JSON from PHP – nested arrays - php

Question

I'm outputting some JSON from PHP, but I'm having difficulty understanding how to do nested arrays (at least I think that is what it is called)
I can output single sets, for example, "type": "Feature" but how would I do
"geometry": {
"type": "Point",
"coordinates": [-77.03238901390978,38.913188059745586]
},
For example, the desired output for one item in the JSON array might be:
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [-77.03238901390978,38.913188059745586]
},
"properties": {
"title": "Mapbox DC",
"description": "1714 14th St NW, Washington DC",
"marker-color": "#fc4353",
"marker-size": "large",
"marker-symbol": "monument"
}
},
And my code so far looks like this:
<?php
$projects = $pages->find('template=project-detail, sort=sort');
$projects_array = array();
foreach ($projects as $project) {
$title = $project->title;
$long = $project->project_location_marker_long;
$lat = $project->project_location_marker_lat;
$projects_array[] = array(
'title' => $title
);
}
$projects_json = json_encode($projects_array, true);
?>
<script>
var geojson = <?php echo echo $projects_json; ?>
</script>
Which generates something like the following:
[{
"title": "Steel Strike 1980"
}, {
"title": "Chapel Flat Dyke Boat"
}]

Answer 1

A nested array is simple to create. Here is one example:
$my_array = array(
'string_example' => 'asdf',
'integer_example' => 42,
'array_example' => array() // this array is nested
);
Inside this nested array, you could put anything you'd like. For instance, let's put the exact same thing in it:
$my_array = array(
'string_example' => 'asdf',
'integer_example' => 42,
'array_example' => array(
'string_example' => 'asdf',
'integer_example' => 42,
'array_example' => array()
)
);
So working from your code example, here is a start, given the data you included:
foreach ($projects as $project) {
$title = $project->title;
$long = $project->project_location_marker_long;
$lat = $project->project_location_marker_lat;
$projects_array[] = array(
'geometry' => array(
'coordinates' => array($long, $lat)
)
'properties' => array(
'title' => $title
)
);
}
This will result in the following json when encoded:
{
"geometry": {
"coordinates": [-77.03238901390978,38.913188059745586]
},
"properties": {
"title": "Mapbox DC",
}
}

Answer 2

There's a simple way to figure this out. Just take your example JSON, decode it and see what the output looks like:
<?php
$json = '
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [-77.03238901390978,38.913188059745586]
},
"properties": {
"title": "Mapbox DC",
"description": "1714 14th St NW, Washington DC",
"marker-color": "#fc4353",
"marker-size": "large",
"marker-symbol": "monument"
}
}';
var_export(json_decode($json, true));
Output:
array (
'type' => 'Feature',
'geometry' =>
array (
'type' => 'Point',
'coordinates' =>
array (
0 => -77.032389013909778,
1 => 38.913188059745586,
),
),
'properties' =>
array (
'title' => 'Mapbox DC',
'description' => '1714 14th St NW, Washington DC',
'marker-color' => '#fc4353',
'marker-size' => 'large',
'marker-symbol' => 'monument',
),
)

Answer 3

if you like to encode for example the lat/lon of your sample code it would be:
$title = $project->title;
$long = $project->project_location_marker_long;
$lat = $project->project_location_marker_lat;
$projects_array[] = array(
'title' => $title,
'coordinates' => array($lat,$lon)
);
this will result in something like this:
[{
"title": "Steel Strike 1980",
"coordinates": [-77.03238901390978,38.913188059745586]
}, {
"title": "Chapel Flat Dyke Boat",
"coordinates": [-77.03238901390978,38.913188059745586]
}]