Class | PGresult |
In: |
ext/pg.c
|
Parent: | Object |
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 = PGconn.open(: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
PGRES_EMPTY_QUERY | = | #result_status constant | The string sent to the server was empty. | |
PGRES_COMMAND_OK | = | #result_status constant | Successful completion of a command returning no data. | |
PGRES_TUPLES_OK | = | #result_status constant | Successful completion of a command returning data (such as a SELECT or SHOW). | |
PGRES_COPY_OUT | = | #result_status constant | Copy Out (from server) data transfer started. | |
PGRES_COPY_IN | = | #result_status constant | Copy In (to server) data transfer started. | |
PGRES_BAD_RESPONSE | = | #result_status constant | The server’s response was not understood. | |
PGRES_NONFATAL_ERROR | = | #result_status constant | A nonfatal error (a notice or warning) occurred. | |
PGRES_FATAL_ERROR | = | #result_status constant | A fatal error occurred. | |
PG_DIAG_SEVERITY | = | #result_error_field argument constant | The severity; the field contents are ERROR, FATAL, or PANIC (in an error message), or WARNING, NOTICE, DEBUG, INFO, or LOG (in a notice message), or a localized translation of one of these. Always present. | |
PG_DIAG_SQLSTATE | = | #result_error_field argument constant | The SQLSTATE code for the error. The SQLSTATE code identies the type of error that has occurred; it can be used by front-end applications to perform specic operations (such as er- ror handling) in response to a particular database error. For a list of the possible SQLSTATE codes, see Appendix A. This eld is not localizable, and is always present. | |
PG_DIAG_MESSAGE_PRIMARY | = | #result_error_field argument constant | The primary human-readable error message (typically one line). Always present. | |
PG_DIAG_MESSAGE_DETAIL | = | #result_error_field argument constant: Detail | an optional secondary error message carrying more detail about the problem. Might run to multiple lines. | |
PG_DIAG_MESSAGE_HINT | = | #result_error_field argument constant: Hint | an optional suggestion what to do about the problem. This is intended to differ from detail in that it offers advice (potentially inappropriate) rather than hard facts. Might run to multiple lines. | |
PG_DIAG_STATEMENT_POSITION | = | #result_error_field argument constant | A string containing a decimal integer indicating an error cursor position as an index into the original statement string. The rst character has index 1, and positions are measured in characters not bytes. | |
PG_DIAG_INTERNAL_POSITION | = | #result_error_field argument constant | This is dened the same as the PG_DIAG_STATEMENT_POSITION eld, but it is used when the cursor position refers to an internally generated command rather than the one submitted by the client. The PG_DIAG_INTERNAL_QUERY eld will always appear when this eld appears. | |
PG_DIAG_INTERNAL_QUERY | = | #result_error_field argument constant | The text of a failed internally-generated command. This could be, for example, a SQL query issued by a PL/pgSQL function. | |
PG_DIAG_CONTEXT | = | #result_error_field argument constant | An indication of the context in which the error occurred. Presently this includes a call stack traceback of active procedural language functions and internally-generated queries. The trace is one entry per line, most recent rst. | |
PG_DIAG_SOURCE_FILE | = | #result_error_field argument constant | The le name of the source-code location where the error was reported. | |
PG_DIAG_SOURCE_LINE | = | #result_error_field argument constant | The line number of the source-code location where the error was reported. | |
PG_DIAG_SOURCE_FUNCTION | = | #result_error_field argument constant | The name of the source-code function reporting the error. | |
InvalidOid | = | INT2FIX(InvalidOid) | Invalid OID constant |
Returns tuple n as a hash.
