TL;DR
Schema-based extraction is defining the output structure you want upfront (the fields, their types, and their relationships) and letting the extraction system map page content onto it. Instead of writing custom parsing per site, you declare the shape and receive consistent, typed, validated data across different sources.
How It Works
Schema extraction is a data extraction approach where you define the desired output structure (schema) upfront, and the extraction system maps source content to that structure. Rather than writing custom parsing logic for each data source, you specify what fields you want, their types, and their relationships, and the extraction engine handles the mapping.
How Schema Extraction Works
You define a schema that describes your desired output:
{
"name": "string",
"price": "number",
"currency": "string",
"availability": "boolean",
"reviews": [{
"author": "string",
"rating": "number",
"text": "string"
}]
}The extraction system then analyzes the source content and populates this schema with the relevant data. The output is guaranteed to conform to your defined structure, regardless of how the source page is laid out.
Benefits of Schema-Based Extraction
Consistency
Every extraction produces output in the same format. Whether you are scraping one site or a hundred, the resulting data has identical field names, types, and nesting. This eliminates the normalization step that plagues ad-hoc scraping.
Validation
The schema acts as a contract. Missing required fields, wrong types, or structural violations can be caught immediately rather than surfacing as bugs downstream in your data pipeline.
Reusability
The same schema works across different sources. A product schema designed for one e-commerce site works for others, and only the extraction mapping changes, not the output format.
Documentation
The schema itself documents what data your pipeline produces. New team members can understand the data structure by reading the schema without examining extraction code.
Schema Extraction in ScrapeGraphAI
Schema extraction is a core capability of ScrapeGraphAI. You provide a JSON schema or Pydantic model describing your desired output, and the extract endpoint maps page content to it, returning typed JSON validated against your schema.