_NOCHECK(ret, this->enc_idx);
        return ret;
}
Also aliased as: result_error_message
fformat( column_number ) → Integer

Returns the format (0 for text, 1 for binary) of column column_number.

Raises ArgumentError if column_number is out of range.

static VALUE
pgresult_fformat(VALUE self, VALUE column_number)
{
        PGresult *result = pgresult_get(self);
        int fnumber = NUM2INT(column_number);
        if (fnumber < 0 || fnumber >= PQnfields(result)) {
                rb_raise(rb_eArgError, "Column number is out of range: %d",
                        fnumber);
        }
        return INT2FIX(PQfformat(result, fnumber));
}
field_name_type → Symbol

Get type of field names.

See description at field_name_type=

static VALUE
pgresult_field_name_type_get(VALUE self)
{
        t_pg_result *this = pgresult_get_this(self);
        if( this->flags & PG_RESULT_FIELD_NAMES_SYMBOL ){
                return sym_symbol;
        } else if( this->flags & PG_RESULT_FIELD_NAMES_STATIC_SYMBOL ){
                return sym_static_symbol;
        } else {
                return sym_string;
        }
}
field_name_type = Symbol

Set type of field names specific to this result. It can be set to one of:

  • :string to use String based field names

  • :symbol to use Symbol based field names

  • :static_symbol to use pinned Symbol (can not be garbage collected) - Don’t use this, it will probably be removed in future.

The default is retrieved from PG::Connection#field_name_type , which defaults to :string .

This setting affects several result methods:

The type of field names can only be changed before any of the affected methods have been called.

static VALUE
pgresult_field_name_type_set(VALUE self, VALUE sym)
{
        t_pg_result *this = pgresult_get_this(self);

        rb_check_frozen(self);
        if( this->nfields != -1 ) rb_raise(rb_eArgError, "field names are already materialized");

        this->flags &= ~PG_RESULT_FIELD_NAMES_MASK;
        if( sym == sym_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_SYMBOL;
        else if ( sym == sym_static_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_STATIC_SYMBOL;
        else if ( sym == sym_string );
        else rb_raise(rb_eArgError, "invalid argument %+"PRIsVALUE, sym);

        return sym;
}
field_names_as(type)

Set the data type for all field name returning methods.

type: a Symbol defining the field name type.

This method is equal to field_name_type= , but returns self, so that calls can be chained.

# File lib/pg/result.rb, line 25
def field_names_as(type)
        self.field_name_type = type
        return self
end
field_values( field ) → array

Returns an Array of the values from the given field of each tuple in the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.field_values(:a) # ["1"]

static VALUE
pgresult_field_values( VALUE self, VALUE field )
{
        PGresult *result = pgresult_get( self );
        const char *fieldname;
        int fnum;

        if( RB_TYPE_P(field, T_SYMBOL) ) field = rb_sym_to_s( field );
        fieldname = StringValueCStr( field );
        fnum = PQfnumber( result, fieldname );

        if ( fnum < 0 )
                rb_raise( rb_eIndexError, "no such field '%s' in result", fieldname );

        return make_column_result_array( self, fnum );
}
fields() → Array

Depending on field_name_type= returns an array of strings or symbols representing the names of the fields in the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.fields           # ["a", "b", "c"]

static VALUE
pgresult_fields(VALUE self)
{
        t_pg_result *this = pgresult_get_this_safe(self);

        if( this->nfields == -1 )
                pgresult_init_fnames( self );

        return rb_ary_new4( this->nfields, this->fnames );
}
fmod( column_number )

Returns the type modifier associated with column column_number. See the ftype method for an example of how to use this.

