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Introduction
💡 Prerequisites:
- You’ve completed or read the Querying elements page to understand how to find/extract elements from the Selector object.
After exploring the various ways to select elements with Scrapling and its related features, let's take a step back and examine the Selector class in general, as well as other objects, to gain a better understanding of the parsing engine.
The Selector class is the core parsing engine in Scrapling, providing HTML parsing and element selection capabilities. You can always import it with any of the following imports
from scrapling import Selector
from scrapling.parser import Selector
Then use it directly as you already learned in the overview page
page = Selector(
'<html>...</html>',
url='https://example.com'
)
# Then select elements as you like
elements = page.css('.product')
In Scrapling, the main object you deal with after passing an HTML source or fetching a website is, of course, a Selector object. Any operation you do, like selection, navigation, etc., will return either a Selector object or a Selectors object, given that the result is element/elements from the page, not text or similar.
In other words, the main page is a Selector object, and the elements within are Selector objects, and so on. Any text, such as the text content inside elements or the text inside element attributes, is a TextHandler object, and the attributes of each element are stored as AttributesHandler. We will return to both objects later, so let's focus on the Selector object.
Selector
Arguments explained
The most important one is content, it's used to pass the HTML code you want to parse, and it accepts the HTML content as str or bytes.
Otherwise, you have the arguments url, adaptive, storage, and storage_args. All these arguments are settings used with the adaptive feature, and they don't make a difference if you are not going to use that feature, so just ignore them for now, and we will explain them in the adaptive feature page.
Then you have the arguments for parsing adjustments or adjusting/manipulating the HTML content while the library is parsing it:
- encoding: This is the encoding that will be used while parsing the HTML. The default is
UTF-8. - keep_comments: This tells the library whether to keep HTML comments while parsing the page. It's disabled by default because it can cause issues with your scraping in various ways.
- keep_cdata: Same logic as the HTML comments. cdata is removed by default for cleaner HTML.
I have intended to ignore the arguments huge_tree and root to avoid making this page more complicated than needed.
You may notice that I'm doing that a lot because it involves advanced features that you don't need to know to use the library. The development section will cover these missing parts if you are very invested.
After that, for the main page and elements within, most properties are lazily loaded. This means they don't get initialized until you use them like the text content of a page/element, and this is one of the reasons for Scrapling speed :)
Properties
You have already seen much of this on the overview page, but don't worry if you didn't. We will review it more thoroughly using more advanced methods/usages. For clarity, the properties for traversal are separated below in the traversal section.
Let's say we are parsing this HTML page for simplicity:
<html>
<head>
<title>Some page</title>
</head>
<body>
<div class="product-list">
<article class="product" data-id="1">
<h3>Product 1</h3>
<p class="description">This is product 1</p>
<span class="price">$10.99</span>
<div class="hidden stock">In stock: 5</div>
</article>
<article class="product" data-id="2">
<h3>Product 2</h3>
<p class="description">This is product 2</p>
<span class="price">$20.99</span>
<div class="hidden stock">In stock: 3</div>
</article>
<article class="product" data-id="3">
<h3>Product 3</h3>
<p class="description">This is product 3</p>
<span class="price">$15.99</span>
<div class="hidden stock">Out of stock</div>
</article>
</div>
<script id="page-data" type="application/json">
{
"lastUpdated": "2024-09-22T10:30:00Z",
"totalProducts": 3
}
</script>
</body>
</html>
Load the page directly as shown before:
from scrapling import Selector
page = Selector(html_doc)
Get all text content on the page recursively
>>> page.get_all_text()
'Some page\n\n \n\n \nProduct 1\nThis is product 1\n$10.99\nIn stock: 5\nProduct 2\nThis is product 2\n$20.99\nIn stock: 3\nProduct 3\nThis is product 3\n$15.99\nOut of stock'
Get the first article, as explained before; we will use it as an example
article = page.find('article')
With the same logic, get all text content on the element recursively
>>> article.get_all_text()
'Product 1\nThis is product 1\n$10.99\nIn stock: 5'
But if you try to get the direct text content, it will be empty because it doesn't have direct text in the HTML code above
>>> article.text
''
The get_all_text method has the following optional arguments:
- separator: All strings collected will be concatenated using this separator. The default is '\n'
- strip: If enabled, strings will be stripped before concatenation. Disabled by default.
