PHP assigning only specific values into an incremental variable during a loop

Question

I have this array:

Array
(
    [users] => Array
        (
            [0] => Array
                (
                    [column] => email
                    [value] => [email protected]
                )

            [1] => Array
                (
                    [column] => nickname
                    [value] => dpucci
                )

        )

    [social] => Array
        (
            [0] => Array
                (
                    [column] => user_id
                    [value] => opweirpor
                )

        )

)

Starting from this array I'll have to build a string that will look like this:

insert(users, array(email=>[email protected],nickname=>dpucci)

And another like this:

insert(social, array(user_id=>opweirpor)

This is what I am doing:

foreach ($tables as $table => $queries) {
    foreach ($queries as $query) {
        $insert .= $query['column'] . '=>' . $query['value'] . ',';
    }
    echo 'insert(' . $table . ', array(' . $insert . ')';
}

The problem is that the result I am getting is the following:

insert(users, array(email=>[email protected],nickname=>dpucci)

and:

insert(social, array(email=>[email protected], nickname=>dpucci, user_id=>opweirpor)

This is because the variable $insert is incremented each new loop and it is adding ALL the results instead that only the ones I need for each $tables loop.

How can I achieve the expected result?

luiges90 · Accepted Answer · 2013-07-11 14:01:11Z

Because you keep appending your string to the same $insert in the inner loop, which is ran many times. Just clear the insert variable after you have finished with it, i.e. after your inner loop. (Untested)

foreach ($tables as $table => $queries) {
    foreach ($queries as $query) {
        $insert .= $query['column'] . '=>' . $query['value'] . ',';
    }
    echo 'insert(' . $table . ', array(' . $insert . ')';

    // add this line
    $insert = "";

}

or, put it before the inner foreach loop, which has an advantage to ensure $insert is not polluted with previous codes or otherwise uninitialized giving PHP warnings.

foreach ($tables as $table => $queries) {

    // add this line
    $insert = "";

    foreach ($queries as $query) {
        $insert .= $query['column'] . '=>' . $query['value'] . ',';
    }

    echo 'insert(' . $table . ', array(' . $insert . ')';

}

However, your code actually creates

insert(users, array(email=>[email protected],nickname=>dpucci,)

Note the comma after dupcci. Which I don't think is what you want. To fix this, simply remove the trailing comma with substr:

foreach ($tables as $table => $queries) {

    // add this line
    $insert = "";

    foreach ($queries as $query) {
        $insert .= $query['column'] . '=>' . $query['value'] . ',';
    }

    // add one more line here
    $insert = substr($insert, 0, -1);

    echo 'insert(' . $table . ', array(' . $insert . ')';

}

Also, check your desired output. It seems that the brackets are not balanced and the strings are unquoted. Are you sure it is what you want?

web-nomad · Accepted Answer · 2013-07-11 13:53:40Z

2

Reset the variable $insert.

foreach ($tables as $table => $queries) {
    $insert = '';
    foreach ($queries as $query) {
        $insert .= $query['column'] . '=>' . $query['value'] . ',';
    }
    echo 'insert(' . $table . ', array(' . $insert . ')';
}

answered Jul 11, 2013 at 13:53

web-nomad

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