Raises an ArgumentError if column_number is out of range.

static VALUE
pgresult_fmod(VALUE self, VALUE column_number)
{
        PGresult *result = pgresult_get(self);
        int fnumber = NUM2INT(column_number);
        int modifier;
        if (fnumber < 0 || fnumber >= PQnfields(result)) {
                rb_raise(rb_eArgError, "Column number is out of range: %d",
                        fnumber);
        }
        modifier = PQfmod(result,fnumber);

        return INT2NUM(modifier);
}
fname( index ) → String or Symbol

Returns the name of the column corresponding to index. Depending on field_name_type= it’s a String or Symbol.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.fname(2)       # "c"

static VALUE
pgresult_fname(VALUE self, VALUE index)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        int i = NUM2INT(index);
        char *cfname;

        if (i < 0 || i >= PQnfields(this->pgresult)) {
                rb_raise(rb_eArgError,"invalid field number %d", i);
        }

        cfname = PQfname(this->pgresult, i);
        return pg_cstr_to_sym(cfname, this->flags, this->enc_idx);
}
fnumber( name ) → Integer

Returns the index of the field specified by the string name. The given name is treated like an identifier in an SQL command, that is, it is downcased unless double-quoted. For example, given a query result generated from the SQL command:

result = conn.exec( %{SELECT 1 AS FOO, 2 AS "BAR"} )

we would have the results:

result.fname( 0 )            # => "foo"
result.fname( 1 )            # => "BAR"
result.fnumber( "FOO" )      # => 0
result.fnumber( "foo" )      # => 0
result.fnumber( "BAR" )      # => ArgumentError
result.fnumber( %{"BAR"} )   # => 1

Raises an ArgumentError if the specified name isn’t one of the field names; raises a TypeError if name is not a String.

static VALUE
pgresult_fnumber(VALUE self, VALUE name)
{
        int n;

        Check_Type(name, T_STRING);

        n = PQfnumber(pgresult_get(self), StringValueCStr(name));
        if (n == -1) {
                rb_raise(rb_eArgError,"Unknown field: %s", StringValueCStr(name));
        }
        return INT2FIX(n);
}
freeze

Freeze the PG::Result object and unlink the result from the related PG::Connection.

A frozen PG::Result object doesn’t allow any streaming and it can’t be cleared. It also denies setting a type_map or field_name_type.

static VALUE
pg_result_freeze(VALUE self)
{
        t_pg_result *this = pgresult_get_this(self);

        ensure_init_for_tuple(self);
        RB_OBJ_WRITE(self, &this->connection, Qnil);
        return rb_call_super(0, NULL);
}
fsize( index )

Returns the size of the field type in bytes. Returns -1 if the field is variable sized.

res = conn.exec("SELECT myInt, myVarChar50 FROM foo")
res.size(0) => 4
res.size(1) => -1

static VALUE
pgresult_fsize(VALUE self, VALUE index)
{
        PGresult *result;
        int i = NUM2INT(index);

        result = pgresult_get(self);
        if (i < 0 || i >= PQnfields(result)) {
                rb_raise(rb_eArgError,"invalid field number %d", i);
        }
        return INT2NUM(PQfsize(result, i));
}
ftable( column_number ) → Integer

Returns the Oid of the table from which the column column_number was fetched.

Raises ArgumentError if column_number is out of range or if the Oid is undefined for that column.

static VALUE
pgresult_ftable(VALUE self, VALUE column_number)
{
        Oid n ;
        int col_number = NUM2INT(column_number);
        PGresult *pgresult = pgresult_get(self);

        if( col_number < 0 || col_number >= PQnfields(pgresult))
                rb_raise(rb_eArgError,"Invalid column index: %d", col_number);

        n = PQftable(pgresult, col_number);
        return UINT2NUM(n);
}
ftablecol( column_number ) → Integer

Returns the column number (within its table) of the table from which the column column_number is made up.

Raises ArgumentError if column_number is out of range or if the column number from its table is undefined for that column.

static VALUE
pgresult_ftablecol(VALUE self, VALUE column_number)
{
        int col_number = NUM2INT(column_number);
        PGresult *pgresult = pgresult_get(self);

        int n;

        if( col_number < 0 || col_number >= PQnfields(pgresult))
                rb_raise(rb_eArgError,"Invalid column index: %d", col_number);

        n = PQftablecol(pgresult, col_number);
        return INT2FIX(n);
}
ftype( column_number ) → Integer

Returns the data type associated with column_number.

