json_contains 1.0.3

A library for checking if a JSON object contains another JSON object.

Table of Contents

• About
• List behavior
• My real usecase

🚀 About

JSON Contains is implemented in order to check if one JSON objects is contained in another. In the example below the comparison will be true.

final firstJson = {
    "name": "John",
    "age": 30,
    "address": {"street": "Main Street", "city": "New York"}
};

final secondJson = {
    "name": "John",
    "address": {"city": "New York"}
};

final result = jsonContains(json: firstJson, jsonToContain: secondJson);
print(result); // true

[...] List behavior

By default when two lists are compared:

• lenght of the lists is not compared
• ordering of items is not compared

For example, the following will be true:

  final firstJson = {
    "skills": ["Dart", "Flutter", "React", "Python"],
  };

  final secondJson = {
    "skills": ["Flutter", "Dart"]
  };

  final result = jsonContains(json: firstJson, jsonToContain: secondJson);
  print(result); // true

  final firstJson = {
    "name": "John",
    "skills": ["Dart", "Flutter", "React"],
    "projects": [
      {
        "title": "Project A",
        "tags": ["open-source", "popular"]
      },
      {
        "title": "Project B",
        "tags": ["internal"]
      }
    ]
  };

  final secondJson = {
    "skills": ["React", "Dart"],
    "projects": [
      {
        "tags": ["popular", "open-source"]
      }
    ]
  };
  final result = jsonContains(json: firstJson, jsonToContain: secondJson);
  print(result); // true

You can modify this behavior with JsonContainsListBehavior by setting compareOrder/compareLenght to true

final  json  = {
"skills": ["Dart", "Flutter", "React"],
};
final  jsonToContain  = {
"skills": ["Flutter", "Dart"]
};

final  listBehaviour  =  JsonContainsListBehavior(compareOrder:  true);

final  result  =  jsonContains(json:  json, jsonToContain:  jsonToContain, listBehavior:  listBehaviour);

print(result); // false

final  json  = {
"skills": ["Flutter", "Dart", "React"],
};

final  jsonToContain  = {
"skills": ["Flutter", "Dart"]
};

final  listBehaviour  =  JsonContainsListBehavior(compareLenght:  true);

final  result  =  jsonContains(json:  json, jsonToContain:  jsonToContain, listBehavior:  listBehaviour);

print(result); // false

My real usecase

I needed this in an IoT project, here was my use case:

• mobile app is connected to a socket
• IoT device is connected to a socket
• mobile app sends a "desired state change" update to the socket
• IoT device picks up that change
• IoT device sends the "change in its current state" to the socket all the time
• In order for the app to "know" the IoT device is has changed to the desired state it needs to check if the JSON object reported by the device contains its "desired state change" JSON object