deep_pick 0.5.0

A library to access deep nested values inside of dart data structures, like returned from `dynamic jsonDecode(String source)`.

0.5.0

• New context API. You can now attach relevant additional information for parsing directly to the Pick object. This allows passing information into fromPick constructors without adding new parameters to all constructors in between.

// Add context
final shoes = pick(json, 'shoes')
    .addContext('apiVersion', "2.3.0")
    .addContext('lang', "en-US")
    .asListOrEmpty((p) => Shoe.fromPick(p.required()));

import 'package:version/version.dart';

// Read context
factory Shoe.fromPick(RequiredPick pick) {
  // read context API
  final version = pick.fromContext('newApi').required().let((pick) => Version(pick.asString()));
  return Shoe(
    id: pick('id').required().asString(),
    name: pick('name').required().asString(),
    // manufacturer is a required field in the new API
    manufacturer: version >= Version(2, 3, 0)
        ? pick('manufacturer').required().asString()
        : pick('manufacturer').asStringOrNull(),
    tags: pick('tags').asListOrEmpty(),
  );
}

• Breaking: Pick and RequiredPick have chained their constructor signature. path is now a named argument and context has been added.

- RequiredPick(this.value, [this.path = const []])
+ RequiredPick(this.value, {this.path = const [], Map<String, dynamic> context})

• The path is now correctly forwarded after Pick#call or Pick#asListOrEmpty and always shows the full path since origin

0.4.3

• Fix error reporting for asMapOr[Empty|Null] and don't swallow parsing errors
• Throw Map cast errors when parsing, not lazily when accessing the data

0.4.2

• Fix error reporting of asListOrNull(mapToUser) and asListOrEmpty(mapToUser). Both now return errors during mapping and don't swallow them

0.4.1

• Print correct path in error message when json is null
• asDateTime() now skips parsing when the value is already a DateTime

0.4.0

Map objects

New APIs to map picks to objects and to map list elements to objects.

RequiredPick.let<R>(R Function(RequiredPick pick) block): R
Pick.letOrNull<R>(R Function(RequiredPick pick) block): R

RequiredPick.asList<T>([T Function(Pick) map]): List<T> 
Pick.asListOrNull<T>([T Function(Pick) map]): List<T> 
Pick.asListOrEmpty<T>([T Function(Pick) map]): List<T> 

Here are two example how to actually use them.

// easily pick and map objects to dart objects
final Shoe oneShoe = pick(json, 'shoes', 0).letOrNull((p) => Shoe.fromPick(p));

// map list of picks to dart objects
final List<Shoe> shoes = 
     pick(json, 'shoes').asListOrEmpty((p) => Shoe.fromPick(p.required()));

Required picks

Pick now offers a new required() method returning a RequiredPick. It makes sure the picked value exists or crashes if it is null. Because it can't be null, RequiredPick doesn't offer fallback methods like .asIntOrNull() but only .asInt(). This makes the API a bit easier to use for values you can't live without.

// use required() to crash if a object doesn't exist
final name = pick(json, 'shoes', 0, 'name').required().asString();
print(name); // Nike Zoom Fly 3

Note: Calling .asString() directly on Pick has been deprecated. You now have to call required() first to convert the Pick to a RequiredPick or use a mapping method with fallbacks.

Pick deeper

Ever got a Pick/RequiredPick and you wanted to pick even further. This is now possible with the call method. Very useful in constructors when parsing methods.

  factory Shoe.fromPick(RequiredPick pick) {
    return Shoe(
      id: pick('id').required().asString(),
      name: pick('name').required().asString(),
      manufacturer: pick('manufacturer').asStringOrNull(),
      tags: pick('tags').asListOrEmpty(),
    );
  }

Bugfixes

• Don't crash when selecting a out of range index from a List
• .asMap(), .asMapOrNull() and .asMapOrEmpty() now consistently return Map<dynamic, dynamic> (was Map<String, dynamic>)

---

Also the lib has been converted to use static extension methods which were introduced in Dart 2.6

0.3.0

asMap now expects the key type, defaults to dynamic instead of String

-Pick.asMap(): Map<String, dynamic>
+Pick.asMap<T>(): Map<T, dynamic>

0.2.0

New API! The old parse* methods are now deprecated, but still work. Replace them with the new pick(json, arg0-9...) method.

- final name = parseJsonToString(json, 'shoes', 0, 'name');
+ final name = pick(json, 'shoes', 0, 'name').asString();

pick returns a Pick which offers a rich API to parse values.

.asString()
.asStringOrNull()
.asMap()
.asMapOrEmpty()
.asMapOrNull()
.asList()
.asListOrEmpty()
.asListOrNull()
.asBool()
.asBoolOrNull()
.asBoolOrTrue()
.asBoolOrFalse()
.asInt()
.asIntOrNull()
.asDouble()
.asDoubleOrNull()
.asDateTime()
.asDateTimeOrNull()

0.1.1

• pubspec description updated

0.1.0

• Initial version