The integer returned is the internal OID number (in PostgreSQL) of the type. To get a human-readable value for the type, use the returned OID and the field’s fmod value with the format_type() SQL function:

# Get the type of the second column of the result 'res'
typename = conn.
  exec( "SELECT format_type($1,$2)", [res.ftype(1), res.fmod(1)] ).
  getvalue( 0, 0 )

Raises an ArgumentError if column_number is out of range.

static VALUE
pgresult_ftype(VALUE self, VALUE index)
{
        PGresult* result = pgresult_get(self);
        int i = NUM2INT(index);
        if (i < 0 || i >= PQnfields(result)) {
                rb_raise(rb_eArgError, "invalid field number %d", i);
        }
        return UINT2NUM(PQftype(result, i));
}
getisnull(tuple_position, field_position) → boolean

Returns true if the specified value is nil; false otherwise.

static VALUE
pgresult_getisnull(VALUE self, VALUE tup_num, VALUE field_num)
{
        PGresult *result;
        int i = NUM2INT(tup_num);
        int j = NUM2INT(field_num);

        result = pgresult_get(self);
        if (i < 0 || i >= PQntuples(result)) {
                rb_raise(rb_eArgError,"invalid tuple number %d", i);
        }
        if (j < 0 || j >= PQnfields(result)) {
                rb_raise(rb_eArgError,"invalid field number %d", j);
        }
        return PQgetisnull(result, i, j) ? Qtrue : Qfalse;
}
getlength( tup_num, field_num ) → Integer

Returns the (String) length of the field in bytes.

Equivalent to res.value(tup_num,field_num).length.

static VALUE
pgresult_getlength(VALUE self, VALUE tup_num, VALUE field_num)
{
        PGresult *result;
        int i = NUM2INT(tup_num);
        int j = NUM2INT(field_num);

        result = pgresult_get(self);
        if (i < 0 || i >= PQntuples(result)) {
                rb_raise(rb_eArgError,"invalid tuple number %d", i);
        }
        if (j < 0 || j >= PQnfields(result)) {
                rb_raise(rb_eArgError,"invalid field number %d", j);
        }
        return INT2FIX(PQgetlength(result, i, j));
}
getvalue( tup_num, field_num )

Returns the value in tuple number tup_num, field field_num, or nil if the field is NULL.

static VALUE
pgresult_getvalue(VALUE self, VALUE tup_num, VALUE field_num)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        int i = NUM2INT(tup_num);
        int j = NUM2INT(field_num);

        if(i < 0 || i >= PQntuples(this->pgresult)) {
                rb_raise(rb_eArgError,"invalid tuple number %d", i);
        }
        if(j < 0 || j >= PQnfields(this->pgresult)) {
                rb_raise(rb_eArgError,"invalid field number %d", j);
        }
        return this->p_typemap->funcs.typecast_result_value(this->p_typemap, self, i, j);
}
inspect()

Return a String representation of the object suitable for debugging.

# File lib/pg/result.rb, line 31
def inspect
        str = self.to_s
        str[-1,0] = if cleared?
                " cleared"
        else
                " status=#{res_status(result_status)} ntuples=#{ntuples} nfields=#{nfields} cmd_tuples=#{cmd_tuples}"
        end
        return str
end
map_types!(type_map)

Apply a type map for all value retrieving methods.

type_map: a PG::TypeMap instance.

This method is equal to type_map= , but returns self, so that calls can be chained.

