Get DataTables to output an array of objects in appropriate columns - json

Question

I'm working on a chemicals database web application. Using DataTables 1.10.16 and CakePHP 3.5
Cake is producing a JSON feed. A sample is below:
[
{
"id": 1,
"app_id": "ID000001",
"name": "Chromium",
"ecs": [
{
"id": 1,
"value": "123-456-7"
},
{
"id": 32,
"value": "222-333-444"
},
],
"cas": [
{
"id": 1,
"value": "987-654-3"
}
]
},
]
For certain chemicals there are multiple EC (ecs in the JSON) and CAS Numbers (cas in the JSON).
I don't know if/how it's possible to get DataTables to loop through these objects, outputting them in the appropriate columns, with a separator such as a <br> tag.
My table markup looks like this:
<table id="substancesTable" class="table responsive display table-striped" cellspacing="0" width="100%">
<thead>
<tr>
<th>Application ID</th>
<th>EC Number</th>
<th>CAS Number</th>
<th>Chemical Name</th>
</tr>
</thead>
</table>
And in my Javascript I'm doing this:
$('#substancesTable').DataTable({
"processing": true,
"serverSide": true,
"searching": false,
"ajax": {
"url" : "/get-substances.json",
"method" : "POST",
"dataSrc":""
},
"columns": [
{ "data": "app_id", "name" : "app_id" },
{ "data": "ecs", "name" : "ec_number" },
{ "data": "cas", "name" : "cas_number" },
{ "data": "name", "name" : "name" },
]
});
This works in terms of populating the "Application ID" and "Chemical Name" columns - but that's because there is a simple 1:1 mapping in the JSON (no arrays/objects).
The output for the "EC Number" and "CAS Number" columns is just [object Object] and is repeated the number of objects there are. In the example above there are 2 EC Numbers for this chemical so the output under "EC Number" is [object Object],[object Object]
Can anyone assist with this? I'd like the output to be generated by looping through my JSON and introducing a break between each item, e.g.
123-456-7<br>222-333-444

Answer 1

You'll be needing a render function like this:
{
"data": "ecs",
"name": "ec_number",
"title":"EC Number",
"render": function(d,t,r){
return d.map(function(e) {
return e.value;
}).join("<br/>");
}
}
Working JSFiddle here.