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From $OBJ

See also: Web/Data Scraping & Automation Best Practices

Best Practices: - Always check for $ERR when accessing attributes or elements that may not exist. - Use functional chaining (.map(), .reduce(), .filter()) for processing extraction results. - Prefer .findall() for complex queries and nested extraction patterns.

data = json(rawdata)

data = xml(rawxml)

data = html(rawhtml)

data = findall(term)

Searches for all occurances of a match against JSON, XML or HTML data.

Each item in search is optional.

The has, nhas, and, nand, or, nor are all recursive.

n in nhas, nand, and nor indicates negation. 

search = {
  name:"", 
  value:"", 
  attr:attrlist, 
  has:searchlist, 
  nhas:searchlist, 
  and:searchlist, 
  nand:searchlist, 
  or:searchlist, 
  nor:searchlist
  }
 attrlist = {attr, attr, etc}
 attr = name: value
 searchlist = [search, search, etc]

Advanced Usage: Extracting Data from HTML

/* Parse HTML and extract all <a> tags with an <img> child */
html = $file().get("page.html").str().html();
anchors_with_images = html.body.findall({name:"a", has:{name:"img"}});

/* Extract hrefs, filtering out any <a> without an href attribute */
hrefs = anchors_with_images.reduce(op(acc, a) {
    if (a.$LIST.href.type() != $ERR) {
        acc += a.$LIST.href;
    }
}, []);

Explanation: - findall({name:"a", has:{name:"img"}}) finds all <a> tags that contain an <img> child. - The .reduce() collects the href attributes, skipping any that are missing.

Query Syntax Recap

  • name: Tag name to match (e.g., "a", "div")
  • attr: Match attributes (e.g., {id:"main", class:"header"})
  • has: Require child/descendant elements matching a query
  • nhas: Require absence of child/descendant elements
  • and, or, nand, nor: Combine multiple queries (logical operations)

Best Practices

  • Chain .findall() calls to traverse nested structures.
  • Use functional methods (.map(), .reduce()) to process results.
  • Always check for $ERR when accessing properties that may not exist.

Note on JSON and XML

The same .findall() principles apply to complex JSON and XML documents. You can use the same query patterns to extract nested data, filter by attributes/keys, and process results with functional methods.

Note on .get() for $OBJ

There is no built-in .get() method for $OBJ in Grapa. If you want a .get() method, you must define it yourself as a member function in your class. Its behavior is entirely determined by your implementation.

Example: / You must define get() yourself if you want it / 

Person = class {
    name = "";
    age = 0;
    get = op() { {"name": name, "age": age}; };
};
p = obj Person;
p.get();

If you do not define a .get() method, calling p.get() will result in an error.

.get() is not like Python or JavaScript, where it is built-in for objects/dicts.

See Also: - Language Reference - Python-to-Grapa Migration Guide - JS-to-Grapa Migration Guide - Examples