See also PG::BasicTypeMapForResults

# File lib/pg/result.rb, line 15
def map_types!(type_map)
        self.type_map = type_map
        return self
end
nfields() → Integer

Returns the number of columns in the query result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.nfields          # 3
res.num_fields       # 3

static VALUE
pgresult_nfields(VALUE self)
{
        return INT2NUM(PQnfields(pgresult_get(self)));
}
Also aliased as: num_fields
nparams() → Integer

Returns the number of parameters of a prepared statement. Only useful for the result returned by conn.describePrepared

static VALUE
pgresult_nparams(VALUE self)
{
        PGresult *result;

        result = pgresult_get(self);
        return INT2FIX(PQnparams(result));
}
ntuples() → Integer

Returns the number of tuples in the query result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.ntuples          # 1
res.num_tuples       # 1

static VALUE
pgresult_ntuples(VALUE self)
{
        return INT2FIX(PQntuples(pgresult_get(self)));
}
Also aliased as: num_tuples
num_fields()

Returns the number of columns in the query result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.nfields          # 3
res.num_fields       # 3
Alias for: nfields
num_tuples()

Returns the number of tuples in the query result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.ntuples          # 1
res.num_tuples       # 1
Alias for: ntuples
oid_value() → Integer

Returns the oid of the inserted row if applicable, otherwise nil.

static VALUE
pgresult_oid_value(VALUE self)
{
        Oid n = PQoidValue(pgresult_get(self));
        if (n == InvalidOid)
                return Qnil;
        else
                return UINT2NUM(n);
}
paramtype( param_number ) → Oid

Returns the Oid of the data type of parameter param_number. Only useful for the result returned by conn.describePrepared

static VALUE
pgresult_paramtype(VALUE self, VALUE param_number)
{
        PGresult *result;

        result = pgresult_get(self);
        return UINT2NUM(PQparamtype(result,NUM2INT(param_number)));
}
res_status → String
res_status( status ) → String

Returns the string representation of the status of the result or of the provided result_status.

static VALUE
pgresult_res_status(int argc, VALUE *argv, VALUE self)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        VALUE ret;

        if( argc == 0 ){
                ret = rb_str_new2(PQresStatus(PQresultStatus(this->pgresult)));
        }else if( argc == 1 ){
                ret = rb_str_new2(PQresStatus(NUM2INT(argv[0])));
        }else{
                rb_raise(rb_eArgError, "only 0 or 1 arguments expected");
        }
        PG_ENCODING_SET_NOCHECK(ret, this->enc_idx);
        return ret;
}
result_error_field(p1)

Returns the individual field of an error.

fieldcode is one of:

  • PG_DIAG_SEVERITY

  • PG_DIAG_SQLSTATE

  • PG_DIAG_MESSAGE_PRIMARY

  • PG_DIAG_MESSAGE_DETAIL

  • PG_DIAG_MESSAGE_HINT

  • PG_DIAG_STATEMENT_POSITION

  • PG_DIAG_INTERNAL_POSITION

  • PG_DIAG_INTERNAL_QUERY

  • PG_DIAG_CONTEXT

  • PG_DIAG_SOURCE_FILE

  • PG_DIAG_SOURCE_LINE

  • PG_DIAG_SOURCE_FUNCTION

An example:

begin
    conn.exec( "SELECT * FROM nonexistent_table" )
rescue PG::Error => err
    p [
        err.result.error_field( PG::Result::PG_DIAG_SEVERITY ),
        err.result.error_field( PG::Result::PG_DIAG_SQLSTATE ),
        err.result.error_field( PG::Result::PG_DIAG_MESSAGE_PRIMARY ),
        err.result.error_field( PG::Result::PG_DIAG_MESSAGE_DETAIL ),
        err.result.error_field( PG::Result::PG_DIAG_MESSAGE_HINT ),
        err.result.error_field( PG::Result::PG_DIAG_STATEMENT_POSITION ),
        err.result.error_field( PG::Result::PG_DIAG_INTERNAL_POSITION ),
        err.result.error_field( PG::Result::PG_DIAG_INTERNAL_QUERY ),
        err.result.error_field( PG::Result::PG_DIAG_CONTEXT ),
        err.result.error_field( PG::Result::PG_DIAG_SOURCE_FILE ),
        err.result.error_field( PG::Result::PG_DIAG_SOURCE_LINE ),
        err.result.error_field( PG::Result::PG_DIAG_SOURCE_FUNCTION ),
    ]
end

Outputs:

["ERROR", "42P01", "relation \"nonexistent_table\" does not exist", nil, nil,
 "15", nil, nil, nil, "path/to/parse_relation.c", "857", "parserOpenTable"]
Alias for: error_field
result_error_message()

Returns the error message of the command as a string.

