Meeseeks v0.10.0 Meeseeks

Meeseeks is an Elixir library for parsing and extracting data from HTML and XML with CSS or XPath selectors.

import Meeseeks.CSS

html = HTTPoison.get!("https://news.ycombinator.com/").body

for story <- Meeseeks.all(html, css("tr.athing")) do
  title = Meeseeks.one(story, css(".title a"))
  %{title: Meeseeks.text(title),
    url: Meeseeks.attr(title, "href")}
end
#=> [%{title: "...", url: "..."}, %{title: "...", url: "..."}, ...]

Dependencies

Meeseeks depends on html5ever via meeseeks_html5ever.

Because html5ever is a Rust library, you will need to have the Rust compiler installed.

This dependency is necessary because there are no HTML5 spec compliant parsers written in Elixir/Erlang.

Getting Started

Parse

Start by parsing a source (HTML/XML string or Meeseeks.TupleTree) into a Meeseeks.Document so that it can be queried.

Meeseeks.parse/1 parses the source as HTML, but Meeseeks.parse/2 accepts a second argument of either :html or :xml that specifies how the source is parsed.

document = Meeseeks.parse("<div id=main><p>1</p><p>2</p><p>3</p></div>")
#=> Meeseeks.Document<{...}>

The selection functions accept an unparsed source, parsing it as HTML, but parsing is expensive so parse ahead of time when running multiple selections on the same document.

Select

Next, use one of Meeseeks's selection functions - fetch_all, all, fetch_one, or one - to search for nodes.

All these functions accept a queryable (a source, a document, or a Meeseeks.Result), one or more Meeseeks.Selectors, and optionally an initial context.

all returns a (possibly empty) list of results representing every node matching one of the provided selectors, while one returns a result representing the first node to match a selector (depth-first) or nil if there is no match.

fetch_all and fetch_one work like all and one respectively, but wrap the result in {:ok, ...} if there is a match or return {:error, %Meeseeks.Error{type: :select, reason: :no_match}} if there is not.

To generate selectors, use the css macro provided by Meeseeks.CSS or the xpath macro provided by Meeseeks.XPath.

import Meeseeks.CSS
result = Meeseeks.one(document, css("#main p"))
#=> #Meeseeks.Result<{ <p>1</p> }>

import Meeseeks.XPath
result = Meeseeks.one(document, xpath("//*[@id='main']//p"))
#=> #Meeseeks.Result<{ <p>1</p> }>

Extract

Retrieve information from the Meeseeks.Result with an extraction function.

The extraction functions are attr, attrs, data, dataset, html, own_text, tag, text, tree.

Meeseeks.tag(result)
#=> "p"
Meeseeks.text(result)
#=> "1"
Meeseeks.tree(result)
#=> {"p", [], ["1"]}

The extraction functions html and tree work on Meeseeks.Documents in addition to Meeseeks.Results.

Meeseeks.html(document)
#=> "<html><head></head><body><div id=\"main\"><p>1</p><p>2</p><p>3</p></div></body></html>"

Custom Selectors

Meeseeks is designed to have extremely extensible selectors, and creating a custom selector is as easy as defining a struct that implements the Meeseeks.Selector behaviour.

defmodule CommentContainsSelector do
  use Meeseeks.Selector

  alias Meeseeks.Document

  defstruct value: ""

  def match(selector, %Document.Comment{} = node, _document, _context) do
    String.contains?(node.content, selector.value)
  end

  def match(_selector, _node, _document, _context) do
    false
  end
end

selector = %CommentContainsSelector{value: "TODO"}

Meeseeks.one("<!-- TODO: Close vuln! -->", selector)
#=> #Meeseeks.Result<{ <!-- TODO: Close vuln! --> }>

To learn more, check the documentation for Meeseeks.Selector and Meeseeks.Selector.Combinator

Summary

Types

extractable()

queryable()

selectors()

Functions

all(queryable, selectors)

Returns [Result, ...] if one or more nodes in the queryable match a selector, or [] if none do

all(queryable, selectors, context)

attr(extractable, attribute)

Returns the value of an attribute in a result, or nil if there isn't one

attrs(extractable)

