JSLT is a complete query and transformation language for JSON. The language design is inspired by jq, XPath, and XQuery.
JSLT can be used as:
.foo.bar[0]),starts-with(.foo.bar[0], "http://")) ,Here is an example transform:
{
"time": round(parse-time(.published, "yyyy-MM-dd'T'HH:mm:ssX") * 1000),
"device_manufacturer": .device.manufacturer,
"device_model": .device.model,
"language": .device.acceptLanguage,
"os_name": .device.osType,
"os_version": .device.osVersion,
"platform": .device.platformType,
"user_properties": {
"is_logged_in" : boolean(.actor."spt:userId")
}
}
| Operation | Explanation |
|---|---|
. |
The context node |
.<name> |
Get value of key "<name>" inside an object |
.[<index>] |
Get value <index> inside an array |
.[<from> : <to>] |
Array slicing |
if (<expr>) <expr> else <expr> |
If test to decide which value to return |
let <name> = <expr> |
Define a variable |
$<name> |
Refer to a variable |
[for (<expr>) <expr>] |
Transform an array |
{for (<expr>) <expr> : <expr>} |
Transform an object |
def <name>(<name>, <name>...) <expr> |
Declare a function |
// <anything up to end of line> |
Comment |
{ <key> : <expr> } |
Object constructor |
{ <key> : <expr>, * : . } |
Specify one key, copy rest of input |
5 * 7 + 23.2 |
Arithmetic operations |
7 < 5 |
Comparators |
7 < 5 and .foo == "yes" |
Boolean operators |
To include JSLT in your project, depend on:
<dependency>
<groupId>com.schibsted.spt.data</groupId>
<artifactId>jslt</artifactId>
<version>0.1.10</version>
</dependency>At runtime JSLT depends on Jackson, and nothing else.
To transform one JsonNode into another, do:
import com.schibsted.spt.data.jslt.Parser;
import com.schibsted.spt.data.jslt.Expression;
JsonNode input = ...;
Expression jslt = Parser.compileString(transform);
JsonNode output = jslt.apply(input);For more alternatives, see the javadoc.
To run transforms on the command-line, first build with ./gradlew clean shadowJar. Then you can run with:
java -cp build/libs/*.jar com.schibsted.spt.data.jslt.cli.JSLT transform.jslt input.jsonThe result is written to standard out.
You can implement your own functions and add them to the language. See the extension function tutorial.
If you have questions about how to use JSLT, please ask the question
on StackOverflow, with the tag jslt.
If you have problems, feature requests, or think you found a bug, please open an issue.
The language design is not finished, so features may be added. The language as it stands is not likely to change.
The entire language is implemented, and all of the function library. Functions may be added.
The language has been used in production at Schibsted since January 2018, performing about 9 billion transforms per day, and many times more queries.
Developing a language for JSON processing: video of talk, slides only.
Anthony Sparks is working on a VM-based implementation in Java
A paper describing (among other things) some of the ways Schibsted uses JSLT.
Visual Studio syntax highlighter for JSLT.
Pincette event sourcing framework uses JSLT.
Copyright (c) 2018 Schibsted Marketplaces Products & Technology AS
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.
Things to be done:
let and def.... and boolean( ... ) by removing boolean().See also the list of ideas.