Spark streaming files from a directory spark by examples. When program execution pauses, copymove the files to a folder. For instructions on running and using the project, please see the appendix. For instance, a user can now say check stock prices, get stock prices, or get stocks to check their stocks. However, one of the things i need is the uri associated with the attribute in the array element that has rel.
As shown in the previous recipe, this isnt necessary for simple objects, but it is necessary once objects become more complex, specifically once they contain collections. Lift cookbook a community question and answers book, free at cookbook lift web applications howto by torsten uhlmann is available in print and ebook format. You need to parse these files and combine the data in two files to check how many asset impressions, views and clicks are present in both the files for each page view id. This action expects a request with a contenttype header of text json or application json and a body containing a json representation of the entity to create.
This recipe demonstrates the lift json and gson libraries. Recipes from the community for building web applications with scala 20 by richard dallaway. It uses a json specific bodyparser which will parse the request and provide request. Mapping associations with couchdb, scala and lift dzone java. To do this, i added an array of phrases to the json file that describes the stocks plugin. This is good for pattern matching when you want to change behaviour based on the suffix, but a hindrance in this particular situation. This example is in scala, but play also has a java api which looks and acts just like the scala api, and has a corresponding playjavarestapi example project in the playsamples repo. If you want you can also download the sbt plugin for idea. Create spark project in scala with eclipse without maven.
Use scastie to run singlefile scala programs in your browser using multiple scala compilers. This step by step tutorial will explain how to create a spark project in scala with eclipse without maven and how to submit the application after the creation of jar. The operator in the first example transforms tuples in jfields combining them in a list to create a org. The lift json json parser in liftweb does a good job, too, but returns jobjectlike types instead of raw string or mapstring, object. If you simply want to use lift in your project, add lift as a dependency to your build system or download the jar files directly. A central concept in lift json library is json ast which models the structure of a json document as a syntax tree. Lift open source software licensed under an apache 2. Reading csvexcel files, sorting, filtering, groupby duration. As i continue to plug away on my computer voice control. You should see the output on console and refreshes as you move the files to a folder. Lift json provides several different styles to extract data from json. Its very useful to be familiar with this data type since its how circe models the base type we want to address. Java project tutorial make login and register form step by step using netbeans and mysql database duration.
While both encoders and standard serialization are responsible for turning an object into bytes, encoders are code generated dynamically and use a format that allows spark to. It turns out that the situation is similar if not worse. Please see more examples in srctestscala netliftwebjsonqueryexamples. One of the things im doing here is to parse some of the json text into an array of objects, in this case an array of string objects. Json4s is a port of lift json, so it shares the same api. Datasets getting started with apache spark on databricks.
Lift in action by tim perrett is available in print and ebook format. Now that we know how to load a json in scala, lets give few simple example about how to manipulate it. The following code shows a complete example of how to use liftjson to convert a json string into a case class named mailserver. Im parsing the document using lift json btw, congratulations on a great library. First, for primitive types in examples or demos, you can create datasets within a scala or python notebook or in your sample spark application. Scala how to download url contents to a string or file. When using foreign key association mapping in a relational database using lift s mapper framework or javas jpa for example, the framework will automatically manage the association object, so. The lift json library uses its own dsl for generating json output from scala objects. I ran a few tests last night in the scala repl to see if i could think of different ways to download the contents of a url to a string or file in scala, and came up with a couple of different solutions, which ill share here.
Liftweb setup in 10 minutes ide and project configuration dzone. Dzone java zone mapping associations with couchdb, scala and lift. To begin, lets briefly talk about the shape of every json object. Its basically semistructured data built on top of keyvalue pairs. To create a new, basic lift application that has some example code, simply execute. We used the validate method for conversion which will rely on our implicit readsplace. The simply functional web framework for scala 2011 by timothy perrett. This page assumes youve installed sbt 1 lets start with examples rather than explaining how sbt works or why. What is the scalarific way to grab a value out of this json.
Deploying a scala lift application in an osgi container. Published on 6 november 2015, last updated on 6 june 2018. This guide also briefs about the installation of scala plugin in eclipse and setup spark environment in eclipse. Using json with play and scala using json with javas play framework and scala is a natural fit. These examples are extracted from open source projects. Read on to find out how you can enable and use json in your next play project. The complete example code can be found in the github download it and run sparkstreamingfromdirectory. Instant lift web applications 20 by torsten uhlmann. Scala json features and performance linkedin slideshare. Running and debugging the lift project in scala ide.
