How to generate JSON in realtime/dynamically from a MySQL database - php

Question

So I want to export a JSON file from a MySQL database table, a php script that runs weekly and exports JSON file from a specific table.
This is sort of the thing I want to achieve:
<?php
$json_file_name = "File_export.json";
$json_file_name = str_replace(" ", "_", $json_file_name);
$con = mysqli_connect("", "", "", "");
if (mysqli_connect_errno($con)) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$date_range = array(
"start" => date("Y-m-d H:i:s", strtotime("-7 days")),
"end" => date("Y-m-d H:i:s", strtotime("now")),
);
and so on
if(!empty($json_data) && count($json_data) > 1)
{
$json_file_data = "";
$fp = fopen($json_file_name, 'w');
foreach($json_data as $row)
{
$json_file_data .= implode(",", $row) . "\n";
}
fwrite($fp, $json_file_data);
fclose($fp);
What is the best way to achieve the same.
Thank you :)

Answer 1

If your database table not too large, you can fetch all rows into a single array, then turn that array into JSON automatically without looping. This will generate JSON with column values as a list:
// $con is connection, $json_filename is name of filename to write
$query = "select * from MyTable";
// Fetch all rows into $json_data array
$result = mysqli_query($con, $query);
$json_data = mysqli_fetch_all($result);
mysqli_close($con);
// Turn data into JSON and write to file
$json = json_encode($json_data);
file_put_contents($json_filename, $json);
Example output:
[["name1","address1"],["name2","address2"]]
If your database table is a little bigger, it is better to write each line as it is generated. The code below will create a JSON object for each row.
$query = "select * from MyTable";
$result = mysqli_query($con, $query);
// Open output file
$fp = fopen($json_file_name, 'w');
// Write JSON list start
fwrite($fp, '[');
// Write each object as a row
$isFirstRow = true;
while ($row = mysqli_fetch_assoc($result)) {
if (!$isFirstRow) {
fwrite($fp, ',');
} else {
$isFirstRow = false;
}
fwrite($fp, json_encode($row));
}
// Write JSON list end
fwrite($fp, ']');
// Close file and MySQL connection
fclose($fp);
mysqli_close($con);
Example output:
[{"name": "name1", "address": "address1"},{"name": "name2", "address": "address2"}]

Answer 2

I think you also want to change this line:
$json_file_data .= implode(",", $row) . "\n";
to this:
$json_file_data[] = implode(",", $row);
Which will cause this:
$json = json_encode($json_data);
To deliver a json array of your database rows.