General serialization for Dart objects. #
Save and restore objects flexibly.
This can serialize and de-serialize objects to multiple different formats. It is most useful if you have Dart on both ends, rather than needing to communicate with an external system. It can handle cycles, inheritance, getters and setters, private or final fields set via constructors, objects serialized in different ways at different times, and other complex options. It can handle serializing acyclic objects with only public fields to a simple JSON format, but might be more heavyweight than is necessary if that's the only requirement.
This has no privileged access to object representations, so objects are accessed and created according to their public APIs. As a result, serializations from older versions where the internal representation has changed can still be read as long as the public API is still available.
The way an object's state is read and written is defined by SerializationRules. These can be implemented in various ways. The easiest to use is using mirrors to find the members. Rules can also be hand-written or, for relatively simple classes, generated using a transformer.
depending on whether or not you want the mirrored rules. These are more convenient, but cause increased code size in dartj2s.
To use the transformer, include something in the pubspec like
transformers: - serialization : $include: ["lib/stuff.dart", "lib/more_stuff.dart"]
Then, set up the generated rules in a Serialization instance, and then call
write(). The serialization rules will be named as
the name of the model file with
_serialization_rules appended to it,
so in the case of
the same directory as the original.
Normally you won't ever see these files, because the
transformer creates it on the fly and it is sent directly to pub serve
or to dart2js without ever being written to disk.
To see the generated code, run pub build in debug mode, e.g.
if there is a program in the package's
bin directory to run something
using these files, then
pub build --mode=debug bin
would generate the code for that, and also log which files were generated, in the form
Generated serialization rules in my_package|lib/stuff_serialization_rules.dart
It's also possible to run the transformer's code outside of the transformer, which is helpful for debugging or to use the code in a different way. See the `test/transformer/generate_standalone.dart' for an example of that.
The bin directory code would look something like.
import 'package:my_package/stuff_serialization_rules.dart' as foo; ... var serialization = new Serialization(); foo.rules.values.forEach(serialization.addRule); ... sendToClient(serialization.write(somePerson));
and on the client, do something like
p = readFromServer(personId).then((data) => serialization.read(data));
Alternatively, if using the mirrored rules, just tell the serialization which classes might be serialized.
var serialization = new Serialization() ..addRuleFor(Person); ..addRuleFor(Address); serialization.write(address);
For more concrete examples, see the
test directory, and particularly
for examples of the transformer it may be useful to look at the
pubspec.yaml for this package, and the
Requests and bugs #
This is not an official Google project.
- Update to use test. Otherwise the bot runner fails.
- Fix tests to deal with DateTimes on the VM using microseconds.
- Update prerequisites and .gitignore.
- Added path package dependency (used in transformer).
- Fix to handle null keys in maps.
Clean up setup for serialization. Adds
defaultFormat, and a named
formatparameter to the constructors to set
Improved the README.
Fixes for transformer when generating maps, test that option properly.
- Adds a transformer that can generate serialization rules for simple classes.
- BREAKING CHANGE: serialization.dart no longer imports dart:mirrors by default. If you want mirrors, import serialization_mirrors.dart instead. Note that the default ordering of rules has also changed, because the non-mirrored version no longer includes SymbolRule, so even in the mirrored version it occurs later in the order. So even if you are still using mirrors, data serialized using an older version with default rule setup may not deserialize in this version. If you need to do this, you can explicitly create a Serialization instance with the old numbering.
Use this package as a library
1. Depend on it
Add this to your package's pubspec.yaml file:
dependencies: serialization: ^0.10.4+4
2. Install it
You can install packages from the command line:
$ pub get
Alternatively, your editor might support
Check the docs for your editor to learn more.
3. Import it
Now in your Dart code, you can use:
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Analysis issues and suggestions
Support Dart 2 in
The SDK constraint in
pubspec.yaml doesn't allow the Dart 2.0.0 release. For information about upgrading it to be Dart 2 compatible, please see https://dart.dev/dart-2#migration.
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