Adding and updating Mysql child table with multiple number of entries - php

Question

I have two tables in mysql: a master table called "grants" and a child table called "goals". Grants has an id field as well as a bunch of others and goals has a goal name and a grant_id to link it to the grants table.
On the html form, the user can add or edit as many goals as they wish (I'm using Javascript to add new inputs). The form also gets any previous goals added and adds them to the form.
<div id="goals">
<?php
$goals = getGoalsById($_GET['id']);
if (empty($goals)) echo "<p>Goal 1: <input type='text' size='40' name='goals[]' /></p>";
else {
$i = 1;
foreach($goals as $goal) {
echo "<p>Goal {$i}: <input type='text' size='40' name=\"goals[{$goal['id']}]\" value=\"{$goal['goal']}\" /></p>";
$i++;
}
}
?>
</div>
<input type="button" value="Add goal" onClick="addInput('goals')" />
When I submit the form, I have the following statement to insert or update the goals:
foreach($goals as $key=>$goal) {
$sql_goals_add[] = "INSERT INTO goals (id, goal, grant_id) VALUES ($key,:goalnew,$grant_id) ON DUPLICATE KEY UPDATE goal = :goalupdate";
foreach ($sql_goals_add AS $sql_goal) {
$stmt_goal = $DBH->prepare($sql_goal);
$stmt_goal->bindValue(':goalnew', $goal, PDO::PARAM_STR);
$stmt_goal->bindValue(':goalupdate', $goal, PDO::PARAM_STR);
}
$stmt_goal->execute();
}
This works fine for updating existing goals as the key that is passed is the id that is in the goal table. However, the problem I run into is when they have new goals, the $goals array that gets passed from the form always starts at 0 and therefore the insert query tries to use 0, 1, 2, etc as the insert id. I'd rather have it automatically choose the next available id in the goals table.
I have tried to auto-populate what I think could be the new goal id's, but this is a bad idea as multiple people may hit the site as once and it could overlap. Any help is appreciated!

Answer 1

I’m going to make a few assumptions for this process to work for you.
The form in the case of a new entry is blank .
In the case of an update the form is populated from the database as
it stands.
On update the form is redisplayed from the database with a note at
the top that says the update has happened.
This is not bank data or hyper critical fault intolerant data. Which
for your application I don’t think it is. It is a form for
processing administrative data.
The Post process I suggest is a follows.
I suggest split up your insert process a little.
Insert/update into the master table. If it is an insert, grab the record Id from the crated row for use as your external key for the goals table.
Delete all entries from your goals table related to the external key. This will run even if there is no entry yet and will clear all goals should there be any. Literally rip out all rows and do a fresh insert.
Loop through the goals part of the post array using the master table’s record id as the external key for insertion. It is damn hard to keep track of the original goal record IDs for update. Because you cleared the table you don't worry with it as that data is in the post also. If the person edits the wording of a goal you don’t need to detect that to see if the goal needs updating as they are all reentered at once.
Display the form again with data pulled from the database. If there is an error and you output the result back into the form the user can always update again if there is a fault in the update process after the data is cleared from the goals table. The user will see the problem and try again if data is lost.
Again not how I handle bank data but for the form with an infinite number of goals that can be tacked on this is the easiest solution I have found.
Best of luck

Answer 2

So, after having the discussion over in G+, I ended up splitting things out:
1) Rename the arrays that are passed to goalsNew and goalsExisting
2) Changing the function to parse each array separately so it will perform an insert on new entries, but an update on existing entries. Below is the completed code, in case anyone cares. :)
<div id="goals">
<?php
$goals = getGoalsById($_GET['id']);
if (empty($goals)) echo "<p>Goal 1: <input type='text' size='40' name='goalsNew[]' /></p>";
else {
$i = 1;
foreach($goals as $goal) {
echo "<p>Goal {$i}: <input type='text' size='40' name=\"goalsExisting[{$goal['id']}]\" value=\"{$goal['goal']}\" /></p>";
$i++;
}
}
?>
</div>
And here is the function that does it all (and I renamed it dealingWithChildren from dealingWithGoals because this is going to be used for multiple child tables, but also because a new father should have a function called dealingWithChildren!
function dealWithChildren($childType, $childNew, $childExisting, $grant_id) {
$fieldName = substr($childType, 0, -1);
dbConnect();
global $DBH;
try {
// If there are no children at all, delete them all
if(empty($childNew) && empty($childExisting)) {
$sql_child_delete = "DELETE FROM $childType WHERE grant_id = $grant_id";
$stmt_child = $DBH->prepare($sql_child_delete);
$stmt_child->execute();
}
// If the user removed a child, delete those children
if(!empty($childExisting)) {
$sql_child_delete = "DELETE FROM $childType WHERE grant_id = $grant_id AND id NOT IN (";
$i = 0;
$len = sizeof($childExisting);
foreach($childExisting as $key=>$child) {
$sql_child_delete .= $key;
if ($len > 1 && $i < $len-1) $sql_child_delete .= ",";
$i++;
}
$sql_child_delete .= ")";
$stmt_del_child = $DBH->prepare($sql_child_delete);
$stmt_del_child->execute();
}
// If a user added any children
if(!empty($childNew)) {
foreach($childNew as $key=>$child) {
$sql_child_add[] = "INSERT INTO $childType ($fieldName, grant_id) VALUES (:childnew,$grant_id)";
foreach ($sql_child_add AS $sql_child) {
$stmt_child = $DBH->prepare($sql_child);
$stmt_child->bindValue(':childnew', $child, PDO::PARAM_STR);
}
$stmt_child->execute();
}
}
// If a user updated any children
if(!empty($childExisting)) {
foreach($childExisting as $key=>$child) {
$sql_child_update[] = "UPDATE $childType SET $fieldName = :childupdate WHERE id = $key";
foreach ($sql_child_update AS $sql_child) {
$stmt_child = $DBH->prepare($sql_child);
$stmt_child->bindValue(':childupdate', $child, PDO::PARAM_STR);
}
$stmt_child->execute();
}
}
} catch (PDOException $f) {
echo 'Database query failure: ' . $f->getMessage();
//exit;
}
dbDisconnect();
}