Flutter - Create Map from two JSON - json

Question

I need to create a Map dictionary for this two JSON for creating a view like App Store/Play Store so, a view with cell grouped by different heading.
First JSON
[
{
"category_id":"1",
"language_code":"it",
"category_name":"punti d'interesse",
"category_description":"descrizione",
"is_hidden":"0"
},
{
"category_id":"2",
"language_code":"it",
"category_name":"farmacie",
"category_description":"desc farm",
"is_hidden":"0"
}
]
Second JSON
[
{
"poi_id":"1",
"category_id":"1",
"language_code":"it",
"poi_name":"chiese",
"poi_description":"",
"poi_image":"church.jpg"
},
{
"poi_id":"2",
"category_id":"1",
"language_code":"it",
"poi_name":"monumenti",
"poi_description":"",
"poi_image":"monument.jpg"
},
{
"poi_id":"3",
"category_id":"2",
"language_code":"it",
"poi_name":"musei",
"poi_description":"",
"poi_image":"museum.jpg"
}
]
How can I create?

Answer 1

Here you go:
import 'dart:convert';
void main() {
// Your first json
List<Map<String, String>> map1 = [
{
"category_id": "1",
"language_code": "it",
"category_name": "punti d'interesse",
"category_description": "descrizione",
"is_hidden": "0"
},
{
"category_id": "2",
"language_code": "it",
"category_name": "farmacie",
"category_description": "desc farm",
"is_hidden": "0"
}
];
// Your second json
List<Map<String, String>> map2 = [
{
"poi_id": "1",
"category_id": "1",
"language_code": "it",
"poi_name": "chiese",
"poi_description": "",
"poi_image": "church.jpg"
},
{
"poi_id": "2",
"category_id": "1",
"language_code": "it",
"poi_name": "monumenti",
"poi_description": "",
"poi_image": "monument.jpg"
},
{
"poi_id": "3",
"category_id": "2",
"language_code": "it",
"poi_name": "musei",
"poi_description": "",
"poi_image": "museum.jpg"
}
];
// The function that interests you (returns a map in the format you wanted)
Map<String, List> convertData(List<Map> categories, List<Map> pois) {
Map<String, List> result = {};
for (var category in categories) {
List<Map> poisOfCategory = [];
for (var poi in pois) {
if (category['category_id'] == poi['category_id']) {
poisOfCategory.add(poi);
}
}
result[category['category_name']] = poisOfCategory;
}
return result;
}
// Prints the map as a string
print(json.encode(convertData(map1, map2)));
}
The output would be:
{
"punti d'interesse":[
{
"poi_id":"1",
"category_id":"1",
"language_code":"it",
"poi_name":"chiese",
"poi_description":"",
"poi_image":"church.jpg"
},
{
"poi_id":"2",
"category_id":"1",
"language_code":"it",
"poi_name":"monumenti",
"poi_description":"",
"poi_image":"monument.jpg"
}
],
"farmacie":[
{
"poi_id":"3",
"category_id":"2",
"language_code":"it",
"poi_name":"musei",
"poi_description":"",
"poi_image":"museum.jpg"
}
]
}