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Kotlin 协程

快速参考

本页面展示了多个 MongoDB 命令的驱动语法以及它们相关的参考和 API 文档链接。

页面上的示例使用了以下数据类来表示 MongoDB 文档

data class Movie(
    val title: String,
    val year: Int,
    val rated: String? = "Not Rated",
    val genres: List<String>? = listOf()
)
命令
语法
查找文档

API 文档
使用示例
基础知识
collection.find(
    Filters.eq(Movie::title.name, "Shrek")
).firstOrNull()
Movie(title=Shrek, year=2001, ...)
collection.find(
    Filters.eq(Movie::year.name, 2004)
)
[
 Movie(title=Shrek 2, year=2004, ...),
 Movie(title=Spider-Man 2, year=2004, ...),
 Movie(title=National Treasure, year=2004, ...),
 ...
]
collection.insertOne(Movie("Shrek", 2001))
collection.insertMany(
    listOf(
        Movie("Shrek", 2001),
        Movie("Shrek 2", 2004),
        Movie("Shrek the Third", 2007),
        Movie("Shrek Forever After", 2010),
    )
)
collection.updateOne(
    Filters.eq(Movie::title.name, "Shrek"),
    Updates.set(Movie::rated.name, "PG")
)
Movie(title=Shrek, year=2001, rated=PG, genres=[])
collection.updateMany(
    Filters.regex(Movie::title.name, "Shrek"),
    Updates.set(Movie::rated.name, "PG")
)
[
  Movie(title=Shrek, year=2001, rated=PG, genres=[]),
  Movie(title=Shrek 2, year=2004, rated=PG, genres=[]),
  Movie(title=Shrek the Third, year=2007, rated=PG, genres=[]),
  Movie(title=Shrek Forever After, year=2010, rated=PG, genres=[])
]
更新文档中的数组

API 文档
基础知识
collection.updateOne(
    Filters.eq(Movie::title.name, "Shrek"),
    Updates.addEachToSet(Movie::genres.name, listOf("Family", "Fantasy"))
)
Movie(title=Shrek, year=2001, rated=Not Rated, genres=[Family, Fantasy])
collection.replaceOne(
    Filters.eq(Movie::title.name, "Shrek"),
    Movie("Kersh", 1002, "GP")
)
Movie(title=Kersh, year=1002, rated=GP, genres=[])
collection.deleteOne(
    Filters.eq(Movie::title.name, "Shrek")
)
collection.deleteMany(
    Filters.regex(Movie::title.name, "Shrek")
)
collection.bulkWrite(
    listOf(
        InsertOneModel(Movie("Shrek", 2001)),
        DeleteManyModel(Filters.lt(Movie::year.name, 2004)),
    )
)
val changeStream = collection.watch()
changeStream.collect {
    println("Change to ${it.fullDocument?.title}")
}
将查询结果作为列表访问
collection.find().toList()
[
  Movie(title=Shrek, year=2001, rated=Not Rated, genres=[]),
  Movie(title=Shrek 2, year=2004, rated=Not Rated, genres=[]),
  Movie(title=Shrek the Third, year=2007, rated=Not Rated, genres=[]),
  Movie(title=Shrek Forever After, year=2010, rated=Not Rated, genres=[])
]
collection.countDocuments(Filters.eq("year", 2001))
42
列出不同的文档或字段值
API 文档
使用示例
collection.distinct<String>(Movie::rated.name)
[Not Rated, PG, PG-13]
限制检索的文档数量

API 文档
基础知识
collection.find()
    .limit(2)
[
  Movie(title=Shrek, year=2001, rated=Not Rated, genres=[]),
  Movie(title=Shrek 2, year=2004, rated=Not Rated, genres=[])
]
跳过检索的文档

API 文档
基础知识
collection.find()
    .skip(2)
[
  Movie(title=Shrek the Third, year=2007, rated=Not Rated, genres=[]),
  Movie(title=Shrek Forever After, year=2010, rated=Not Rated, genres=[])
]
在检索时对文档进行排序

API 文档
基础知识
collection.find().sort(Sorts.descending(Movie::year.name))
[
  Movie(title=Shrek Forever After, year=2010, rated=Not Rated, genres=[]),
  Movie(title=Shrek the Third, year=2007, rated=Not Rated, genres=[]),
  Movie(title=Shrek 2, year=2004, rated=Not Rated, genres=[]),
  Movie(title=Shrek, year=2001, rated=Not Rated, genres=[])
]
在检索时投影文档字段

API 文档
使用示例
基础知识
data class Result(val title: String)
    collection.find<Result>()
        .projection(Projections.include(Movie::title.name))
Result(title=Shrek)
collection.createIndex(Indexes.ascending(Movie::title.name))
collection.find(Filters.text("Forever"));
[Movie(title=Shrek Forever After, year=2010, rated=Not Rated, genres=[])]
使用Maven安装驱动依赖
pom.xml
<dependencies>
    <dependency>
        <groupId>org.mongodb</groupId>
        <artifactId>mongodb-driver-kotlin-coroutine</artifactId>
        <version>5.2.1</version>
    </dependency>
</dependencies>
使用Gradle安装驱动依赖
build.gradle.kts
dependencies {
    implementation("org.mongodb:mongodb-driver-kotlin-coroutine:5.2.1")
}
迭代地从流中访问数据

API 文档
基础知识
val flow = collection.find(
    Filters.eq(Movie::year.name, 2004)
)
flow.collect { println(it) }
Movie(title=2001: A Space Odyssey, ...)
Movie(title=The Sound of Music, ...)

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