Returns a result's attributes list, which may be empty, or nil if the result represents a node without attributes

data(extractable)

Returns the combined data of a result or the result's children, which may be an empty string

dataset(extractable)

Returns a map of a result's data attributes, or nil if the result represents a node without attributes

fetch_all(queryable, selectors)

Returns {:ok, [Result, ...]} if one of more nodes in the queryable match a selector, or {:error, %Meeseeks.Error{type: :select, reason: :no_match}} if none do

fetch_all(queryable, selectors, context)

fetch_one(queryable, selectors)

Returns {:ok, Result} for the first node in the queryable (depth-first) matching a selector, or {:error, %Meeseeks.Error{type: :select, reason: :no_match}} if none do

fetch_one(queryable, selectors, context)

html(extractable)

Returns a string representing the combined HTML of a document or result and its descendants

one(queryable, selectors)

Returns a Result for the first node in the queryable (depth-first) matching a selector, or nil if none do

one(queryable, selectors, context)

own_text(extractable)

Returns the combined text of a result or the result's children, which may be an empty string

parse(source)

Parses a string or Meeseeks.TupleTree into a Meeseeks.Document

parse(source, parser)

select(queryable, selectors, context)

Returns the accumulated result of walking the queryable, accumulating nodes that match a selector. Prefer all or one- select should only be used when a custom accumulator is required

tag(extractable)

Returns a result's tag, or nil if the result represents a node without a tag

text(extractable)

Returns the combined text of a result or the result's descendants, which may be an empty string

tree(extractable)

Returns the Meeseeks.TupleTree of a document or result and its descendants

Types

extractable()

extractable() :: Meeseeks.Document.t | Meeseeks.Result.t | nil

queryable()

queryable ::
  Meeseeks.Parser.source |
  Meeseeks.Document.t |
  Meeseeks.Result.t

selectors()

selectors() :: Meeseeks.Selector.t | [Meeseeks.Selector.t]

Functions

all(queryable, selectors)

all(queryable, selectors) ::
  [Meeseeks.Result.t] |
  {:error, Meeseeks.Error.t}

Returns [Result, ...] if one or more nodes in the queryable match a selector, or [] if none do.

Optionally accepts a Meeseeks.Context map.

Parses the source if it is not a Meeseeks.Document or Meeseeks.Result, and may return {:error, %Meeseeks.Error{type: parser} if there is a parse error.

If multiple selections are being ran on the same unparsed source, parse first to avoid unnecessary computation.

Examples

iex> import Meeseeks.CSS
iex> Meeseeks.all("<div id=main><p>1</p><p>2</p><p>3</p></div>", css("#main p")) |> List.first()
#Meeseeks.Result<{ <p>1</p> }>

all(queryable, selectors, context)

all(queryable, selectors, Meeseeks.Context.t) ::
  [Meeseeks.Result.t] |
  {:error, Meeseeks.Error.t}

attr(extractable, attribute)

attr(extractable, String.t) :: String.t | nil

Returns the value of an attribute in a result, or nil if there isn't one.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result = Meeseeks.one("<div id=example>Hi</div>", css("#example"))
#Meeseeks.Result<{ <div id="example">Hi</div> }>
iex> Meeseeks.attr(result, "id")
"example"

attrs(extractable)

attrs(extractable) :: [{String.t, String.t}] | nil

Returns a result's attributes list, which may be empty, or nil if the result represents a node without attributes.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result = Meeseeks.one("<div id=example>Hi</div>", css("#example"))
#Meeseeks.Result<{ <div id="example">Hi</div> }>
iex> Meeseeks.attrs(result)
[{"id", "example"}]

data(extractable)

data(extractable) :: String.t | nil

Returns the combined data of a result or the result's children, which may be an empty string.

Data is the content of <script> or <style> tags, or the content of comments starting with "[CDATA[" and ending with "]]". The latter behavior is to support the extraction of CDATA from HTML, since HTML5 parsers parse CDATA as comments.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result1 = Meeseeks.one("<div id=example>Hi</div>", css("#example"))
#Meeseeks.Result<{ <div id="example">Hi</div> }>
iex> Meeseeks.data(result1)
""
iex> result2 = Meeseeks.one("<script id=example>Hi</script>", css("#example"))
#Meeseeks.Result<{ <script id="example">Hi</script> }>
iex> Meeseeks.data(result2)
"Hi"

dataset(extractable)

dataset(extractable) :: %{optional(String.t) => String.t} | nil

Returns a map of a result's data attributes, or nil if the result represents a node without attributes.

