JsonPath

JsonPath offers a query notation for JSON documents.The following example and reference are copied from the Github project this library is based on: https://github.com/json-path/JsonPath

Some JSON is coming from sources that serialize polymorphic class structures, which are not handled by the built-in jsonToClass() primitive. In these cases, there is no way to get the class presentations of these JSON data structures. However, often you can identify the parts of the structure that are unambiguous, and would like to feed these parts to jsonToClass().

The below class diagram shows all available functionality:

There is one polymorphic operation that allows evaluation of a JsonPath expression against a document. One version expects the document as a JSON String, the other as a reference to a previously cached document (see Json Document Cache).

JsonPath Examples

Json Path Reference

Example Usage

The library source model contains a usage example based on the JSON data structure in the left column. Notice that there are two different classes inheriting from Article, namely Bicycle and Book.

Using the built-in classToJson() creates the below result. Notice that while being able to parse it, the "articles" array elements are parsed on the abstract Article level only. (It should not be possible to instantiate abstract classes, but thank god it works this way).

JSON Source

Class Structure

jsonToClass() Result

Suppose we want to parse the JSON structure and are only interested in articles that are books. The JsonPath expression

$.store.articles[?(@.category)]

will return an Array of all elements in the JSON articles array that have an attribute 'category'. So we are lucky, there is a JsonPath expression that selectively retrieves all elements we want in one go. The below Activity diagram returns the Warehouse instance after post-processing it.

Activity

Result

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