-
Notifications
You must be signed in to change notification settings - Fork 49
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
* orgScriptCI task integration. Bumps sbt-org-policies integration. Brings back the readme to the tut folder. * Bumps to new version where badges are fixed
- Loading branch information
1 parent
da440e1
commit b088bdc
Showing
6 changed files
with
260 additions
and
18 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1 +1,2 @@ | ||
| addSbtPlugin("com.47deg" % "sbt-org-policies" % "0.4.12") | ||
| resolvers += Resolver.sonatypeRepo("releases") | ||
| addSbtPlugin("com.47deg" % "sbt-org-policies" % "0.4.18") |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,202 @@ | ||
|
|
||
| [comment]: # (Start Badges) | ||
|
|
||
| [](https://gitter.im/47deg/fetch?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [](https://travis-ci.org/47deg/fetch) [](http://codecov.io/github/47deg/fetch?branch=master) [](https://maven-badges.herokuapp.com/maven-central/com.47deg/fetch) [](https://raw.githubusercontent.com/47deg/fetch/master/LICENSE) [](https://index.scala-lang.org/47deg/fetch/fetch) [](https://github.com/47deg/fetch/issues) | ||
|
|
||
| [comment]: # (End Badges) | ||
|
|
||
| # Fetch | ||
|
|
||
| A library for Simple & Efficient data access in Scala and Scala.js | ||
|
|
||
| - [Documentation](http://47deg.github.io/fetch/docs) | ||
|
|
||
| ## Installation | ||
|
|
||
| Add the following dependency to your project's build file. | ||
|
|
||
| For Scala 2.11.x and 2.12.x: | ||
|
|
||
| [comment]: # (Start Replace) | ||
|
|
||
| ```scala | ||
| "com.47deg" %% "fetch" % "0.6.1" | ||
| ``` | ||
|
|
||
| Or, if using Scala.js (0.6.x): | ||
|
|
||
| ```scala | ||
| "com.47deg" %%% "fetch" % "0.6.1" | ||
| ``` | ||
|
|
||
| [comment]: # (End Replace) | ||
|
|
||
| ```tut:invisible | ||
| val out = Console.out | ||
| def println(msg: String): Unit = { | ||
| Console.withOut(out) { | ||
| Console.println(msg) | ||
| } | ||
| } | ||
| ``` | ||
|
|
||
| ## Remote data | ||
|
|
||
| Fetch is a library for making access to data both simple & efficient. Fetch is especially useful when querying data that | ||
| has a latency cost, such as databases or web services. | ||
|
|
||
| ## Define your data sources | ||
|
|
||
| To tell `Fetch` how to get the data you want, you must implement the `DataSource` typeclass. Data sources have `fetchOne` and `fetchMany` methods that define how to fetch such a piece of data. | ||
|
|
||
| Data Sources take two type parameters: | ||
|
|
||
| 1. `Identity` is a type that has enough information to fetch the data. For a users data source, this would be a user's unique ID. | ||
| 2. `Result` is the type of data we want to fetch. For a users data source, this would the `User` type. | ||
|
|
||
| ```scala | ||
| import cats.data.NonEmptyList | ||
|
|
||
| trait DataSource[Identity, Result]{ | ||
| def name: String | ||
| def fetchOne(id: Identity): Query[Option[Result]] | ||
| def fetchMany(ids: NonEmptyList[Identity]): Query[Map[Identity, Result]] | ||
| } | ||
| ``` | ||
|
|
||
| We'll implement a dummy data source that can convert integers to strings. For convenience, we define a `fetchString` function that lifts identities (`Int` in our dummy data source) to a `Fetch`. | ||
|
|
||
| ```tut:silent | ||
| import cats.data.NonEmptyList | ||
| import cats.instances.list._ | ||
| import fetch._ | ||
| implicit object ToStringSource extends DataSource[Int, String]{ | ||
| override def name = "ToString" | ||
| override def fetchOne(id: Int): Query[Option[String]] = { | ||
| Query.sync({ | ||
| println(s"[${Thread.currentThread.getId}] One ToString $id") | ||
| Option(id.toString) | ||
| }) | ||
| } | ||
| override def fetchMany(ids: NonEmptyList[Int]): Query[Map[Int, String]] = { | ||
| Query.sync({ | ||
| println(s"[${Thread.currentThread.getId}] Many ToString $ids") | ||
| ids.toList.map(i => (i, i.toString)).toMap | ||
| }) | ||
| } | ||