- ignore_tags: A tuple of all tag names you want to ignore in the final results and ignore any elements nested within them. The default is
('script', 'style',). - valid_values: If enabled, the method will only collect elements with real values, so all elements with empty text content or only whitespaces will be ignored. It's enabled by default
By the way, the text returned here is not a standard string but a TextHandler; we will get to this in detail later, so if the text content can be serialized to JSON, use .json() on it
>>> script = page.find('script')
>>> script.json()
{'lastUpdated': '2024-09-22T10:30:00Z', 'totalProducts': 3}
Let's continue to get the element tag
>>> article.tag
'article'
If you use it on the page directly, you will find that you are operating on the root html element
>>> page.tag
'html'
Now, I think I hammered the (page/element) idea, so I won't return to it again.
Getting the attributes of the element
>>> print(article.attrib)
{'class': 'product', 'data-id': '1'}
Access a specific attribute with any of the following
>>> article.attrib['class']
>>> article.attrib.get('class')
>>> article['class'] # new in v0.3
Check if the attributes contain a specific attribute with any of the methods below
>>> 'class' in article.attrib
>>> 'class' in article # new in v0.3
Get the HTML content of the element
>>> article.html_content
'<article class="product" data-id="1"><h3>Product 1</h3>\n <p class="description">This is product 1</p>\n <span class="price">$10.99</span>\n <div class="hidden stock">In stock: 5</div>\n </article>'
Get the prettified version of the element's HTML content
print(article.prettify())
<article class="product" data-id="1"><h3>Product 1</h3>
<p class="description">This is product 1</p>
<span class="price">$10.99</span>
<div class="hidden stock">In stock: 5</div>
</article>
Use the .body property to get the raw content of the page
>>> page.body
'<html>\n <head>\n <title>Some page</title>\n </head>\n <body>\n <div class="product-list">\n <article class="product" data-id="1">\n <h3>Product 1</h3>\n <p class="description">This is product 1</p>\n <span class="price">$10.99</span>\n <div class="hidden stock">In stock: 5</div>\n </article>\n\n <article class="product" data-id="2">\n <h3>Product 2</h3>\n <p class="description">This is product 2</p>\n <span class="price">$20.99</span>\n <div class="hidden stock">In stock: 3</div>\n </article>\n\n <article class="product" data-id="3">\n <h3>Product 3</h3>\n <p class="description">This is product 3</p>\n <span class="price">$15.99</span>\n <div class="hidden stock">Out of stock</div>\n </article>\n </div>\n\n <script id="page-data" type="application/json">\n {\n "lastUpdated": "2024-09-22T10:30:00Z",\n "totalProducts": 3\n }\n </script>\n </body>\n</html>'
To get all the ancestors in the DOM tree of this element
>>> article.path
[<data='<div class="product-list"> <article clas...' parent='<body> <div class="product-list"> <artic...'>,
<data='<body> <div class="product-list"> <artic...' parent='<html><head><title>Some page</title></he...'>,
<data='<html><head><title>Some page</title></he...'>]
Generate a CSS shortened selector if possible, or generate the full selector
>>> article.generate_css_selector
'body > div > article'
>>> article.generate_full_css_selector
'body > div > article'
Same case with XPath
>>> article.generate_xpath_selector
"//body/div/article"
>>> article.generate_full_xpath_selector
"//body/div/article"
Traversal
Using the elements we found above, we will go over the properties/methods for moving on the page in detail.
If you are unfamiliar with the DOM tree or the tree data structure in general, the following traversal part can be confusing. I recommend you look up these concepts online for a better understanding.
If you are too lazy to search about it, here's a quick explanation to give you a good idea.
In simple words, the html element is the root of the website's tree, as every page starts with an html element.
This element will be positioned directly above elements such as head and body. These are considered "children" of the html element, and the html element is considered their "parent". The element body is a "sibling" of the element head and vice versa.
Accessing the parent of an element
>>> article.parent
<data='<div class="product-list"> <article clas...' parent='<body> <div class="product-list"> <artic...'>
>>> article.parent.tag
'div'
You can chain it as you want, which applies to all similar properties/methods we will review.
