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Merge pull request #18 from npu3pak/feature/sound_null_safety
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Feature/sound null safety
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@npu3pak
npu3pak authored Mar 28, 2022
2 parents 1313212 + e63f138 commit dee6320
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222 changes: 80 additions & 142 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,7 @@ import 'package:dart_json/dart_json.dart';

### String parsing
```dart
final str = """
{"title": "Roadside Picnic", "year": 1972, "inStock": false }
""";
final str = '{"title": "Roadside Picnic", "year": 1972, "inStock": false}';
final json = Json.parse(str);
```

Expand Down Expand Up @@ -59,57 +56,17 @@ Json json = Json.object();
json["int"].intValue = 1;
json["string"].stringValue = "str";
json["double"].doubleValue = 1.1;
json["double"].numValue = 1.1;
json["bool"].boolValue = true;
```

The same using dynamic types:
```dart
Json json = Json.object();
json["int"].dynamicValue = 1;
json["string"].dynamicValue = "str";
json["double"].dynamicValue = 1.1;
json["bool"].dynamicValue = true;
```

### Reading values
```dart
final intVal = json["year"].intValue;
final stringVal = json["title"].stringValue;
final doubleVal = json["price"].doubleValue;
final boolVal = json["inStock"].boolValue;
```

With dynamic types:
```dart
final intVal = json["year"].dynamicValue;
final stringVal = json["title"].dynamicValue;
final doubleVal = json["price"].dynamicValue;
final boolVal = json["inStock"].dynamicValue;
```

### Checking if a value exists
You can check if the JSON contains the element with the giving name:
```dart
if (item["element"].dynamicValue != null) {
}
```
Example:

```dart
final json = Json([
{"name": "John"},
{
"name": "Nick",
"extra": {"phone": "123-4567"}
}
]);
for (var item in json.list) {
if (item["extra"].dynamicValue != null) {
print(item["name"].stringValue);
}
}
int? intVal = json["year"].intValue;
String? stringVal = json["title"].stringValue;
double? doubleVal = json["price"].doubleValue;
num? numValue = json["price"].numValue;
bool? boolVal = json["inStock"].boolValue;
```

### Making JSON objects
Expand All @@ -136,28 +93,51 @@ json["contacts"]["phones"] = Json.list();
json["contacts"]["phones"].list.add(Json("754-3010"));
```

### Accessing values from a nested object
### Accessing values of a nested object
```dart
final value1 = j["inner1"]["key1"].stringValue;
final value2 = j["inner1"]["inner2"]["key2"].stringValue;
final value = j["root"]["nested"].stringValue;
```

### Working with a JSON list
You can create a JSON list from a list of JSON objects:
In the example above the keys "root" and "nested" **must not be null**, otherwise the JsonException will be thrown.
If you need to parse the nested JSON with keys that can be null, you should check it explicitly.

```dart
final value1 = j["inexisted"]["nested"].stringValue; // JsonException
final value2 = j["inexisted"].isExist
? j["inexisted"]["nested"].stringValue
: null; // null
```

You can also use the shortcut.
```dart
final value = j["inexisted"].optional["nested"].stringValue; // null
```

In the example, we marked the path "inexisted" as **optional**. The JSON parser will know that the "inexisted" can be null. And the "nested" and all the keys to the right side of "inexisted" can be null as well.

### Null checks
You can check if the JSON value is **not null**:
```dart
final json = Json.empty(); // json with null
print(json != null) // true
print(json.isExist) // false
```

You can check if the JSON object contains the element with the giving name:
```dart
final item1 = Json({"name": "John"});
final item2 = Json({"name": "Nick"});
final json = Json([item1, item2]);
final json = Json.object(); // json with {}
print(json.isExist) // true
print(json["key"].isExist) // false
```

You can create a JSON list from a list of dictionaries:
### Working with a JSON list
You can create a JSON list:

```dart
final json = Json([
{"name": "John"},
{"name": "Nick"},
]);
final fromAListOfValues = Json(["John", "Jack"]);
final fromAListOfDictionaries = Json([{"name": "John"}, {"name": "Nick"}]);
final fromAListOfJsons = Json([Json("John"), Json("Jack")]);
```