/* * call-seq: * res[ n ] -> Hash * * Returns tuple _n_ as a hash. */ static VALUE pgresult_aref(VALUE self, VALUE index) { PGresult *result = get_pgresult(self); int tuple_num = NUM2INT(index); int field_num; VALUE fname,val; VALUE tuple; if ( tuple_num < 0 || tuple_num >= PQntuples(result) ) rb_raise( rb_eIndexError, "Index %d is out of range", tuple_num ); tuple = rb_hash_new(); for ( field_num = 0; field_num < PQnfields(result); field_num++ ) { fname = rb_tainted_str_new2( PQfname(result,field_num) ); ASSOCIATE_INDEX(fname, self); if ( PQgetisnull(result, tuple_num, field_num) ) { rb_hash_aset( tuple, fname, Qnil ); } else { val = rb_tainted_str_new( PQgetvalue(result, tuple_num, field_num ), PQgetlength(result, tuple_num, field_num) ); /* associate client encoding for text format only */ if ( 0 == PQfformat(result, field_num) ) { ASSOCIATE_INDEX( val, self ); } else { #ifdef M17N_SUPPORTED rb_enc_associate( val, rb_ascii8bit_encoding() ); #endif } rb_hash_aset( tuple, fname, val ); } } return tuple; }
Returns the status string of the last query command.
/* * call-seq: * res.cmd_status() -> String * * Returns the status string of the last query command. */ static VALUE pgresult_cmd_status(VALUE self) { VALUE ret = rb_tainted_str_new2(PQcmdStatus(get_pgresult(self))); ASSOCIATE_INDEX(ret, self); return ret; }
Returns the number of tuples (rows) affected by the SQL command.
If the SQL command that generated the PGresult was not one of:
or if no tuples were affected, 0 is returned.
/* * call-seq: * res.cmd_tuples() -> Fixnum * * Returns the number of tuples (rows) affected by the SQL command. * * If the SQL command that generated the PGresult was not one of: * * +INSERT+ * * +UPDATE+ * * +DELETE+ * * +MOVE+ * * +FETCH+ * or if no tuples were affected, <tt>0</tt> is returned. */ static VALUE pgresult_cmd_tuples(VALUE self) { long n; n = strtol(PQcmdTuples(get_pgresult(self)),NULL, 10); return INT2NUM(n); }
Returns an Array of the values from the nth column of each tuple in the result.
/* * call-seq: * res.column_values( n ) -> array * * 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 ); }
Invokes block for each tuple in the result set.
/* * call-seq: * res.each{ |tuple| ... } * * Invokes block for each tuple in the result set. */ static VALUE pgresult_each(VALUE self) { PGresult *result = get_pgresult(self); int tuple_num; for(tuple_num = 0; tuple_num < PQntuples(result); tuple_num++) { rb_yield(pgresult_aref(self, INT2NUM(tuple_num))); } return self; }
Returns the individual field of an error.
fieldcode is one of:
An example:
begin conn.exec( "SELECT * FROM nonexistant_table" ) rescue PGError => err p [ result.error_field( PGresult::PG_DIAG_SEVERITY ), result.error_field( PGresult::PG_DIAG_SQLSTATE ), result.error_field( PGresult::PG_DIAG_MESSAGE_PRIMARY ), result.error_field( PGresult::PG_DIAG_MESSAGE_DETAIL ), result.error_field( PGresult::PG_DIAG_MESSAGE_HINT ), result.error_field( PGresult::PG_DIAG_STATEMENT_POSITION ), result.error_field( PGresult::PG_DIAG_INTERNAL_POSITION ), result.error_field( PGresult::PG_DIAG_INTERNAL_QUERY ), result.error_field( PGresult::PG_DIAG_CONTEXT ), result.error_field( PGresult::PG_DIAG_SOURCE_FILE ), result.error_field( PGresult::PG_DIAG_SOURCE_LINE ), result.error_field( PGresult::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"]
/* * call-seq: * res.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 nonexistant_table" ) * rescue PGError => err * p [ * result.error_field( PGresult::PG_DIAG_SEVERITY ), * result.error_field( PGresult::PG_DIAG_SQLSTATE ), * result.error_field( PGresult::PG_DIAG_MESSAGE_PRIMARY ), * result.error_field( PGresult::PG_DIAG_MESSAGE_DETAIL ), * result.error_field( PGresult::PG_DIAG_MESSAGE_HINT ), * result.error_field( PGresult::PG_DIAG_STATEMENT_POSITION ), * result.error_field( PGresult::PG_DIAG_INTERNAL_POSITION ), * result.error_field( PGresult::PG_DIAG_INTERNAL_QUERY ), * result.error_field( PGresult::PG_DIAG_CONTEXT ), * result.error_field( PGresult::PG_DIAG_SOURCE_FILE ), * result.error_field( PGresult::PG_DIAG_SOURCE_LINE ), * result.error_field( PGresult::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 = get_pgresult( self ); int fieldcode = NUM2INT( field ); char * fieldstr = PQresultErrorField( result, fieldcode ); VALUE ret = Qnil; if ( fieldstr ) { ret = rb_tainted_str_new2( fieldstr ); ASSOCIATE_INDEX( ret, self ); } return ret; }
Returns the error message of the command as a string.