>>> article.parent.parent.tag
'body'
Get the children of an element
>>> article.children
[<data='<h3>Product 1</h3>' parent='<article class="product" data-id="1"><h3...'>,
<data='<p class="description">This is product 1...' parent='<article class="product" data-id="1"><h3...'>,
<data='<span class="price">$10.99</span>' parent='<article class="product" data-id="1"><h3...'>,
<data='<div class="hidden stock">In stock: 5</d...' parent='<article class="product" data-id="1"><h3...'>]
Get all elements underneath an element. It acts as a nested version of the children property
>>> article.below_elements
[<data='<h3>Product 1</h3>' parent='<article class="product" data-id="1"><h3...'>,
<data='<p class="description">This is product 1...' parent='<article class="product" data-id="1"><h3...'>,
<data='<span class="price">$10.99</span>' parent='<article class="product" data-id="1"><h3...'>,
<data='<div class="hidden stock">In stock: 5</d...' parent='<article class="product" data-id="1"><h3...'>]
This element returns the same result as the children property because its children don't have children.
Another example of using the element with the product-list class will clear the difference between the children property and the below_elements property
>>> products_list = page.css_first('.product-list')
>>> products_list.children
[<data='<article class="product" data-id="1"><h3...' parent='<div class="product-list"> <article clas...'>,
<data='<article class="product" data-id="2"><h3...' parent='<div class="product-list"> <article clas...'>,
<data='<article class="product" data-id="3"><h3...' parent='<div class="product-list"> <article clas...'>]
>>> products_list.below_elements
[<data='<article class="product" data-id="1"><h3...' parent='<div class="product-list"> <article clas...'>,
<data='<h3>Product 1</h3>' parent='<article class="product" data-id="1"><h3...'>,
<data='<p class="description">This is product 1...' parent='<article class="product" data-id="1"><h3...'>,
<data='<span class="price">$10.99</span>' parent='<article class="product" data-id="1"><h3...'>,
<data='<div class="hidden stock">In stock: 5</d...' parent='<article class="product" data-id="1"><h3...'>,
<data='<article class="product" data-id="2"><h3...' parent='<div class="product-list"> <article clas...'>,
...]
Get the siblings of an element
>>> article.siblings
[<data='<article class="product" data-id="2"><h3...' parent='<div class="product-list"> <article clas...'>,
<data='<article class="product" data-id="3"><h3...' parent='<div class="product-list"> <article clas...'>]
Get the next element of the current element
>>> article.next
<data='<article class="product" data-id="2"><h3...' parent='<div class="product-list"> <article clas...'>
The same logic applies to the previous property
>>> article.previous # It's the first child, so it doesn't have a previous element
>>> second_article = page.css_first('.product[data-id="2"]')
>>> second_article.previous
<data='<article class="product" data-id="1"><h3...' parent='<div class="product-list"> <article clas...'>
You can check easily and pretty fast if an element has a specific class name or not
>>> article.has_class('product')
True
If your case needs more than the element's parent, you can iterate over the whole ancestors' tree of any element, like the example below
for ancestor in article.iterancestors():
# do something with it...
You can search for a specific ancestor of an element that satisfies a search function; all you need to do is to pass a function that takes a Selector object as an argument and return True if the condition satisfies or False otherwise, like below:
>>> article.find_ancestor(lambda ancestor: ancestor.has_class('product-list'))
<data='<div class="product-list"> <article clas...' parent='<body> <div class="product-list"> <artic...'>
>>> article.find_ancestor(lambda ancestor: ancestor.css('.product-list')) # Same result, different approach
<data='<div class="product-list"> <article clas...' parent='<body> <div class="product-list"> <artic...'>
Selectors
The class Selectors is the "List" version of the Selector class. It inherits from the Python standard List type, so it shares all List properties and methods while adding more methods to make the operations you want to execute on the Selector instances within more straightforward.
In the Selector class, all methods/properties that should return a group of elements return them as a Selectors class instance. The only exceptions are when you use the CSS/XPath methods as follows:
- If you selected a text node with the selector, then the return type will be TextHandler/TextHandlers.
Examples:>>> page.css('a::text') # -> TextHandlers >>> page.xpath('//a/text()') # -> TextHandlers >>> page.css_first('a::text') # -> TextHandler >>> page.xpath_first('//a/text()') # -> TextHandler >>> page.css('a::attr(href)') # -> TextHandlers >>> page.xpath('//a/@href') # -> TextHandlers >>> page.css_first('a::attr(href)') # -> TextHandler >>> page.xpath_first('//a/@href') # -> TextHandler - If you used a combined selector that returns mixed types, the result will be a Python standard
List.