| } | ||
| def fetchString(n: Int): Fetch[String] = Fetch(n) // or, more explicitly: Fetch(n)(ToStringSource) | ||
| ``` | ||
|
|
||
| ## Creating and running a fetch | ||
|
|
||
| Now that we can convert `Int` values to `Fetch[String]`, let's try creating a fetch. | ||
|
|
||
| ```tut:silent | ||
| import fetch.syntax._ | ||
| val fetchOne: Fetch[String] = fetchString(1) | ||
| ``` | ||
|
|
||
| We'll run our fetches to the ambien `Id` monad in our examples. Note that in real-life scenarios you'll want to run a fetch to a concurrency monad such as `Future` or `Task`, synchronous execution of a fetch is only supported in Scala and not Scala.js and is meant for experimentation purposes. | ||
|
|
||
| ```tut:silent | ||
| import cats.Id | ||
| import fetch.unsafe.implicits._ | ||
| import fetch.syntax._ | ||
| ``` | ||
|
|
||
| Let's run it and wait for the fetch to complete: | ||
|
|
||
| ```tut:book | ||
| fetchOne.runA[Id] | ||
| ``` | ||
|
|
||
| ## Batching | ||
|
|
||
| Multiple fetches to the same data source are automatically batched. For illustrating it, we are going to compose three independent fetch results as a tuple. | ||
|
|
||
| ```tut:silent | ||
| import cats.syntax.cartesian._ | ||
| val fetchThree: Fetch[(String, String, String)] = (fetchString(1) |@| fetchString(2) |@| fetchString(3)).tupled | ||
| ``` | ||
|
|
||
| When executing the above fetch, note how the three identities get batched and the data source is only queried once. | ||
|
|
||
| ```tut:book | ||
| fetchThree.runA[Id] | ||
| ``` | ||
|
|
||
| ## Parallelism | ||
|
|
||
| If we combine two independent fetches from different data sources, the fetches can be run in parallel. First, let's add a data source that fetches a string's size. | ||
|
|
||
| This time, instead of creating the results with `Query#sync` we are going to do it with `Query#async` for emulating an asynchronous data source. | ||
|
|
||
| ```tut:silent | ||
| implicit object LengthSource extends DataSource[String, Int]{ | ||
| override def name = "Length" | ||
| override def fetchOne(id: String): Query[Option[Int]] = { | ||
| Query.async((ok, fail) => { | ||
| println(s"[${Thread.currentThread.getId}] One Length $id") | ||
| ok(Option(id.size)) | ||
| }) | ||
| } | ||
| override def fetchMany(ids: NonEmptyList[String]): Query[Map[String, Int]] = { | ||
| Query.async((ok, fail) => { | ||
| println(s"[${Thread.currentThread.getId}] Many Length $ids") | ||
| ok(ids.toList.map(i => (i, i.size)).toMap) | ||
| }) | ||
| } | ||
| } | ||
| def fetchLength(s: String): Fetch[Int] = Fetch(s) | ||
| ``` | ||
|
|
||
| And now we can easily receive data from the two sources in a single fetch. | ||
|
|
||
| ```tut:silent | ||
| val fetchMulti: Fetch[(String, Int)] = (fetchString(1) |@| fetchLength("one")).tupled | ||
| ``` | ||
|
|
||
| Note how the two independent data fetches run in parallel, minimizing the latency cost of querying the two data sources. | ||
|
|
||
| ```tut:book | ||
| fetchMulti.runA[Id] | ||
| ``` | ||
|
|
||
| ## Caching | ||
|
|
||
| When fetching an identity, subsequent fetches for the same identity are cached. Let's try creating a fetch that asks for the same identity twice. | ||
|
|
||
| ```tut:silent | ||
| val fetchTwice: Fetch[(String, String)] = for { | ||
| one <- fetchString(1) | ||
| two <- fetchString(1) | ||
| } yield (one, two) | ||
| ``` | ||
|
|
||
| While running it, notice that the data source is only queried once. The next time the identity is requested it's served from the cache. | ||
|
|
||
| ```tut:book | ||
| fetchTwice.runA[Id] | ||
| ``` | ||
| ## Fetch in the wild | ||
|
|
||
| If you wish to add your library here please consider a PR to include it in the list below. | ||
|
|
||
| [comment]: # (Start Copyright) | ||
|
|
||
| # Copyright | ||
|
|
||
| Fetch is designed and developed by 47 Degrees | ||
|
|
||
| Copyright (C) 2016-2017 47 Degrees. <http://47deg.com> | ||
|
|
||
| [comment]: # (End Copyright) |