/* * call-seq: * res.error_message() -> String * * Returns the error message of the command as a string. */ static VALUE pgresult_error_message(VALUE self) { VALUE ret = rb_tainted_str_new2(PQresultErrorMessage(get_pgresult(self))); ASSOCIATE_INDEX(ret, self); return ret; }
Returns the format (0 for text, 1 for binary) of column column_number.
Raises ArgumentError if column_number is out of range.
/* * call-seq: * res.fformat( column_number ) -> Fixnum * * 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 = get_pgresult(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)); }
Returns an Array of the values from the given field of each tuple in the result.
/* * call-seq: * res.field_values( field ) -> array * * 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 = get_pgresult( self ); const char *fieldname = RSTRING_PTR( 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 ); }
Returns an array of Strings representing the names of the fields in the result.
/* * call-seq: * res.fields() -> Array * * Returns an array of Strings representing the names of the fields in the result. */ static VALUE pgresult_fields(VALUE self) { PGresult *result; VALUE ary; int n, i; result = get_pgresult(self); n = PQnfields(result); ary = rb_ary_new2(n); for (i=0;i<n;i++) { VALUE val = rb_tainted_str_new2(PQfname(result, i)); ASSOCIATE_INDEX(val, self); rb_ary_push(ary, val); } return ary; }
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.
/* * call-seq: * res.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 = get_pgresult(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); }
Returns the name of the column corresponding to index.
/* * call-seq: * res.fname( index ) -> String * * Returns the name of the column corresponding to _index_. */ static VALUE pgresult_fname(VALUE self, VALUE index) { VALUE fname; PGresult *result; int i = NUM2INT(index); result = get_pgresult(self); if (i < 0 || i >= PQnfields(result)) { rb_raise(rb_eArgError,"invalid field number %d", i); } fname = rb_tainted_str_new2(PQfname(result, i)); ASSOCIATE_INDEX(fname, self); return fname; }
Returns the index of the field specified by the string name.
Raises an ArgumentError if the specified name isn‘t one of the field names; raises a TypeError if name is not a String.
/* * call-seq: * res.fnumber( name ) -> Fixnum * * Returns the index of the field specified by the string _name_. * * 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(get_pgresult(self), StringValuePtr(name)); if (n == -1) { rb_raise(rb_eArgError,"Unknown field: %s", StringValuePtr(name)); } return INT2FIX(n); }
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
/* * call-seq: * res.fsize( index ) * * Returns the size of the field type in bytes. Returns <tt>-1</tt> 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 = get_pgresult(self); if (i < 0 || i >= PQnfields(result)) { rb_raise(rb_eArgError,"invalid field number %d", i); } return INT2NUM(PQfsize(result, i)); }
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.
/* * call-seq: * res.ftable( column_number ) -> Fixnum * * 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 = get_pgresult(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 INT2FIX(n); }
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.
/* * call-seq: * res.ftablecol( column_number ) -> Fixnum * * 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 = get_pgresult(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); }
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.
/* * call-seq: * res.ftype( column_number ) * * 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 = get_pgresult(self); int i = NUM2INT(index); if (i < 0 || i >= PQnfields(result)) { rb_raise(rb_eArgError, "invalid field number %d", i); } return INT2NUM(PQftype(result, i)); }
Returns true if the specified value is nil; false otherwise.
