When dealing with large JSON data, we should offload the parsing code to a worker isolate and the easiest way to do this is with the compute() function.Īs of Flutter 2.8, the compute() function can return the result data to the main isolate in constant time, thanks to the fast concurrency features introduced by Dart 2.15. Here it is, running on Dartpad: JSON Parsing with isolates. It was derived from JavaScript, but many modern programming languages include code to generate and parse JSON-format data. This uses the Riverpod package to tie everything together, but any other dependency injection package would work too. If the json cannot be decoded or if the encoded data is deeper than the recursion limit then it returns NULL. Now that we've taken care of the JSON parsing and networking code, we can create a simple Flutter app that shows all the search results. 44 Set and get JSON value, 43 Json decode() function, 177 JSON formatting tools, 197 JSONP, 70 JSON.parse() function, 197 JSON.php, 198 Jumbotron, 90. Return values: This function returns the encoded JSON value in appropriate PHP type. This video about Async vs Isolates explains it very well. There is a fundamental difference between waiting without blocking (using async code) and running code in parallel (using isolates). In other words: we can safely perform IO using Future-based APIs, and Dart will do the right thing under the hood. To parse JSON strings use the native JSON.parse method instead. Now let us see simple example which uses jsondecode () of PHP in a HTML structure. Description: Takes a well-formed JSON string and returns the resulting JavaScript value. And when an IO operation is done, the result is passed back to the main isolate. This jsondecode () function of PHP takes JSON encoded string as input and returns the value that is decoded to PHP objects which of PHP data types and if the decoding is not possible then this function returns null instead of PHP objects. This code uses the http package to fetch the data from the network, and then delegates the parsing logic to the SearchResultsParser class we have created.īut shouldn't the http.get() call also run on the worker isolate?Īs it turns out, networking and file IO run on a separate task runner. Import 'dart:convert' import 'package:flutter/foundation.dart' class SearchResultsParser