Database error 1452 - php

Question

I'm working on this project that have foreign keys on two tables. By using a form I'm trying to insert a new record to the database. And there's also an image path in the db and I'm inserting the image path via the form. I'm using codeigniter file upload library. Other fields of the database table get updated when i submit the form even the foreign key field. But the image path is not updating. When I submit the form it shows this error.
A Database Error Occurred
Error Number: 1452
Cannot add or update a child row: a foreign key constraint fails (`bfh`.`products`, CONSTRAINT `category_fk` FOREIGN KEY (`category_id`) REFERENCES `categories` (`id`))
INSERT INTO `products` (`img`) VALUES ('assets/img//sakya.PNG')
Filename: C:/xampp/htdocs/CI-skeleton/system/database/DB_driver.php
Line Number: 691
Controller
public function add_product()
{
$result = 0;
$cat_id = $this->input->post("category_id");
$type_id = $this->input->post("type_id");
$pname = $this->input->post("p_name");
$images = $this->input->post("images");
$images = $_FILES['images']['name'];
$price = $this->input->post("price");
$this->load->model("Products_Model");
$product_id = $this->Products_Model->add_product( $cat_id, $type_id, $pname, $price);
if ($product_id != 0) {
$result = $this->Products_Model->add_product_images($images);
}
if ($result && $_FILES['images']['name'][0] != "") {
$this->load->model('Image_Upload');
$result = $this->Image_Upload->upload("assets/img");
}
$this->session->set_flashdata('result', $result);
redirect('Products');
}
Model
public function add_product( $cat_id, $type_id, $pname, $price)
{
$result = $this->db->get_where("products", array('name' => $pname));
if ($result->num_rows() != 0) {
return 0; // record already exists
} else {
$data = array(
'category_id' => $cat_id,
'type_id' => $type_id,
'name' => $pname,
'price' => $price
);
if( !$this->db->insert('products', $data)) {
return -1; // error
}else{
return $this->db->insert_id();
}
return 1; // success
}
}
public function add_product_images($images)
{
$path = "assets/img/";
foreach ($images as $image) {
// if no images were given for the item
if ($image == "") {
return 1;
}
$data = array(
'img' => $path."/".$image
);
if ( ! $this->db->insert('products', $data)) {
return 0; // if something goes wrong
}
}
return 1;
}

Answer 1

You should use "update" query on the behalf of insert in add_product_images().
Because "insert" will add a new record of the product and there is no any category id(Foreign Key) with this that's why shows this error.
So try to update image.

Answer 2

you have two variables with the same name and thats the problem.
You need have different variable name.
I hope this will help you.

Answer 3

there are some problems in this script
if model you wrote, function add product. if your query failed, returns -1 otherwise return product Id
but if product was in database it returns 0, then in controller: you check if product_id != 0 then insert images. so you don't care if product didn't exists in database, you failed you insert that in table or not
in add_product_images you check if ($image == "") . I don't understand how you get that image array ($images) is empty if this statement is true. you can check if (sizeof($images) == 0) before foreach to check emptiness of image array ($images)