class PG::Result - pg-0.21.0 Documentation

# class PG::Result

The class to represent the query result tuples (rows). An instance of this class is created as the result of every query. You may need to invoke the clear method of the instance when finished with the result for better memory performance.

Example:

    require 'pg'
    conn = PG.connect(:dbname => 'test')
    res  = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')
    res.getvalue(0,0) # '1'
    res[0]['b']       # '2'
    res[0]['c']       # nil

### Public Instance Methods

res[ n ] → Hash click to toggle source

Returns tuple n as a hash.

    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 );

            /* We reuse the Hash of the previous output for larger row counts.
             * This is somewhat faster than populating an empty Hash object. */
            tuple = NIL_P(this->tuple_hash) ? rb_hash_new() : this->tuple_hash;
            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 );
            }
            /* Store a copy of the filled hash for use at the next row. */
            if( num_tuples > 10 )
                    this->tuple_hash = rb_hash_dup(tuple);

            return tuple;
    }

autoclear? → boolean click to toggle source

Returns `true` if the underlying C struct will be cleared automatically by libpq. Elsewise the result is cleared by #clear or by the GC when it's no longer in use.

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

check → nil click to toggle source

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

    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:
    #ifdef HAVE_CONST_PGRES_COPY_BOTH
                    case PGRES_COPY_BOTH:
    #endif
    #ifdef HAVE_CONST_PGRES_SINGLE_TUPLE
                    case PGRES_SINGLE_TUPLE:
    #endif
                    case PGRES_EMPTY_QUERY:
                    case PGRES_COMMAND_OK:
                            return self;
                    case PGRES_BAD_RESPONSE:
                    case PGRES_FATAL_ERROR:
                    case PGRES_NONFATAL_ERROR:
                            error = rb_str_new2( PQresultErrorMessage(this->pgresult) );
                            break;
                    default:
                            error = rb_str_new2( "internal error : unknown result status." );
                    }
            }

            PG_ENCODING_SET_NOCHECK( error, ENCODING_GET(self) );

            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()
Alias for: check
clear() → nil click to toggle source

Clears the PG::Result object as the result of the query.

If #autoclear? is true then the result is marked as cleared and the underlying C struct will be cleared automatically by libpq.

    VALUE
    pg_result_clear(VALUE self)
    {
            t_pg_result *this = pgresult_get_this(self);
            if( !this->autoclear )
                    PQclear(pgresult_get(self));
            this->pgresult = NULL;
            return Qnil;
    }

cleared? → boolean click to toggle source

Returns `true` if the backend result memory has been free'd.

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

cmd_status() → String click to toggle source

Returns the status string of the last query command.

    static VALUE
    pgresult_cmd_status(VALUE self)
    {
            VALUE ret = rb_tainted_str_new2(PQcmdStatus(pgresult_get(self)));
            PG_ENCODING_SET_NOCHECK(ret, ENCODING_GET(self));
            return ret;
    }

cmd_tuples() → Integer click to toggle source

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 INT2NUM(n);
    }

Also aliased as: cmdtuples
cmdtuples()
Alias for: cmd_tuples
column_values( n ) → array click to toggle source

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

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

each{ |tuple| ... } click to toggle source

Invokes block for each tuple in the result set.

    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| ... } click to toggle source

Yields each row of the result. The row is a list of column values.

    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 click to toggle source

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 nonexistant_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 \"nonexistant_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)
    {
            PGresult *result = pgresult_get( self );
            int fieldcode = NUM2INT( field );
            char * fieldstr = PQresultErrorField( result, fieldcode );
            VALUE ret = Qnil;

            if ( fieldstr ) {
                    ret = rb_tainted_str_new2( fieldstr );
                    PG_ENCODING_SET_NOCHECK( ret, ENCODING_GET(self ));
            }

            return ret;
    }

Also aliased as: result_error_field
error_message() → String click to toggle source

Returns the error message of the command as a string.

    static VALUE
    pgresult_error_message(VALUE self)
    {
            VALUE ret = rb_tainted_str_new2(PQresultErrorMessage(pgresult_get(self)));
            PG_ENCODING_SET_NOCHECK(ret, ENCODING_GET(self));
            return ret;
    }

Also aliased as: result_error_message
fformat( column_number ) → Integer click to toggle source

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_values( field ) → array click to toggle source

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

    static VALUE
    pgresult_field_values( VALUE self, VALUE field )
    {
            PGresult *result = pgresult_get( self );
            const char *fieldname = StringValueCStr( field );
            int 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 click to toggle source

Returns an array of Strings representing the names of the fields in the result.

    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 ) click to toggle source

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 click to toggle source

Returns the name of the column corresponding to index.

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

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

            fname = rb_tainted_str_new2(PQfname(result, i));
            PG_ENCODING_SET_NOCHECK(fname, ENCODING_GET(self));
            return rb_obj_freeze(fname);
    }

fnumber( name ) → Integer click to toggle source

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( %Q{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( %Q{"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);
    }

fsize( index ) click to toggle source

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 click to toggle source

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 click to toggle source

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 click to toggle source

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 click to toggle source

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 click to toggle source

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 ) click to toggle source

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() click to toggle source

Return a String representation of the object suitable for debugging.

    # File lib/pg/result.rb, line 20
    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) click to toggle source

Apply a type map for all value retrieving methods.

`type_map`: a PG::TypeMap instance.

