ScrewXml: A Beginner’s Guide to Getting StartedScrewXml is a lightweight XML processing library designed to simplify reading, writing, and manipulating XML documents with a minimal learning curve. This guide walks you through the core concepts, installation, basic usage patterns, common tasks, and tips to help you become productive quickly.
What is ScrewXml?
ScrewXml is a compact XML library focused on simplicity and developer ergonomics. It exposes a straightforward API for parsing, querying, creating, and serializing XML without heavy dependencies or complex configuration. ScrewXml is particularly well suited for small- to medium-sized projects, tools, and scripts where ease of use and clarity are valued over heavyweight enterprise features.
Key concepts
- Document: The top-level XML container (root and optional prolog/DTD).
- Element: A node with a tag name, attributes, text content, and child nodes.
- Attribute: A key-value pair attached to an element.
- Text node: The textual content inside an element.
- Namespace: Optional URI-qualified names for elements/attributes to avoid naming collisions.
- XPath-like queries: ScrewXml provides a simple querying mechanism inspired by XPath for finding nodes quickly (note: not full XPath support).
Installation
Installation instructions vary by language and package manager. Common options:
- For JavaScript/Node: npm install screwxml
- For Python: pip install screwxml
- For Java: Add the ScrewXml JAR to your build (Maven/Gradle coordinates: com.screwxml:screwxml:1.0.0)
Check the package registry for the latest version before installing.
Basic usage examples
Below are concise examples that demonstrate typical tasks: parsing XML, reading values, creating documents, modifying content, and serializing.
JavaScript (Node)
const { parse, create } = require('screwxml'); // Parsing const xmlString = `<books><book id="1"><title>1984</title></book></books>`; const doc = parse(xmlString); const title = doc.find('/books/book/title').text(); // "1984" // Creating const newDoc = create('library'); newDoc.root().append('book').attr('id', '2').append('title').text('Brave New World'); console.log(newDoc.toString()); Python
from screwxml import parse, create xml = '<books><book id="1"><title>1984</title></book></books>' doc = parse(xml) title = doc.find('/books/book/title').text # "1984" new_doc = create('library') new_doc.root.append('book').attr(id='2').append('title').text('Brave New World') print(new_doc.to_string()) Java (basic)
import com.screwxml.ScrewXml; import com.screwxml.Document; String xml = "<books><book id="1"><title>1984</title></book></books>"; Document doc = ScrewXml.parse(xml); String title = doc.find("/books/book/title").text(); Document newDoc = ScrewXml.create("library"); newDoc.getRoot().append("book").attr("id", "2").append("title").text("Brave New World"); System.out.println(newDoc.toString()); Parsing and querying
- parse(string) / parseFile(path): Load XML into a Document object.
- find(path): Simple path-based lookup (slash-delimited). Returns first matching node.
- findAll(path): Returns all matching nodes as a list/collection.
- text(): Retrieve text content for a node.
- attr(name): Get attribute value.
- children(): Enumerate child nodes.
Example: get all book titles
const titles = doc.findAll('/books/book/title').map(n => n.text()); Creating and modifying documents
- create(rootName, [namespaces]): Build a new document with a root element.
- root(): Access the root element.
- append(tagName): Add child element and return it for chaining.
- attr(name, value): Set attribute on an element.
- text(value): Set or get text content.
- remove(): Remove node from its parent.
- replaceWith(node): Replace a node.
Example: move a node to another parent
book = doc.find('/books/book[@id="1"]') new_parent = doc.find('/library') book.remove() new_parent.append(book) Namespaces
ScrewXml supports namespaces but aims for simple defaults. You can declare namespaces on creation or set them on elements:
- create(‘root’, {‘x’: ‘http://example.com/ns’})
- elem.attr(‘xmlns:x’, ‘http://example.com/ns’)
- use prefixed tag names like ‘x:item’ when appending/querying
Note: Query paths must use the same prefixes declared in the document context.
Serialization and formatting
- toString() / to_string(): Serialize document back to XML.
- prettyPrint(levels): Human-readable indentation.
- compact(): Minify output by removing unnecessary whitespace.
Example: pretty printing
console.log(doc.toString({ pretty: true, indent: 2 })); Error handling
- parse errors throw descriptive exceptions with line/column info.
- Invalid queries return null or empty collections rather than crashing.
- Use try/catch (or language equivalents) to handle malformed input.
Common tasks & recipes
- Convert XML to JSON-like object:
- Traverse nodes, convert element names to keys, attributes prefixed (e.g., @id), and text content under a special key (e.g., #text).
- Merge two XML documents:
- Import nodes from one doc to another using importNode/clone or string round-trip when import isn’t supported.
- Validate basic structure:
- Check required elements/attributes with find() and simple conditional logic.
- Strip namespaces:
- Clone elements and re-create them without namespace prefixes.
Performance tips
- For large documents, use streaming parsing (SAX-like) if available to avoid loading whole document into memory.
- Use findAll sparingly; prefer targeted paths or incremental processing.
- When modifying many nodes, build changes in-memory and serialize once.
When not to use ScrewXml
- If you need full XPath 2.0/XQuery, advanced schema validation (XSD), or enterprise-grade XML databases, choose a heavier library/tool that specifically supports those features.
- For extremely large XML streams where memory is constrained, use a streaming parser designed for low memory.
Troubleshooting common issues
- Parsing error: check for malformed tags, unescaped characters (&, <), and mismatched encoding declarations.
- Missing nodes in queries: ensure path uses correct element names and any namespace prefixes match the document.
- Unexpected whitespace: use text().trim() or the library’s normalization/compact options.
Learning resources
- Official docs and API reference (search your package registry or project site).
- Small hands-on projects: build a config reader, an XML-to-CSV converter, or a sitemap generator.
- Compare examples in your language of choice to understand idiomatic usage.
Example project: simple sitemap generator (Node)
- Read a list of URLs from a JSON file.
- Create a ScrewXml document with root
. - For each URL, append
… … - Serialize with pretty print and write to sitemap.xml.
ScrewXml keeps XML tasks approachable by minimizing ceremony and focusing on common developer workflows. With the examples and patterns above you should be able to parse, modify, and generate XML for most everyday tasks quickly.
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