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resolves #99 easier projection for one, two or three fields
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178 changes: 178 additions & 0 deletions
178
kmongo-shared/src/main/kotlin/org/litote/kmongo/util/Projections.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,178 @@ | ||
| /* | ||
| * Copyright (C) 2017/2018 Litote | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| package org.litote.kmongo.util | ||
|
|
||
| import org.bson.BsonReader | ||
| import org.bson.BsonWriter | ||
| import org.bson.codecs.Codec | ||
| import org.bson.codecs.DecoderContext | ||
| import org.bson.codecs.EncoderContext | ||
| import org.bson.codecs.configuration.CodecRegistries | ||
| import org.bson.codecs.configuration.CodecRegistry | ||
|
|
||
| /** | ||
| * Single projection (one field only). | ||
| */ | ||
| class SingleProjection<F>(val field: F?) | ||
|
|
||
| /** | ||
| * Pair projection (two fields). | ||
| */ | ||
| class PairProjection<F1, F2>(val field1: F1?, val field2: F2?) | ||
|
|
||
| /** | ||
| * Triple projection (three fields). | ||
| */ | ||
| class TripleProjection<F1, F2, F3>(val field1: F1?, val field2: F2?, val field3: F3?) | ||
|
|
||
| /** | ||
| * This method is not part of the public API and may be removed or changed at any time. | ||
| */ | ||
| inline fun <reified T> singleProjectionCodecRegistry( | ||
| baseRegistry: CodecRegistry | ||
| ): CodecRegistry { | ||
| return CodecRegistries.fromRegistries( | ||
| CodecRegistries.fromCodecs( | ||
| object : Codec<SingleProjection<*>> { | ||
| override fun getEncoderClass(): Class<SingleProjection<*>> = SingleProjection::class.java | ||
|
|
||
| override fun encode( | ||
| writer: BsonWriter, | ||
| value: SingleProjection<*>, | ||
| encoderContext: EncoderContext | ||
| ) { | ||
| error("not supported") | ||
| } | ||
|
|
||
| override fun decode(reader: BsonReader, decoderContext: DecoderContext): SingleProjection<*> { | ||
| reader.readStartDocument() | ||
| reader.readName() | ||
| val codec = baseRegistry.get(T::class.java) | ||
| val r = codec.decode(reader, decoderContext) | ||
| reader.readEndDocument() | ||
| return SingleProjection(r) | ||
| } | ||
| } | ||
| ), | ||
| baseRegistry | ||
| ) | ||
| } | ||
|
|
||
| /** | ||
| * This method is not part of the public API and may be removed or changed at any time. | ||
| */ | ||
| inline fun <reified T1, reified T2> pairProjectionCodecRegistry( | ||
| property1: String, | ||
| property2: String, | ||
| baseRegistry: CodecRegistry | ||
| ): CodecRegistry { | ||
| return CodecRegistries.fromRegistries( | ||
| CodecRegistries.fromCodecs( | ||
| object : Codec<PairProjection<*, *>> { | ||
| override fun getEncoderClass(): Class<PairProjection<*, *>> = PairProjection::class.java | ||
|
|
||
| override fun encode( | ||
| writer: BsonWriter, | ||
| value: PairProjection<*, *>, | ||
| encoderContext: EncoderContext | ||
| ) { | ||
| error("not supported") | ||
| } | ||
|
|
||
| override fun decode(reader: BsonReader, decoderContext: DecoderContext): PairProjection<*, *> { | ||
| reader.readStartDocument() | ||
| var r1: T1? = null | ||
| var r2: T2? = null | ||
| try { | ||
| while (r1 == null || r2 == null) | ||
| when (reader.readName()) { | ||
| property1 -> { | ||
| val codec1 = baseRegistry.get(T1::class.java) | ||
| r1 = codec1.decode(reader, decoderContext) | ||
| } | ||
| property2 -> { | ||
| val codec2 = baseRegistry.get(T2::class.java) | ||
| r2 = codec2.decode(reader, decoderContext) | ||
| } | ||
| } | ||
| } catch (e: Exception) { | ||
| //ignore | ||
| } | ||
| reader.readEndDocument() | ||
| return PairProjection(r1, r2) | ||
| } | ||
| } | ||
| ), | ||
| baseRegistry | ||
| ) | ||
| } | ||
|
|
||
| /** | ||
| * This method is not part of the public API and may be removed or changed at any time. | ||
| */ | ||
| inline fun <reified T1, reified T2, reified T3> tripleProjectionCodecRegistry( | ||
| property1: String, | ||
| property2: String, | ||
| property3: String, | ||
| baseRegistry: CodecRegistry | ||
| ): CodecRegistry { | ||
|
|
||
| return CodecRegistries.fromRegistries( | ||
| CodecRegistries.fromCodecs( | ||
| object : Codec<TripleProjection<*, *, *>> { | ||
| override fun getEncoderClass(): Class<TripleProjection<*, *, *>> = TripleProjection::class.java | ||
|
|
||
| override fun encode( | ||
| writer: BsonWriter, | ||
| value: TripleProjection<*, *, *>, | ||
| encoderContext: EncoderContext | ||
| ) { | ||
| error("not supported") | ||
| } | ||
|
|
||
| override fun decode(reader: BsonReader, decoderContext: DecoderContext): TripleProjection<*, *, *> { | ||
| reader.readStartDocument() | ||
| var r1: T1? = null | ||
| var r2: T2? = null | ||
| var r3: T3? = null | ||
| try { | ||
| while (r1 == null || r2 == null || r3 == null) | ||
| when (reader.readName()) { | ||
| property1 -> { | ||
| val codec1 = baseRegistry.get(T1::class.java) | ||
| r1 = codec1.decode(reader, decoderContext) | ||
| } | ||
| property2 -> { | ||
| val codec2 = baseRegistry.get(T2::class.java) | ||
| r2 = codec2.decode(reader, decoderContext) | ||
| } | ||
| property3 -> { | ||
| val codec3 = baseRegistry.get(T3::class.java) | ||
| r3 = codec3.decode(reader, decoderContext) | ||
| } | ||
| } | ||
| } catch (e: Exception) { | ||
| //ignore | ||
| } | ||
| reader.readEndDocument() | ||
| return TripleProjection(r1, r2, r3) | ||
| } | ||
| } | ||
| ), | ||
| baseRegistry | ||
| ) | ||
| } |