Examples:>>> page.css('.price_color') # -> Selectors >>> page.css('.product_pod a::attr(href)') # -> TextHandlers >>> page.css('.price_color, .product_pod a::attr(href)') # -> List
Let's see what Selectors class adds to the table with that out of the way.
Properties
Apart from the normal operations on Python lists, such as iteration and slicing, etc.
You can do the following:
Execute CSS and XPath selectors directly on the Selector instances it has, while the arguments and the return types are the same as Selector's css and xpath methods. This, of course, makes chaining methods very straightforward.
>>> page.css('.product_pod a')
[<data='<a href="catalogue/a-light-in-the-attic_...' parent='<div class="image_container"> <a href="c...'>,
<data='<a href="catalogue/a-light-in-the-attic_...' parent='<h3><a href="catalogue/a-light-in-the-at...'>,
<data='<a href="catalogue/tipping-the-velvet_99...' parent='<div class="image_container"> <a href="c...'>,
<data='<a href="catalogue/tipping-the-velvet_99...' parent='<h3><a href="catalogue/tipping-the-velve...'>,
<data='<a href="catalogue/soumission_998/index....' parent='<div class="image_container"> <a href="c...'>,
<data='<a href="catalogue/soumission_998/index....' parent='<h3><a href="catalogue/soumission_998/in...'>,
...]
>>> page.css('.product_pod').css('a') # Returns the same result
[<data='<a href="catalogue/a-light-in-the-attic_...' parent='<div class="image_container"> <a href="c...'>,
<data='<a href="catalogue/a-light-in-the-attic_...' parent='<h3><a href="catalogue/a-light-in-the-at...'>,
<data='<a href="catalogue/tipping-the-velvet_99...' parent='<div class="image_container"> <a href="c...'>,
<data='<a href="catalogue/tipping-the-velvet_99...' parent='<h3><a href="catalogue/tipping-the-velve...'>,
<data='<a href="catalogue/soumission_998/index....' parent='<div class="image_container"> <a href="c...'>,
<data='<a href="catalogue/soumission_998/index....' parent='<h3><a href="catalogue/soumission_998/in...'>,
...]
Run the re and re_first methods directly. They take the same arguments passed to the Selector class. I will still leave these methods to be explained in the TextHandler section below.
However, in this class, the re_first behaves differently as it runs re on each Selector within and returns the first one with a result. The re method will return a TextHandlers object as normal, which combines all the TextHandler instances into one TextHandlers instance.
>>> page.css('.price_color').re(r'[\d\.]+')
['51.77',
'53.74',
'50.10',
'47.82',
'54.23',
...]
>>> page.css('.product_pod h3 a::attr(href)').re(r'catalogue/(.*)/index.html')
['a-light-in-the-attic_1000',
'tipping-the-velvet_999',
'soumission_998',
'sharp-objects_997',
...]
With the search method, you can search quickly in the available Selector instances. The function you pass must accept a Selector instance as the first argument and return True/False. The method will return the first Selector instance that satisfies the function; otherwise, it will return None.
# Find all the products with price '53.23'
>>> search_function = lambda p: float(p.css('.price_color').re_first(r'[\d\.]+')) == 54.23
>>> page.css('.product_pod').search(search_function)
<data='<article class="product_pod"><div class=...' parent='<li class="col-xs-6 col-sm-4 col-md-3 co...'>
You can use the filter method, too, which takes a function like the search method but returns an Selectors instance of all the Selector instances that satisfy the function
# Find all products with prices over $50
>>> filtering_function = lambda p: float(p.css('.price_color').re_first(r'[\d\.]+')) > 50
>>> page.css('.product_pod').filter(filtering_function)
[<data='<article class="product_pod"><div class=...' parent='<li class="col-xs-6 col-sm-4 col-md-3 co...'>,
<data='<article class="product_pod"><div class=...' parent='<li class="col-xs-6 col-sm-4 col-md-3 co...'>,
<data='<article class="product_pod"><div class=...' parent='<li class="col-xs-6 col-sm-4 col-md-3 co...'>,
...]