Alias for: error_message
result_status() → Integer

Returns the status of the query. The status value is one of:

  • PGRES_EMPTY_QUERY

  • PGRES_COMMAND_OK

  • PGRES_TUPLES_OK

  • PGRES_COPY_OUT

  • PGRES_COPY_IN

  • PGRES_BAD_RESPONSE

  • PGRES_NONFATAL_ERROR

  • PGRES_FATAL_ERROR

  • PGRES_COPY_BOTH

  • PGRES_SINGLE_TUPLE

  • PGRES_TUPLES_CHUNK

  • PGRES_PIPELINE_SYNC

  • PGRES_PIPELINE_ABORTED

Use res_status or Result.res_status to retrieve the string representation.

static VALUE
pgresult_result_status(VALUE self)
{
        return INT2FIX(PQresultStatus(pgresult_get(self)));
}
result_verbose_error_message(p1, p2)

Returns a reformatted version of the error message associated with the PG::Result object.

Alias for: verbose_error_message
stream_each{ |tuple| ... }

Invokes block for each tuple in the result set in single row mode.

This is a convenience method for retrieving all result tuples as they are transferred. It is an alternative to repeated calls of PG::Connection#get_result , but given that it avoids the overhead of wrapping each row into a dedicated result object, it delivers data in nearly the same speed as with ordinary results.

The base result must be in status PGRES_SINGLE_TUPLE or PGRES_TUPLES_CHUNK. It iterates over all tuples until the status changes to PGRES_TUPLES_OK. A PG::Error is raised for any errors from the server.

Row description data does not change while the iteration. All value retrieval methods refer to only the current row. Result#ntuples returns 1 while the iteration and 0 after all tuples were yielded.

Example:

conn.send_query( "first SQL query; second SQL query" )
conn.set_single_row_mode
conn.get_result.stream_each do |row|
  # do something with each received row of the first query
end
conn.get_result.stream_each do |row|
  # do something with each received row of the second query
end
conn.get_result  # => nil   (no more results)

static VALUE
pgresult_stream_each(VALUE self)
{
        return pgresult_stream_any(self, yield_hash, NULL);
}
stream_each_row { |row| ... }

Yields each row of the result set in single row mode. The row is a list of column values.

This method works equally to stream_each , but yields an Array of values.

static VALUE
pgresult_stream_each_row(VALUE self)
{
        return pgresult_stream_any(self, yield_array, NULL);
}
stream_each_tuple { |tuple| ... }

Yields each row of the result set in single row mode.

This method works equally to stream_each , but yields a PG::Tuple object.

static VALUE
pgresult_stream_each_tuple(VALUE self)
{
        /* allocate VALUEs that are shared between all streamed tuples */
        ensure_init_for_tuple(self);

        return pgresult_stream_any(self, yield_tuple, NULL);
}
tuple( n ) → PG::Tuple

Returns a PG::Tuple from the nth row of the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.tuple(0)         # #<PG::Tuple a: "1", b: "2", c: nil>

static VALUE
pgresult_tuple(VALUE self, VALUE index)
{
        int tuple_num = NUM2INT( index );
        t_pg_result *this;
        int num_tuples;

        this = pgresult_get_this_safe(self);
        num_tuples = PQntuples(this->pgresult);

        if ( tuple_num < 0 || tuple_num >= num_tuples )
                rb_raise( rb_eIndexError, "Index %d is out of range", tuple_num );

        ensure_init_for_tuple(self);