With macports, you can get scala using sudo port install scala2. Here are some urls i used to get the correct lift json jar. The examples repository contains the source code for several example lift applications, including demo building lift. Simple example of processing twitter json payload from a. Learn how to configure development environment for developing. The following example demonstrates how to deserialize the string jsonstring into a series of. Parameter weight added to overloaded version of shortestpathto to enable flexible weight definitions. This functionality depends on a converter of type writest which can convert a t to a jsvalue. It provides a case class for each of the above mentioned json.
First, heres the scala source code for my example, and then a description will follow. Let me strongly suggest jawn, which supports streaming json parsing using any of a variety of asts. Read an overview of how lift achieves these important goals. Lift web framework minimal rest api example example. Because lift applications are written in scala, an elegant jvm language, you can still use your favorite java libraries and deploy to your favorite servlet container and app server. Native deserialization 940 ms based on the lift web framework json parser jackson deserialization 670 ms. How to convert xml array to json data in scala tag. Scala is one of the coolest programming languages out there and lift is a. Now lets take a look at how our example from javas stream extensibility, behaves using seq by joo. This simple json example is based on a morecomplicated json example here at. Json is the circe data type representing a json object. A central concept in lift json library is json ast abstract syntax tree which models the structure of a json document as a syntax tree.
As its name implies, mailserver represents the information an email client needs to connect to a server. How can i parse json text or a json document with scala. Almost the simplest possible play framework and scala. If youre familiar with the play framework, youll know that its common to use a wrapper template around other templates to keep the look and feel of a website consistent. Use the lift json library to convert a json string to an instance of a case class. A quick tour of json libraries in scala manuel bernhardt. We speak with matt cutts about leading the united states digital services and the role software can play in government.
This is referred to as deserializing the string into an object. Resthelper resthelper is a trait provided by lift web framework, which let us create rest api in a simple and beautiful way there are already lots of example of resthelper, but i feel most of those example a little bit long, so ive created a really minimal json rest api of a blog article, which support get post and delete request. Jul 31, 2016 learn how to read json as file in scala. Datasets are similar to rdds, however, instead of using java serialization or kryo they use a specialized encoder to serialize the objects for processing or transmitting over the network. If the json maps directly to a class, we provide a handy macro so that you dont have to write the readst, writest, or formatt manually. Working with json in scala using the json4s library part.
Getting to the point of this post, the following scala source code shows how to read an array of json string values using lift json. Graph for scala json is supplied as an extra module jar. David suggested lift and scala and initial testing proved that we could realize the developer efficiency and backend scalability that we felt was required to. Lift application development cookbook by gilberto t. Xml how to convert xml array to json data in scala.
How do i download the contents of a url to a string or file in scala. Creating a simple scala object from a json string oreilly. Parsing json problem with files greater than 100mb. A very promising project started by the guys from wordnik of swagger fame, it aims to unify scala json asts, sports multiple backends including jackson, and has native support from both scalatra and spray. While navigating json tree, you retrieve jsvalue, however you may want to convert the jsvalue to a scala type. Apache spark sql loading and saving data using the json. The play json api provides implicit writes for most basic types, such as int, double, string, and boolean. To add the xsbtwebplugin download the most recent version of our. For example, you may want a jsstring to be converted to a string, or a jsnumber to be converted to a long. To demonstrate the lift json library, create an empty sbt test project.
Most examples in the following chapters are based on a partial academic library application backed by a graph. Rest this chapter looks at recipes around rest web services, via lifts resthelper trait. Finally figured this out after breaking my head over numerous scala json libraries that are not as performant or reliable as jackson. Parsing json data into an array of objects problem you have a json string that represents an array of objects, and you need to deserialize it into objects you selection from scala cookbook book. Since you are familiar with lift json, you may wish to use json4s native module, which is literally just lift json repackaged. Try to add some cool things with new features of scala 2. When lift parses a request, it splits the request into constituent parts e. Nested arrays, elements at varying levels, inconsistent fields, requirements for string manipulation, etc. Mapping associations with couchdb, scala and lift by aleksa vukotic. Scala to jsvalue conversion is performed by the utility method json.
For example, heres a way to create a dataset of 100 integers in a notebook. Because lift applications are written in scala, an elegant jvm language, you can. Jobject, while using the parse function, it will return a org. In particular, im trying to parse a json document into scala objects, and im using lift json to do so. The easiest way to deploy a war file is using pax webs war extender. Lift application development cookbook 20 by gilberto t. Parsing json data into an array of objects scala cookbook. Would have saved me a day or two of trying them all out especially play json and json4s if had found this earlier. The following code shows a complete example of how to use lift json to convert a json string into a case class named mailserver. Use a combination of methods from the liftjson library. Finding correct jar file to work with scala example stack overflow. You can use json4s, which usually works exactly the same as lift. Returning json gives an example of accepting and returning json.