See PG::BasicTypeMapForResults

    # File lib/pg/result.rb, line 13
    def map_types!(type_map)
            self.type_map = type_map
            return self
    end

nfields() → Integer click to toggle source

Returns the number of columns in the query result.

    static VALUE
    pgresult_nfields(VALUE self)
    {
            return INT2NUM(PQnfields(pgresult_get(self)));
    }

Also aliased as: num_fields
nparams() → Integer click to toggle source

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 click to toggle source

Returns the number of tuples in the query result.

    static VALUE
    pgresult_ntuples(VALUE self)
    {
            return INT2FIX(PQntuples(pgresult_get(self)));
    }

Also aliased as: num_tuples
num_fields()
Alias for: nfields
num_tuples()
Alias for: ntuples
oid_value() → Integer click to toggle source

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 click to toggle source

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( status ) → String click to toggle source

Returns the string representation of status `status`.

    static VALUE
    pgresult_res_status(VALUE self, VALUE status)
    {
            VALUE ret = rb_tainted_str_new2(PQresStatus(NUM2INT(status)));
            PG_ENCODING_SET_NOCHECK(ret, ENCODING_GET(self));
            return ret;
    }

result_error_field(p1)
Alias for: error_field
result_error_message()
Alias for: error_message
result_status() → Integer click to toggle source

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`

    static VALUE
    pgresult_result_status(VALUE self)
    {
            return INT2FIX(PQresultStatus(pgresult_get(self)));
    }

stream_each{ |tuple| ... } click to toggle source

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 result must be in status PGRES_SINGLE_TUPLE. 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. #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 the received row of the first query
    end
    conn.get_result.stream_each do |row|
      # do something with the received row of the second query
    end
    conn.get_result  # => nil   (no more results)

    static VALUE
    pgresult_stream_each(VALUE self)
    {
            t_pg_result *this;
            int nfields;
            PGconn *pgconn;
            PGresult *pgresult;

            RETURN_ENUMERATOR(self, 0, NULL);

            this = pgresult_get_this_safe(self);
            pgconn = pg_get_pgconn(this->connection);
            pgresult = this->pgresult;
            nfields = PQnfields(pgresult);

            for(;;){
                    int tuple_num;
                    int ntuples = PQntuples(pgresult);

                    switch( PQresultStatus(pgresult) ){
                            case PGRES_TUPLES_OK:
                                    if( ntuples == 0 )
                                            return self;
                                    rb_raise( rb_eInvalidResultStatus, "PG::Result is not in single row mode");
                            case PGRES_SINGLE_TUPLE:
                                    break;
                            default:
                                    pg_result_check( self );
                    }

                    for(tuple_num = 0; tuple_num < ntuples; tuple_num++) {
                            rb_yield(pgresult_aref(self, INT2NUM(tuple_num)));
                    }

                    if( !this->autoclear ){
                            PQclear( pgresult );
                            this->pgresult = NULL;
                    }

                    pgresult = gvl_PQgetResult(pgconn);
                    if( pgresult == NULL )
                            rb_raise( rb_eNoResultError, "no result received - possibly an intersection with another result retrieval");

                    if( nfields != PQnfields(pgresult) )
                            rb_raise( rb_eInvalidChangeOfResultFields, "number of fields must not change in single row mode");

                    this->pgresult = pgresult;
            }

            /* never reached */
            return self;
    }

stream_each_row { |row| ... } click to toggle source

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)
    {
            t_pg_result *this;
            int row;
            int nfields;
            PGconn *pgconn;
            PGresult *pgresult;

            RETURN_ENUMERATOR(self, 0, NULL);

            this = pgresult_get_this_safe(self);
            pgconn = pg_get_pgconn(this->connection);
            pgresult = this->pgresult;
            nfields = PQnfields(pgresult);

            for(;;){
                    int ntuples = PQntuples(pgresult);

                    switch( PQresultStatus(pgresult) ){
                            case PGRES_TUPLES_OK:
                                    if( ntuples == 0 )
                                            return self;
                                    rb_raise( rb_eInvalidResultStatus, "PG::Result is not in single row mode");
                            case PGRES_SINGLE_TUPLE:
                                    break;
                            default:
                                    pg_result_check( self );
                    }

                    for ( row = 0; row < ntuples; row++ ) {
                            PG_VARIABLE_LENGTH_ARRAY(VALUE, row_values, nfields, PG_MAX_COLUMNS)
                            int field;

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

                    if( !this->autoclear ){
                            PQclear( pgresult );
                            this->pgresult = NULL;
                    }

                    pgresult = gvl_PQgetResult(pgconn);
                    if( pgresult == NULL )
                            rb_raise( rb_eNoResultError, "no result received - possibly an intersection with another result retrieval");

                    if( nfields != PQnfields(pgresult) )
                            rb_raise( rb_eInvalidChangeOfResultFields, "number of fields must not change in single row mode");

                    this->pgresult = pgresult;
            }

            /* never reached */
            return self;
    }

type_map → value click to toggle source

Returns the TypeMap that is currently set for type casts of result values to ruby objects.

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

            return this->typemap;
    }

type_map = typemap click to toggle source

Set the 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 .

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

            if ( !rb_obj_is_kind_of(typemap, rb_cTypeMap) ) {
                    rb_raise( rb_eTypeError, "wrong argument type %s (expected kind of PG::TypeMap)",
                                    rb_obj_classname( typemap ) );
            }
            Data_Get_Struct(typemap, t_typemap, p_typemap);

            this->typemap = p_typemap->funcs.fit_to_result( typemap, self );
            this->p_typemap = DATA_PTR( this->typemap );

            return typemap;
    }

values → Array click to toggle source

Returns all tuples as an array of arrays.

    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;
    }