Behaves like HTMLElement.dataset; only valid data attributes are included, and attribute names have "data-" removed and are converted to camelCase.

See: https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/dataset

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result = Meeseeks.one("<div id=example data-x-val=1 data-y-val=2></div>", css("#example"))
#Meeseeks.Result<{ <div id="example" data-x-val="1" data-y-val="2"></div> }>
iex> Meeseeks.dataset(result)
%{"xVal" => "1", "yVal" => "2"}

fetch_all(queryable, selectors)

fetch_all(queryable, selectors) ::
  {:ok, [Meeseeks.Result.t]} |
  {:error, Meeseeks.Error.t}

Returns {:ok, [Result, ...]} if one of more nodes in the queryable match a selector, or {:error, %Meeseeks.Error{type: :select, reason: :no_match}} if none do.

Optionally accepts a Meeseeks.Context map.

Parses the source if it is not a Meeseeks.Document or Meeseeks.Result, and may return {:error, %Meeseeks.Error{type: parser} if there is a parse error.

If multiple selections are being ran on the same unparsed source, parse first to avoid unnecessary computation.

Examples

iex> import Meeseeks.CSS
iex> Meeseeks.fetch_all("<div id=main><p>1</p><p>2</p><p>3</p></div>", css("#main p")) |> elem(1) |> List.first()
#Meeseeks.Result<{ <p>1</p> }>

fetch_all(queryable, selectors, context)

fetch_all(queryable, selectors, Meeseeks.Context.t) ::
  {:ok, [Meeseeks.Result.t]} |
  {:error, Meeseeks.Error.t}

fetch_one(queryable, selectors)

fetch_one(queryable, selectors) ::
  {:ok, Meeseeks.Result.t} |
  {:error, Meeseeks.Error.t}

Returns {:ok, Result} for the first node in the queryable (depth-first) matching a selector, or {:error, %Meeseeks.Error{type: :select, reason: :no_match}} if none do.

Optionally accepts a Meeseeks.Context map.

Parses the source if it is not a Meeseeks.Document or Meeseeks.Result, and may return {:error, %Meeseeks.Error{type: parser} if there is a parse error.

If multiple selections are being ran on the same unparsed source, parse first to avoid unnecessary computation.

Examples

iex> import Meeseeks.CSS
iex> Meeseeks.fetch_one("<div id=main><p>1</p><p>2</p><p>3</p></div>", css("#main p")) |> elem(1)
#Meeseeks.Result<{ <p>1</p> }>

fetch_one(queryable, selectors, context)

fetch_one(queryable, selectors, Meeseeks.Context.t) ::
  {:ok, Meeseeks.Result.t} |
  {:error, Meeseeks.Error.t}

html(extractable)

html(extractable) :: String.t | nil

Returns a string representing the combined HTML of a document or result and its descendants.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> document = Meeseeks.parse("<div id=example>Hi</div>")
iex> Meeseeks.html(document)
"<html><head></head><body><div id=\"example\">Hi</div></body></html>"
iex> result = Meeseeks.one(document, css("#example"))
#Meeseeks.Result<{ <div id="example">Hi</div> }>
iex> Meeseeks.html(result)
"<div id=\"example\">Hi</div>"

one(queryable, selectors)

one(queryable, selectors) ::
  Meeseeks.Result.t |
  nil |
  {:error, Meeseeks.Error.t}

Returns a Result for the first node in the queryable (depth-first) matching a selector, or nil if none do.

Optionally accepts a Meeseeks.Context map.

Parses the source if it is not a Meeseeks.Document or Meeseeks.Result, and may return {:error, %Meeseeks.Error{type: parser} if there is a parse error.

If multiple selections are being ran on the same unparsed source, parse first to avoid unnecessary computation.