If you are too lazy like me and want to know the number of Selector instances in a Selectors instance. You can do this:
page.css('.product_pod').length
instead of this
len(page.css('.product_pod'))
Yup, like JavaScript :)
TextHandler
This class is mandatory to understand, as all methods/properties that should return a string for you will return TextHandler, and the ones that should return a list of strings will return TextHandlers instead.
TextHandler is a subclass of the standard Python string, so you can do anything with it that you can do with a Python string. So, what is the difference that requires a different naming?
Of course, TextHandler provides extra methods and properties that standard Python strings can't do. We will review them now, but remember that all methods and properties in all classes that return string(s) return TextHandler, which opens the door for creativity and makes the code shorter and cleaner, as you will see. Also, you can import it directly and use it on any string, which we will explain later.
Usage
First, before discussing the added methods, you need to know that all operations on it, like slicing, accessing by index, etc., and methods like split, replace, strip, etc., all return a TextHandler again, so you can chain them as you want. If you find a method or property that returns a standard string instead of TextHandler, please open an issue, and we will override it as well.
First, we start with the re and re_first methods. These are the same methods that exist in the other classes (Selector, Selectors, and TextHandlers), so they will accept the same arguments as well.
-
The
remethod takes a string/compiled regex pattern as the first argument. It searches the data for all strings matching the regex and returns them as a TextHandlers instance. There_firstmethod takes the same arguments and behaves similarly, but as you probably figured out from the naming, it returns the first result only as aTextHandlerinstance.Also, it takes other helpful arguments, which are:
- replace_entities: This is enabled by default. It replaces character entity references with their corresponding characters.
- clean_match: It's disabled by default. This causes the method to ignore all whitespace and consecutive spaces while matching.
- case_sensitive: It's enabled by default. As the name implies, disabling it will cause the regex to ignore the case of letters while compiling.
You have seen these examples before; the return result is TextHandlers because we used the
remethod.>>> page.css('.price_color').re(r'[\d\.]+') ['51.77', '53.74', '50.10', '47.82', '54.23', ...] >>> page.css('.product_pod h3 a::attr(href)').re(r'catalogue/(.*)/index.html') ['a-light-in-the-attic_1000', 'tipping-the-velvet_999', 'soumission_998', 'sharp-objects_997', ...]To explain the other arguments better, we will use a custom string for each example below
>>> from scrapling import TextHandler >>> test_string = TextHandler('hi there') # Hence the two spaces >>> test_string.re('hi there') >>> test_string.re('hi there', clean_match=True) # Using `clean_match` will clean the string before matching the regex ['hi there'] >>> test_string2 = TextHandler('Oh, Hi Mark') >>> test_string2.re_first('oh, hi Mark') >>> test_string2.re_first('oh, hi Mark', case_sensitive=False) # Hence disabling `case_sensitive` 'Oh, Hi Mark' # Mixing arguments >>> test_string.re('hi there', clean_match=True, case_sensitive=False) ['hi There']Another use of the idea of replacing strings with
TextHandlereverywhere is that a property likehtml_contentreturnsTextHandler, so you can do regex on the HTML content if you want:>>> page.html_content.re('div class=".*">(.*)</div') ['In stock: 5', 'In stock: 3', 'Out of stock'] -
You also have the
.json()method, which tries to convert the content to a JSON object quickly if possible; otherwise, it throws an error>>> page.css_first('#page-data::text') '\n {\n "lastUpdated": "2024-09-22T10:30:00Z",\n "totalProducts": 3\n }\n ' >>> page.css_first('#page-data::text').json() {'lastUpdated': '2024-09-22T10:30:00Z', 'totalProducts': 3}Hence, if you didn't specify a text node while selecting an element (like the text content or an attribute text content), the text content will be selected automatically, like this
>>> page.css_first('#page-data').json() {'lastUpdated': '2024-09-22T10:30:00Z', 'totalProducts': 3}The Selector class adds one thing here, too; let's say this is the page we are working with:
<html> <body> <div> <script id="page-data" type="application/json"> { "lastUpdated": "2024-09-22T10:30:00Z", "totalProducts": 3 } </script> </div> </body> </html>The Selector class has the
get_all_textmethod, which you should be aware of by now. This method returns aTextHandler, of course.
