Problem with insert value in database with json_encode

I want insert on a row of database table, following value with following php code(foreach) but after insert get following error, what do i do?

Values:

<div class="column">
    <input type="text" name="start_date[1][]" value="1111">
    <input type="text" name="end_date[1][]" value="1111">
    <input type="text" name="price_change[1][]" value="1111">
</div>
<div class="column">
    <input type="text" name="start_date[2][]" value="2222">
    <input type="text" name="end_date[2][]" value="2222">
    <input type="text" name="price_change[2][]" value="2222">
</div>
<div class="column">
    <input type="text" name="start_date[3][]" value="3333">
    <input type="text" name="end_date[3][]" value="3333">
    <input type="text" name="price_change[3][]" value="3333">
</div>

Php code:

    $residence_ups_input = $this->input->post('start_date');
    $residence_upe_input = $this->input->post('end_date');
    $residence_upc_input = $this->input->post('price_change');
    var_dump($residence_ups_input); // output this is: nobool(false)
    $residence_p = array();
  开发者_如何学运维  foreach ($residence_ups_input as $idx => $name) { //line 134        
        $residence_p[] = array(
            'start_date' => $residence_ups_input[$idx],
            'end_date' => $residence_upe_input[$idx],
            'price_change' => $residence_upc_input[$idx]
        );
    }
    ;
    $data = array(
        //'name' => $this -> input -> post('name'),
        'residence_p' => json_encode($residence_p)
    );
    $this->db->insert('tour_foreign', $data);

Error:

A PHP Error was encountered

Severity: Warning

Message: Invalid argument supplied for foreach()

Filename: inser.php

Line Number: 134

Change all columns:

<div class="column">
    <input type="text" name="start_date[1][]" value="1111">
    <input type="text" name="end_date[1][]" value="1111">
    <input type="text" name="price_change[1][]" value="1111">
</div>
....

to:

<form method="post">
<div class="column">
    <input type="text" name="start_date[]" value="1111">
    <input type="text" name="end_date[]" value="1111">
    <input type="text" name="price_change[]" value="1111">
</div>
....

</form>

replace

 foreach ($residence_ups_input as $idx => $name) { 

with

 foreach (get_object_vars($residence_ups_input) as $idx => $name) { 

you are passing an object to foreach, it wants an associative array. From now on do

json_decode($string, true)

instead of

json_decode($string)

and access the variable like this:

$var['key'];

instead of $var->key

the $residence_ups_input variable is not an array

use this code :

array_push($residence_ups_input,$this->input->post('start_date'));
array_push($residence_upe_input,$this->input->post('end_date'));
array_push($residence_upc_input,$this->input->post('price_change'));

to get the values then use the foreach()