Examples

iex> import Meeseeks.CSS
iex> Meeseeks.one("<div id=main><p>1</p><p>2</p><p>3</p></div>", css("#main p"))
#Meeseeks.Result<{ <p>1</p> }>

one(queryable, selectors, context)

one(queryable, selectors, Meeseeks.Context.t) ::
  Meeseeks.Result.t |
  nil |
  {:error, Meeseeks.Error.t}

own_text(extractable)

own_text(extractable) :: String.t | nil

Returns the combined text of a result or the result's children, which may be an empty string.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result = Meeseeks.one("<div>Hello, <b>World!</b></div>", css("div"))
#Meeseeks.Result<{ <div>Hello, <b>World!</b></div> }>
iex> Meeseeks.own_text(result)
"Hello,"

parse(source)

parse(Meeseeks.Parser.source) ::
  Meeseeks.Document.t |
  {:error, Meeseeks.Error.t}

Parses a string or Meeseeks.TupleTree into a Meeseeks.Document.

parse/1 parses as HTML, while parse/2 accepts a second argument of either :html or :xml that specifies how the source is parsed.

Examples

iex> Meeseeks.parse("<div id=main><p>Hello, Meeseeks!</p></div>")
#Meeseeks.Document<{...}>

iex> Meeseeks.parse({"div", [{"id", "main"}], [{"p", [], ["Hello, Meeseeks!"]}]})
#Meeseeks.Document<{...}>

iex> Meeseeks.parse("<book><author>GGK</author></book>", :xml)
#Meeseeks.Document<{...}>

parse(source, parser)

parse(Meeseeks.Parser.source, Meeseeks.Parser.type) ::
  Meeseeks.Document.t |
  {:error, Meeseeks.Error.t}

select(queryable, selectors, context)

select(queryable, selectors, Meeseeks.Context.t) ::
  any |
  {:error, Meeseeks.Error.t}

Returns the accumulated result of walking the queryable, accumulating nodes that match a selector. Prefer all or one- select should only be used when a custom accumulator is required.

Requires that a Meeseeks.Accumulator has been added to the context via Meeseeks.Context.add_accumulator/2, and will raise an error if it hasn't.

Parses the source if it is not a Meeseeks.Document or Meeseeks.Result, and may return {:error, %Meeseeks.Error{type: parser} if there is a parse error.

If multiple selections are being ran on the same unparsed source, parse first to avoid unnecessary computation.

Examples

iex> import Meeseeks.CSS
iex> accumulator = %Meeseeks.Accumulator.One{}
iex> context = Meeseeks.Context.add_accumulator(%{}, accumulator)
iex> Meeseeks.select("<div id=main><p>1</p><p>2</p><p>3</p></div>", css("#main p"), context)
#Meeseeks.Result<{ <p>1</p> }>

tag(extractable)

tag(extractable) :: String.t | nil

Returns a result's tag, or nil if the result represents a node without a tag.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result = Meeseeks.one("<div id=example>Hi</div>", css("#example"))
#Meeseeks.Result<{ <div id="example">Hi</div> }>
iex> Meeseeks.tag(result)
"div"

text(extractable)

text(extractable) :: String.t | nil

Returns the combined text of a result or the result's descendants, which may be an empty string.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> result = Meeseeks.one("<div>Hello, <b>World!</b></div>", css("div"))
#Meeseeks.Result<{ <div>Hello, <b>World!</b></div> }>
iex> Meeseeks.text(result)
"Hello, World!"

tree(extractable)

tree(extractable) :: Meeseeks.TupleTree.t | nil

Returns the Meeseeks.TupleTree of a document or result and its descendants.

Nil input returns nil.

Examples

iex> import Meeseeks.CSS
iex> document = Meeseeks.parse("<div id=example>Hi</div>")
iex> Meeseeks.tree(document)
[{"html", [],
  [{"head", [], []},
   {"body", [], [{"div", [{"id", "example"}], ["Hi"]}]}]}]
iex> result = Meeseeks.one(document, css("#example"))
#Meeseeks.Result<{ <div id="example">Hi</div> }>
iex> Meeseeks.tree(result)
{"div", [{"id", "example"}], ["Hi"]}