Nested JSON from 3 one-to-many Tables - php

Question

I'm building a Sencha-Touch 2 app and I have some trouble with the recuperation of my data from server side (mysql DB).
Here's my data model :
Table1 :
ID:int
description:varchar(100)
Table2 :
ID:int
description:varchar(100)
table1_ID:int
Table3 :
ID:int
name:varchar(100)
info:varchar(100)
table2_ID:int
Table1 is join to Table2 with a one-to-many relationship and same between Table2 and Table3.
What I want from server is a nested JSON who looks like this :
[
Table1_object1_ID: 'id' : {
Table1_object1_description: 'description',
Table2_Objects : [
'Table2_object1': {
Table2_object1_id : 'id',
Table2_object1_description : 'description'
Table3_Objects : [
table3_object1: {
Table3_object1_name : 'name',
Table3_object1_info : 'info',
},
table3_object2: {
Table3_object2_name : 'name',
Table3_object2_info : 'info',
},
table3_object3: {
Table3_object3_name : 'name',
Table3_object3_info : 'info',
},
etc...
],
},
'Table2_object2': {
Table2_object2_id : 'id',
Table2_object2_description : 'description'
Table3_Objects : [
...
]
},
etc....
]
},
Table1_object2_ID: 'id' : {
etc....
]
In my App, I use 3 Models for each Table, and ideally I want to save my data in 3 Stores, but that will be an other problem ;-)
The first Store (based on the Model from Table1) do a JsonP request to get the Nested JSON.
Actually my SQL request in the PHP file is simple :
SELECT *
FROM Table1
INNER JOIN Table2 ON Table1.ID = Table2.table1_ID
INNER JOIN Table3 ON Table2.ID = Table3.table2_ID;
I tried to make an array in PHP from my SQL results but cannot get the expect result.
I also try to change my SQL with GROUP BY and GROUP_CONCAT but same here, cannot get the JSON I want.
Some help would be really appreciate.

Answer 1

Runnable code with some sample data: http://codepad.org/2Xsbdu23
I used 3 distinct SELECTs to avoid the unnecessary repetitions.
Of course you have to customize the $result array to your exact desired JSON format, but I think it is not that hard.
// assume $t1/2/3 will be arrays of objects
$t1 =
SELECT Table1.*
FROM Table1
WHERE Table1.ID = 111
$t2 =
SELECT Table2.*
FROM Table2
WHERE Table2.table1_ID = 111
$t3 =
SELECT Table3.*
FROM Table2
INNER JOIN Table3 ON Table2.ID = Table3.table2_ID
WHERE Table2.table1_ID = 111
function array_group_by( $array, $id ){
$groups = array();
foreach( $array as $row ) $groups[ $row -> $id ][] = $row;
return $groups;
}
// group rows from table2/table3 by their parent IDs
$p2 = array_group_by( $t2, 'table1_ID' );
$p3 = array_group_by( $t3, 'table2_ID' );
// let's combine results:
$result = array();
foreach( $t1 as $row1 ){
$row1 -> Table2_Objects = isset( $p2[ $row1 -> ID ]) ? $p2[ $row1 -> ID ] : array();
foreach( $row1 -> Table2_Objects as $row2 )
$row2 -> Table3_Objects = isset( $p3[ $row2 -> ID ]) ? $p3[ $row2 -> ID ] : array();
$result[] = $row1;
}
echo json_encode( $result );