pg_fetch_object
(PHP 4, PHP 5)
pg_fetch_object — Fetch a row as an object
Описание
pg_fetch_object() returns an object with properties that correspond to the fetched row's field names. It can optionally instantiate an object of a specific class, and pass parameters to that class's constructor.
Замечание: Эта функция устанавливает NULL-поля в значение NULL PHP.
Speed-wise, the function is identical to pg_fetch_array(), and almost as fast as pg_fetch_row() (the difference is insignificant).
Список параметров
- result
-
PostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).
- row
-
Row number in result to fetch. Rows are numbered from 0 upwards. If omitted, next row is fetched.
- result_type
-
Ignored and deprecated. Defaults to PGSQL_ASSOC.
- class_name
-
The name of the class to instantiate, set the properties of and return. If not specified, a stdClass object is returned.
- params
-
An optional array of parameters to pass to the constructor for class_name objects.
Возвращаемые значения
An object with one attribute for each field name in the result. Database NULL values are returned as NULL.
FALSE is returned if row exceeds the number of rows in the set, there are no more rows, or on any other error.
Список изменений
| Версия | Описание |
|---|---|
| 5.0.0 | class_name and params were added. The old form with result_type still exists for backwards compatibility. |
| 4.3.0 | result_type default changed from PGSQL_BOTH to PGSQL_ASSOC, since the numeric index was illegal. |
| 4.1.0 | The parameter row became optional. |
Примеры
Пример #1 pg_fetch_object() example
<?php
$database = "store";
$db_conn = pg_connect("host=localhost port=5432 dbname=$database");
if (!$db_conn) {
echo "Failed connecting to postgres database $database\n";
exit;
}
$qu = pg_query($db_conn, "SELECT * FROM books ORDER BY author");
while ($data = pg_fetch_object($qu)) {
echo $data->author . " (";
echo $data->year . "): ";
echo $data->title . "<br />";
}
pg_free_result($qu);
pg_close($db_conn);
?>
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Коментарии
The result_type arg is either invalid or incorrectly documented, since the "result_type is optional..." paragraph is copied verbatim from pg_fetch_array, and the PGSQL_NUM option is in conflict with the preceding paragraph's, "you can only access the data by the field names, and not by theiroffsets."
This isn't all that useful. If you do, for example, foreach($row as $field) then you still get every value twice!
You can do something like this, though:
foreach ($line as $key => $cell){
if (! is_numeric($key)){
echo "<td>$key $cell</td>";
}
}
is is_numeric strict enough?
When you retrieve the contents of a "timestamp with timezone" field, this will set the environment's timezone variables. Therefore, this is dangerous:
$s=$row->mydatefield;
$unixtimestamp=postgresqltimestamp2unix($s);
echo date("Y-m-d H:i:s",$unixtimestamp);
Here, postgresqltimestamp2unix is a function that converts the postgresql timestamp to Unix. The retrieval of the field data in the first line of the example above will influence the timezone used in date() in the third line.
Something I have learned to use:
$result=$pg_query (...);
$num = pg_numrows($result);
for($count=0;$count < $num && $data=pg_fetch_object($result,$count);$count++)
{
printf("<tr>\n");
printf(" <td>%s</td>\n",$data->foo);
printf(" <td>%s</td>\n",$data->bar);
printf("</tr>\n");
}
If you're wanting to use objects for your results, but are put off because you can't seem to apply a function to each field of the result (like stripslashes for example), try this code:
<?php
// Code to connect, do query etc etc...
$row = pg_fetch_object($result);
$vars = get_object_vars($row);
foreach ( $vars as $key => $var )
{
$row->{$key} = stripslashes($var);
}
?>
I noticed that many people use FOR loops to extract query data. This is the method I use to extract data.
<?php
@$members = pg_query($db_conn, 'SELECT id,name FROM boards.members ORDER BY name;');
if ($members AND pg_num_rows($members)) {
while ($member = pg_fetch_object($members)) {
echo $member->name.' ('.$member->id.')';
}
}
?>
If an error occurs (or nothing is returned) in the above code nothing will output. An ELSE clause can be added to the IF to handle query errors (or nothing being returned). Or a seperate check can be performed for the event that nothing is returned by using an ELSEIF clause.
I like this method because it doesn't use any temporary counter variables.
PostgreSQL boolean true becomes string "t"PostgreSQL boolean false becomes string "f"
This is ambiguous, and leads to code duplication. I wonder why aren't the types correctly typed when fetching values. We could at least have an optional parameter to enable that.
Getting db results as object.
<?php
$qry = pg_query("SELECT * FROM users");
$rows = array();
while ($fch = pg_fetch_object($qry)) {
$rows[] = $fch;
}
// or
$rows = array_map(function($a){
return (object) $a;
}, (array) pg_fetch_all($qry));
?>