$mysqli->escape_string - can it be used without specifying exact field name - php

Question

I have code that generalizes building the SQL string to insert a record into a table by (1) setting the 'name' of the form element to be the same as the table column to which it corresponds, and (2) building an array of field name => value pairs. I do it like this:
$fldArray = array();
foreach($_POST as $field => $value) {
$fldArray[$field] = $value; //create a field => value array
}
This allows me to build the SQL statement easily like this:
$visit_SQL = "INSERT INTO visits (";
foreach ($fldArray as $key => $value) {
$flds .= ($key) . ", " ; // sets up all the field names.
I then do something similar to generate the 'VALUES' part of the SQL statement. I then need only to add the provider_id info
$visit_SQL = $visit_SQL . "provider_id, " . $flds . ") VALUES (" . $user_ID . ", " . $vals . ")";
The reason I go about it this way is that there are a large number of Yes/No checkboxes on the form so it saves typing errors etc.
This works well except for two text inputs that require "$mysqli->escape_string(['field_name']) to deal with apostrophes etc. before inserting into the database.
I proved that the following works for explicit field names,
$test = $mysqli->escape_string($_POST['visit_notes']);
print_r($test) ;
However, I cannot generalize it into this statement (from above):
foreach($_POST as $field => $mysqli->escape_string($_POST[$value])) {
$fldArray[$field] = $value;
}
I'd appreciate knowing if I have a syntax error or if what I'm seeking is not possible.
Thanks in advance for any helpful responses.

Answer 1

You don't put the function call in the foreach header, you do it in the body.
foreach($_POST as $field => $value) {
$fldArray[$field] = $mysqli->escape_string($value);
}