You can access a list of a JSON object with the **list** property.
Expand All @@ -169,34 +149,24 @@ List<Json> jsonList = json.list;
You can create an empty array and fill it with items using the **add()** method:

```dart
final item1 = Json({"item": 1});
final item2 = Json({"item": 2});
final json = Json.list(); // []
json.list.add(item1); // [{"item":1}]
json.list.add(item2); // [{"item":2}]
json.list.add(Json({"item": 1})); // [{"item":1}]
json.list.add(Json({"item": 2})); // [{"item":1}, {"item":2}]
```

You can modify a list of items like this:

```dart
final item1 = Json({"item": 1});
final item2 = Json({"item": 2});
final json = Json([item1]); // [{"item":1}]
json.list.remove(item1); // []
json.list.add(item2); // [{"item":2}]
```

### Parsing a response string
### Working with an objects list
```dart
final responseString = """
{
"books": [
{"title": "Hard to Be a God", "year": 1964, "inStock": true, "price": 5.99 },
{"title": "Prisoners of Power", "year": 1971, "inStock": true, "price": 5.99 },
{"title": "Roadside Picnic", "year": 1972, "inStock": false }
]
}
""";
class Book {
final String title;
Expand All @@ -207,81 +177,43 @@ class Book {
Book({this.title, this.year, this.inStock, this.price});
}
main() {
Json json = Json.parse(responseString);
List<Book> books = json["books"].list.map(
(j) => Book(
title: j["title"].stringValue,
year: j["year"].intValue,
inStock: j["inStock"].boolValue,
price: j["price"].doubleValue,
),
).toList();
}
// You can also use the convenience **toObjectList()** method
books = json["books"].toObjectList(
(j) => Book(
title: j["title"].stringValue,
year: j["year"].intValue,
inStock: j["inStock"].boolValue,
price: j["price"].doubleValue,
),
);
```
### Making JSON from an objects list
```dart
final books = [
Book(title: "Beetle in the Anthill", year: 1979, inStock: true, price: 5.99)
];
Json listJson = Json.list();
for (final book in books) {
var itemJson = Json.object();
itemJson["title"].stringValue = book.title;
itemJson["year"].intValue = book.year;
itemJson["inStock"].boolValue = book.inStock;
itemJson["price"].doubleValue = book.price;
listJson.list.add(itemJson);
}
print(listJson.asPrettyString());
// You can use the convenience **Json.fromObjectList** method as well
listJson = Json.fromObjectList(books, (item) {
// Making the JSON from the object list
Json listJson = Json.fromObjectList(books, (Book item) {
var j = Json.object();
j["title"].stringValue = item.title;
j["year"].intValue = item.year;
j["inStock"].boolValue = item.inStock;
j["price"].doubleValue = item.price;
return j;
});
```
### Parsing custom types
You must implement a JsonAdapter to parse values of a custom type.
// Making the object list from the JSON
List<Book>? objectList = listJson.toObjectList(
(j) => Book(
title: j["title"].stringValue!,
year: j["year"].intValue!,
inStock: j["inStock"].boolValue!,
price: j["price"].doubleValue!,
),
);
```

### Working with custom types
Sometimes you need to work with enums, dates, and other custom types in JSON.
```dart
final jsonStr = """
{
"name": "John",
"status": "active"
}
""";
class User {
final String name;
final Status status;
User({this.name, this.status});
}
enum Status { active, old }
```

You can implement a JsonAdapter to parse values of a custom type.

```dart
class StatusAdapter implements JsonAdapter<Status> {
@override
Status fromJson(Json json) {
Status? fromJson(Json json) {
switch (json.stringValue) {
case "active":
return Status.active;
Expand All @@ -293,7 +225,10 @@ class StatusAdapter implements JsonAdapter<Status> {
}
@override
Json toJson(Status value) {
Json toJson(Status? value) {
if (value == null) {
return Json.empty();
}
switch (value) {
case Status.active:
return Json("active");
Expand All @@ -304,14 +239,17 @@ class StatusAdapter implements JsonAdapter<Status> {
}
}
}
```

main() {
final json = Json.parse(jsonStr);
final user = User(
name: json["name"].stringValue,
status: json["status"].get(StatusAdapter())
);
}
Now you can work with JSON values of the custom type using the **get** and **set** methods.
```dart
final valueJson = Json.empty();
valueJson.set(Status.active, StatusAdapter());
Status? valueStatus = valueJson.get(StatusAdapter());
final objectJson = Json.object();
objectJson["key"].set(Status.active, StatusAdapter());
Status? ojectStatus = objectJson["key"].get(StatusAdapter());
```

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