So, as you know here, if you did something like this>>> page.css_first('div::text').json()You will get an error because the
divtag doesn't have direct text content that can be serialized to JSON; it actually doesn't have direct text content at all.
In this case, theget_all_textmethod comes to the rescue, so you can do something like that>>> page.css_first('div').get_all_text(ignore_tags=[]).json() {'lastUpdated': '2024-09-22T10:30:00Z', 'totalProducts': 3}I used the
ignore_tagsargument here because the default value of it is('script', 'style',), as you are aware.
Another related behavior to be aware of occurs when using any of the fetchers, which we will explain later. If you have a JSON response like this example:>>> page = Selector("""{"some_key": "some_value"}""")Because the Selector class is optimized to deal with HTML pages, it will deal with it as a broken HTML response and fix it, so if you used the
html_contentproperty, you get this>>> page.html_content '<html><body><p>{"some_key": "some_value"}</p></body></html>'Here, you can use the
jsonmethod directly, and it will work>>> page.json() {'some_key': 'some_value'}You might wonder how this happened, given that the
htmltag doesn't contain direct text.
Well, for cases like JSON responses, I made the Selector class maintain a raw copy of the content passed to it. This way, when you use the.json()method, it checks for that raw copy and then converts it to JSON. If the raw copy is not available like the case with the elements, it checks for the current element text content, or otherwise it used theget_all_textmethod directly.
This might sound hacky a bit but remember, Scrapling is currently optimized to work with HTML pages only so that's the best way till now to handle JSON responses currently without sacrificing speed. This will be changed in the upcoming versions. -
Another handy method is
.clean(), which will remove all white spaces and consecutive spaces for you and return a newTextHandlerinstance
>>> TextHandler('\n wonderful idea, \reh?').clean()
'wonderful idea, eh?'
- Another method that might be helpful in some cases is the
.sort()method to sort the string for you, as you do with lists
>>> TextHandler('acb').sort()
'abc'
Or do it in reverse:
>>> TextHandler('acb').sort(reverse=True)
'cba'
Other methods and properties will be added over time, but remember that this class is returned in place of strings nearly everywhere in the library.
TextHandlers
You probably guessed it: This class is similar to Selectors and Selector, but here it inherits the same logic and method as standard lists, with only re and re_first as new methods.
The only difference is that the re_first method logic here does re on each TextHandler within and returns the first result it has or None. Nothing new needs to be explained here, but new methods will be added over time.
AttributesHandler
This is a read-only version of Python's standard dictionary, or dict, that is used solely to store the attributes of each element or each Selector instance.
>>> print(page.find('script').attrib)
{'id': 'page-data', 'type': 'application/json'}
>>> type(page.find('script').attrib).__name__
'AttributesHandler'
Because it's read-only, it will use fewer resources than the standard dictionary. Still, it has the same dictionary method and properties, except those that allow you to modify/override the data.
It currently adds two extra simple methods:
-
The
search_valuesmethodIn standard dictionaries, you can do
dict.get("key_name")to check if a key exists. However, if you want to search by values instead of keys, it will require some additional code lines. This method does that for you. It allows you to search the current attributes by values and returns a dictionary of each matching item.A simple example would be
>>> for i in page.find('script').attrib.search_values('page-data'): print(i) {'id': 'page-data'}But this method provides the
partialargument as well, which allows you to search by part of the value:>>> for i in page.find('script').attrib.search_values('page', partial=True): print(i) {'id': 'page-data'}These examples won't happen in the real world; most likely, a more real-world example would be using it with the
find_allmethod to find all elements that have a specific value in their arguments:>>> page.find_all(lambda element: list(element.attrib.search_values('product'))) [<data='<article class="product" data-id="1"><h3...' parent='<div class="product-list"> <article clas...'>, <data='<article class="product" data-id="2"><h3...' parent='<div class="product-list"> <article clas...'>, <data='<article class="product" data-id="3"><h3...' parent='<div class="product-list"> <article clas...'>]All these elements have 'product' as a value for the attribute
class.Hence, I used the
listfunction here becausesearch_valuesreturns a generator, so it would beTruefor all elements. -
The
json_stringpropertyThis property converts current attributes to a JSON string if the attributes are JSON serializable; otherwise, it throws an error
>>>page.find('script').attrib.json_string b'{"id":"page-data","type":"application/json"}'