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Codecs are a serialization tool from mojang's DataFixerUpper library. Codecs are used alongside [[DynamicOps|DynamicOps]] to allow objects to be serialized to different formats and back, such as JSON or [[Using_NBT|NBT]]. While the DynamicOps describes the format the object is to be serialized to, the Codec describes the manner in which the object is to be serialized; a single Codec can be used to serialize an object to any format for which a DynamicOps exists. Codecs and DynamicOps jointly form an abstraction layer over data serialization, simplifying the effort needed to serialize or deserialize data.

Codecs are a serialization tool from mojang's DataFixerUpper library. Codecs are used alongside [[DynamicOps|DynamicOps]] to allow objects to be serialized to different formats and back, such as JSON or [[Using_NBT|NBT]]. While the DynamicOps describes the format the object is to be serialized to, the Codec describes the manner in which the object is to be serialized; a single Codec can be used to serialize an object to any format for which a DynamicOps exists. Codecs and DynamicOps jointly form an abstraction layer over data serialization, simplifying the effort needed to serialize or deserialize data.

=Using Codecs=

= Using Codecs =

==Serialization and Deserialization==

 

The primary use for Codecs is to serialize java objects to some serialized type, such as a JsonElement or a Tag, and to deserialize a serialized object back to its proper java type. This is accomplished with <code>Codec#encodeStart</code> and <code>Codec#parse</code>, respectively. Given a Codec<somejavatype> and a DynamicOps<someserializedtype>, we can convert instances of SomeJavaType to instances of SomeSerializedType and back.

== Serialization and Deserialization ==

 

The primary use for Codecs is to serialize java objects to some serialized type, such as a JsonElement or a Tag, and to deserialize an serialized object back to its proper java type. This is accomplished with <code>Codec#encodeStart</code> and <code>Codec#parse</code>, respectively. Given a Codec<SomeJavaType> and a DynamicOps<SomeSerializedType>, we can convert instances of SomeJavaType to instances of SomeSerializedType and back.

Each of these methods take a [[DynamicOps]] instance and an instance of the object we are serializing or deserializing, and returns a DataResult:

Each of these methods take a [[DynamicOps]] instance and an instance of the object we are serializing or deserializing, and returns a DataResult:

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== Builtin Codecs ==

==Builtin Codecs==

=== Primitive Codecs ===

===Primitive Codecs===

The Codec class itself contains static instances of codecs for all supported primitive types, e.g. <code>Codec.STRING</code> is the canonical <code>Codec<String></code> implementation. Primitive codecs include:

The Codec class itself contains static instances of codecs for all supported primitive types, e.g. <code>Codec.STRING</code> is the canonical <code>Codec<string></string></code> implementation. Primitive codecs include:

* BOOL, which serializes to a boolean value

* BOOL, which serializes to a boolean value

* BYTE, SHORT, INT, LONG, FLOAT, and DOUBLE, which serialize to numeric values

* BYTE, SHORT, INT, LONG, FLOAT, and DOUBLE, which serialize to numeric values

* EMPTY, which represents null objects

* EMPTY, which represents null objects

===Other Builtin Codecs===

=== Other Builtin Codecs ===

Vanilla minecraft has many builtin codecs for objects that it frequently serializes. These codecs are typically static instances in the class the codec is serializing; e.g. <code>ResourceLocation.CODEC</code> is the canonical <code>Codec<resourcelocation></resourcelocation></code>, while <code>BlockPos.CODEC</code> is the codec used for serializing a BlockPos.

Vanilla minecraft has many builtin codecs for objects that it frequently serializes. These codecs are typically static instances in the class the codec is serializing; e.g. <code>ResourceLocation.CODEC</code> is the canonical <code>Codec<ResourceLocation></code>, while <code>BlockPos.CODEC</code> is the codec used for serializing a BlockPos.

Each vanilla <code>Registry</code> acts as the Codec for the type of object the registry contains; e.g. <code>Registry.BLOCK</code> is itself a <code>Codec<block></block></code>. Forge Registries, however, do not currently implement Codec and cannot yet be used in this way; custom codecs must be created for forge-specific registries that are not tied to specific vanilla registries.

Each vanilla <code>Registry</code> acts as the Codec for the type of object the registry contains; e.g. <code>Registry.BLOCK</code> is itself a <code>Codec<Block></code>. Forge Registries, however, do not currently implement Codec and cannot yet be used in this way; custom codecs must be created for forge-specific registries that are not tied to specific vanilla registries.

Of particular note here is the CompoundTag.CODEC, which can be used to e.g. serialize a CompoundTag into a json file. This has a notable limitation in that CompoundTag.CODEC *cannot* safely deserialize lists of numbers from json, due to the strong typing of ListTag and the way that the NBTOps deserializer reads numeric values.

Of particular note here is the CompoundTag.CODEC, which can be used to e.g. serialize a CompoundTag into a json file. This has a notable limitation in that CompoundTag.CODEC *cannot* safely deserialize lists of numbers from json, due to the strong typing of ListTag and the way that the NBTOps deserializer reads numeric values.