  return pg_tuple_new(self, tuple_num);
}
tuple_values( n ) → array

Returns an Array of the field values from the nth row of the result.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.tuple_values(0)  # ["1", "2", nil]

static VALUE
pgresult_tuple_values(VALUE self, VALUE index)
{
        int tuple_num = NUM2INT( index );
        t_pg_result *this;
        int field;
        int num_tuples;
        int num_fields;

        this = pgresult_get_this_safe(self);
        num_tuples = PQntuples(this->pgresult);
        num_fields = PQnfields(this->pgresult);

        if ( tuple_num < 0 || tuple_num >= num_tuples )
                rb_raise( rb_eIndexError, "Index %d is out of range", tuple_num );

        {
                PG_VARIABLE_LENGTH_ARRAY(VALUE, row_values, num_fields, PG_MAX_COLUMNS)

                /* populate the row */
                for ( field = 0; field < num_fields; field++ ) {
                        row_values[field] = this->p_typemap->funcs.typecast_result_value(this->p_typemap, self, tuple_num, field);
                }
                return rb_ary_new4( num_fields, row_values );
        }
}
type_map → value

Returns the PG::TypeMap that is currently set for type casts of result values to ruby objects. The default is retrieved from PG::Connection#type_map_for_results , which defaults to PG::TypeMapAllStrings .

static VALUE
pgresult_type_map_get(VALUE self)
{
        t_pg_result *this = pgresult_get_this(self);

        return this->typemap;
}
type_map = typemap

Set the PG::TypeMap that is used for type casts of result values to ruby objects.

All value retrieval methods will respect the type map and will do the type casts from PostgreSQL’s wire format to Ruby objects on the fly, according to the rules and decoders defined in the given typemap.

typemap must be a kind of PG::TypeMap .

See also map_types! and PG::BasicTypeMapForResults

static VALUE
pgresult_type_map_set(VALUE self, VALUE typemap)
{
        t_pg_result *this = pgresult_get_this(self);
        t_typemap *p_typemap;

        rb_check_frozen(self);
        /* Check type of method param */
        TypedData_Get_Struct(typemap, t_typemap, &pg_typemap_type, p_typemap);

        typemap = p_typemap->funcs.fit_to_result( typemap, self );
        RB_OBJ_WRITE(self, &this->typemap, typemap);
        this->p_typemap = RTYPEDDATA_DATA( typemap );

        return typemap;
}
values → Array

Returns all tuples as an array of arrays.

res = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
res.values           # [["1", "2", nil]]

static VALUE
pgresult_values(VALUE self)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        int row;
        int field;
        int num_rows = PQntuples(this->pgresult);
        int num_fields = PQnfields(this->pgresult);
        VALUE results = rb_ary_new2( num_rows );

        for ( row = 0; row < num_rows; row++ ) {
                PG_VARIABLE_LENGTH_ARRAY(VALUE, row_values, num_fields, PG_MAX_COLUMNS)

                /* populate the row */
                for ( field = 0; field < num_fields; field++ ) {
                        row_values[field] = this->p_typemap->funcs.typecast_result_value(this->p_typemap, self, row, field);
                }
                rb_ary_store( results, row, rb_ary_new4( num_fields, row_values ) );
        }

        return results;
}
verbose_error_message( verbosity, show_context ) → String

Returns a reformatted version of the error message associated with the PG::Result object.

static VALUE
pgresult_verbose_error_message(VALUE self, VALUE verbosity, VALUE show_context)
{
        t_pg_result *this = pgresult_get_this_safe(self);
        VALUE ret;
        char *c_str;

        c_str = PQresultVerboseErrorMessage(this->pgresult, NUM2INT(verbosity), NUM2INT(show_context));
        if(!c_str)
                rb_raise(rb_eNoMemError, "insufficient memory to format error message");

        ret = rb_str_new2(c_str);
        PQfreemem(c_str);
        PG_ENCODING_SET_NOCHECK(ret, this->enc_idx);

        return ret;
}
Also aliased as: result_verbose_error_message