@quadient/evolve-data-transformations

Data Transformations Package

Table of Contents

• XML
  • XML Example
• JSON
  • JSON Example

Overview

The Data Transformations package contains helper utilities to work with JSON, XML and CSV data formats.

XML

Async streaming XML Parser and Writer.

XmlParser receives strings with parts of the XML content in the "write" method and the callback given to parser constructor receives events of type XmlEvent.

XmlWriter is the opposite component. It receives XmlEvent objects in the write method and the callback given to constructor receives a string with the XML content.

There are also predefined TransformStream classes StringToXmlTransformStream and XmlToStringTransformStream for convenient use with streams.

XML Example

let writer = new XmlWriter(async (str) => {
    console.log(str);
});

let parser = new XmlParser(async (event) => {
    if (event.type === XmlEventType.START_TAG) {
        let elem = event.details as ElementDetails;
        if (elem.name == "name") {
            elem.name = "fixedName"
        }
    } else if (event.type === XmlEventType.END_TAG) {
        if (event.details === "name") {
            event.details = "fixedName"
        }
    }
    await writer.write(event);
});

await parser.parse(`<person><name>Fred</name></person>`);
await parser.flush(); // must be called at the end of parsing
await writer.flush(); // must be called at the end of writing

Output:

<person><fixedName>Fred</fixedName></person>

JSON

Async streaming JSON Parser and Writer.

JsonParser receives strings with parts of the JSON content in the write method and the callback given to parser constructor receives events of type JsonEvent.

JsonWriter is the opposite component. It receives JsonEvent objects in the write method and the callback given to constructor receives a string with the JSON content.

JSON Example

let writer = new JsonWriter(async (str) => {
    console.log(str);
});

let parser = new JsonParser(async (event) => {
    if(event.type === JsonEventType.PROPERTY_NAME && event.data === "name") {
        event.data = "fixedName";
    }
    await writer.write(event);
})

await parser.parse(`{"person": {"name":"Fred"}}`);
await parser.flush(); // must be called at the end of parsing
await writer.flush(); // must be caleld at the end of writing

Output:

{"person":{"fixedName":"Fred"}}