Scala dispatch json example in android

Working with json in scala using the json4s library part two. How to page rest calls in a future with dispatch and scala. Fortunately, with the lift json dsl you can break your json generating code down into small chunks to keep the code maintainable. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the. Writing json generating code like this feels just like writing other scala code. If you want to learn scala on android and you want to share your examples, you can send us a pr with your new feature. Test whether the dynamic type of the receiver object is t0 note that the result of the test is modulo scalas erasure semantics. Contribute to 47degscala android development by creating an account on github. While navigating json tree, you retrieve jsvalue, however you may want to convert the jsvalue to a scala type. If it doesnt matter that your web service client wont time out in a controlled manner, you can use this simple method to download the contents from a url. Sep 18, 2012 luckily, its easy to create a better and faster parser. Scala working with rest service calls and handling json. Finally figured this out after breaking my head over numerous scala json libraries that are not as performant or reliable as jackson. I made this repository because i had a lot of trouble getting the dev environment set up for android development with scala even though the guides i did follow definitely helped.

Mediamath scala json compiletime json marshaling and abstraction for scala, scala native and scala. These solutions are demonstrated in the following sections. Create a json object string with gson and scala or java. Simple examples a list of simple scala snippets, useful to understand some basics of. Scala on android preparing the environment 47 degrees. The post request works fine for sure since i tested it using curl. Feb 29, 2020 spray json uses sjsons scala idiomatic typeclassbased approach to connect an existing type t with the logic how to deserialize its instances to and from json. This is an excerpt from the scala cookbook partially modified for the internet.

This functionality depends on a converter of type writest which can convert a t to a jsvalue. Scalapb can convert protocol buffers to and from json, using json4s. Published on 6 november 2015, last updated on 6 june 2018. We were working on a spark job to read json files out of hdfs, and it seemed to be running way too slowly. Scala can be used to build android applications, as an alternative to java or kotlin. Ive read that the lift json library is best for android apps, so im using dispatch lift json. In the following example, the gson library is used to construct a json string, which is. Scala to jsvalue conversion is performed by the utility method json. We used the validate method for conversion which will rely on our implicit readsplace. Fwiw, heres an old approach i used to retrieve rest content content from a rest url. Read on to find out how you can enable and use json in your next play project. How to parse json in android example in this android code snippet tutorial, we are going to learn how to parse json in android application development. Theres a nice addon module for jackson to support scala data types. Ruby python javascript frontend tools ios php android.

These examples are extracted from open source projects. Gson this is the rough equivalent of a java pojo class. I define a string named json, which contains my json content. This method converts a standard dispatch request, which you have from. So, here are some notes to help others navigate the scala json parsing landscape, where there are at least 6 different libraries on both performance and correctness. Unlike them, setting up an android project in scala with sbt is not straightforward, and can give us. I read in the xml as in the previous tutorial and then use jerkson to generate the json without the. The benefit of this approach is that both the java and the scala side of play can share the same underlying library jackson, while scala users can. Crockford angry, you could maybe make a recursive function that pattern match against the json structures and do depthfirst traversal and returning the xml node on the function call. Luckily, its easy to create a better and faster parser. Ive read that the liftjson library is best for android apps, so im using dispatchliftjson. Scala libraries and wrappers for android development.

I used the jsonsmart cache library to do the actual parsing its really fast. Converting a nested json document to csv using scala. Unlike those options, setting up an android project in scala with sbt is not straightforward and can give us. Scala to jsvalue conversion is performed by the utility method jsonttimplicit writes. Easily update selected elements of the immutable sprayjson representation. In our simple example, we only need the androidsdkplugin, an sbt plugin developed by perry nguyen that works flawlessly with scala on android. In order to make steps 3 and 4 work for an object of type t you need to bring implicit values in scope that provide jsonformatt instances for t and all types used by t directly or indirectly. I made this repository because i had a lot of trouble getting the dev environment set up for android development with scala even though the. For example, you may want a jsstring to be converted to a string, or a jsnumber to be converted to a long. When writing scala code, you want to send json data or other data to a. You can find the scala cookbook at these locations. Working with json in scala using the json4s library part. I used the json smart cache library to do the actual parsing its really fast. In this example well leverage a web service to write an internal api that will tell us the temperature.

Would have saved me a day or two of trying them all out especially play json and json4s if had found this earlier. I think that theres a way to extract json values neatly, but ive read the code and cant figure it out. Working with json in scala using the json4s library part two in this second part this is the link to the first part we are going to delve deeper in the function offered by the library json4s. Let me start by saying that im not a developer or a contributor of json4s, im just an user that wanted to report this library on an article, in. Create queries similar to xpath in a native scala dsl. Dynamic cache which allows us to handle arbitrary method calls. Follow part a of the guide, then open up the project, or follow both part a and part b to make a project from scratch. Nowadays nearly all rest endpoints use json responses.

Converting a nested json document to csv using scala, hadoop, and apache spark posted on feb, 2017 at 6. Json uses javascript syntax, but the json format is text only, just like xml. It uses a json specific bodyparser which will parse the request and provide request. When writing scala code, you want to send json data or other data to a post url, either from a standalone client, or when using a framework that doesnt provide this type of service. Jun 23, 2015 working with json in scala using the json4s library part two in this second part this is the link to the first part we are going to delve deeper in the function offered by the library json4s. So, here are some notes to help others navigate the. Text can be read and used as a data format by any programming language. The play json api provides implicit writes for most basic types, such as int, double, string, and boolean. Using json with play and scala using json with javas play framework and scala is a natural fit. It provides a scala vocabulary for javas asyncclient. I parseextract that json string into an instance of my mailserver class. You want to generate a json representation of a scala object that contains one or more collections, such as a person class that has a list of friends or addresses.

Unlike them, setting up an android project in scala with sbt is not straightforward, and can give us some headaches to get it right. The package for a feature contains all of the ui information its not necessary but you should consider it. By the time of the announcement, i had already transitioned roughly 75% of lucids android app from kotlin to scala and have since moved to 100% scala. Post request with json in dispatch and scala stack overflow. 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. Im having trouble making a post request with a json object using dispatch and scala. Please note that the json support is done by specifically using the json4s library and not through the internal support that dispatch library has for json am yet to figure that one out. But avoid asking for help, clarification, or responding to other answers. As soon as you have a type class able to transform the scala type to json, it is pretty easy to generate any scala value to json.

However, note that it handles timeouts very poorly, such as if the web service youre calling is down or running slowly. Format of the data being exchanged example, plain text, json, csv. If you know scala and are familiar with json, there isnt much to say about this example. An example showing how this matters is the way that i created the music. Easy json unmarshalling in scala with jackson example. The way you normally do this is via a jsonprotocol. How to get content from a rest url get rest content.

It turns out that the situation is similar if not worse when it. Setting up scala on android the programming corner. How to create json strings from scala classes that have. In fact spray json even reuses some of sjson s code, see the credits section below. As your classes grow, creating a larger json generator in one variable becomes hard to read and maintain. Ive also read that the android environment in general doesnt play well at all with extraction to case classes.

Simple examples a list of simple scala snippets, useful to understand some basics of the language, as well as to see what scala code looks like. Json stands for javascript object notation and is use for data interchange between android application and a server. Files with nested json objects, one per line, with both string and numeric values so basically a mapstring, any. A quick tour of json libraries in scala manuel bernhardt. This action expects a request with a contenttype header of textjson or applicationjson and a body containing a json representation of the entity to create. This tutorial is sponsored by the scala cookbook, which i wrote for oreilly.