/* * call-seq: * res.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 = get_pgresult(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; }
Returns the (String) length of the field in bytes.
Equivalent to res.value(tup_num,field_num).length.
/* * call-seq: * res.getlength( tup_num, field_num ) -> Fixnum * * Returns the (String) length of the field in bytes. * * Equivalent to <tt>res.value(<i>tup_num</i>,<i>field_num</i>).length</tt>. */ 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 = get_pgresult(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)); }
Returns the value in tuple number tup_num, field field_num, or nil if the field is NULL.
/* * call-seq: * res.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) { VALUE ret; PGresult *result; int i = NUM2INT(tup_num); int j = NUM2INT(field_num); result = get_pgresult(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); } if(PQgetisnull(result, i, j)) return Qnil; ret = rb_tainted_str_new(PQgetvalue(result, i, j), PQgetlength(result, i, j)); ASSOCIATE_INDEX(ret, self); return ret; }
Returns the number of columns in the query result.
/* * call-seq: * res.nfields() -> Fixnum * * Returns the number of columns in the query result. */ static VALUE pgresult_nfields(VALUE self) { return INT2NUM(PQnfields(get_pgresult(self))); }
Returns the number of parameters of a prepared statement. Only useful for the result returned by conn.describePrepared
/* * call-seq: * res.nparams() -> Fixnum * * 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 = get_pgresult(self); return INT2FIX(PQnparams(result)); }
Returns the number of tuples in the query result.
/* * call-seq: * res.ntuples() -> Fixnum * * Returns the number of tuples in the query result. */ static VALUE pgresult_ntuples(VALUE self) { return INT2FIX(PQntuples(get_pgresult(self))); }
Returns the oid of the inserted row if applicable, otherwise nil.
/* * call-seq: * res.oid_value() -> Fixnum * * Returns the +oid+ of the inserted row if applicable, * otherwise +nil+. */ static VALUE pgresult_oid_value(VALUE self) { Oid n = PQoidValue(get_pgresult(self)); if (n == InvalidOid) return Qnil; else return INT2FIX(n); }
Returns the Oid of the data type of parameter param_number. Only useful for the result returned by conn.describePrepared
/* * call-seq: * res.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 = get_pgresult(self); return INT2FIX(PQparamtype(result,NUM2INT(param_number))); }
Returns the string representation of status status.
/* * call-seq: * res.res_status( status ) -> String * * 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))); ASSOCIATE_INDEX(ret, self); return ret; }
Returns the status of the query. The status value is one of:
/* * call-seq: * res.result_status() -> Fixnum * * 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+ */ static VALUE pgresult_result_status(VALUE self) { return INT2FIX(PQresultStatus(get_pgresult(self))); }
Returns all tuples as an array of arrays.
/* * call-seq: * res.values -> Array * * Returns all tuples as an array of arrays. */ static VALUE pgresult_values(VALUE self, VALUE index) { PGresult* result = (PGresult*) get_pgresult(self); int row; int field; int num_rows = PQntuples(result); int num_fields = PQnfields(result); VALUE ary = rb_ary_new2(num_rows); for ( row = 0; row < num_rows; row++ ) { /* create new row */ VALUE new_row = rb_ary_new2(num_fields); /* add to return array */ rb_ary_store( ary, row, new_row ); /* populate it */ for ( field = 0; field < num_fields; field++ ) { if ( PQgetisnull(result, row, field) ) { rb_ary_store( new_row, field, Qnil ); } else { VALUE val = rb_tainted_str_new( PQgetvalue(result, row, field), PQgetlength(result, row, field) ); /* associate client encoding for text format only */ if ( 0 == PQfformat(result, field) ) { ASSOCIATE_INDEX( val, self ); } else { #ifdef M17N_SUPPORTED rb_enc_associate( val, rb_ascii8bit_encoding() ); #endif } rb_ary_store( new_row, field, val ); } } } return ary; }