File size: 6,437 Bytes
9e42181 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | # Fetchers basics
## Introduction
Fetchers are classes that do requests or fetch pages in a single-line fashion with many features and return a [Response](#response-object) object. All fetchers have separate session classes to keep the session running (e.g., a browser fetcher keeps the browser open until you finish all requests).
Fetchers are not wrappers built on top of other libraries. They use these libraries as an engine to request/fetch pages but add features the underlying engines don't have, while still fully leveraging and optimizing them for web scraping.
## Fetchers Overview
Scrapling provides three different fetcher classes with their session classes; each fetcher is designed for a specific use case.
The following table compares them and can be quickly used for guidance.
| Feature | Fetcher | DynamicFetcher | StealthyFetcher |
|--------------------|---------------------------------------------------|-----------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|
| Relative speed | 🐇🐇🐇🐇🐇 | 🐇🐇🐇 | 🐇🐇🐇 |
| Stealth | ⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ |
| Anti-Bot options | ⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ |
| JavaScript loading | ❌ | ✅ | ✅ |
| Memory Usage | ⭐ | ⭐⭐⭐ | ⭐⭐⭐ |
| Best used for | Basic scraping when HTTP requests alone can do it | - Dynamically loaded websites <br/>- Small automation<br/>- Small-Mid protections | - Dynamically loaded websites <br/>- Small automation <br/>- Small-Complicated protections |
| Browser(s) | ❌ | Chromium and Google Chrome | Chromium and Google Chrome |
| Browser API used | ❌ | PlayWright | PlayWright |
| Setup Complexity | Simple | Simple | Simple |
## Parser configuration in all fetchers
All fetchers share the same import method, as you will see in the upcoming pages
```python
>>> from scrapling.fetchers import Fetcher, AsyncFetcher, StealthyFetcher, DynamicFetcher
```
Then you use it right away without initializing like this, and it will use the default parser settings:
```python
>>> page = StealthyFetcher.fetch('https://example.com')
```
If you want to configure the parser ([Selector class](parsing/main_classes.md#selector)) that will be used on the response before returning it for you, then do this first:
```python
>>> from scrapling.fetchers import Fetcher
>>> Fetcher.configure(adaptive=True, keep_comments=False, keep_cdata=False) # and the rest
```
or
```python
>>> from scrapling.fetchers import Fetcher
>>> Fetcher.adaptive=True
>>> Fetcher.keep_comments=False
>>> Fetcher.keep_cdata=False # and the rest
```
Then, continue your code as usual.
The available configuration arguments are: `adaptive`, `adaptive_domain`, `huge_tree`, `keep_comments`, `keep_cdata`, `storage`, and `storage_args`, which are the same ones you give to the [Selector](parsing/main_classes.md#selector) class. You can display the current configuration anytime by running `<fetcher_class>.display_config()`.
**Info:** The `adaptive` argument is disabled by default; you must enable it to use that feature.
### Set parser config per request
As you probably understand, the logic above for setting the parser config will apply globally to all requests/fetches made through that class, and it's intended for simplicity.
If your use case requires a different configuration for each request/fetch, you can pass a dictionary to the request method (`fetch`/`get`/`post`/...) to an argument named `selector_config`.
## Response Object
The `Response` object is the same as the [Selector](parsing/main_classes.md#selector) class, but it has additional details about the response, like response headers, status, cookies, etc., as shown below:
```python
>>> from scrapling.fetchers import Fetcher
>>> page = Fetcher.get('https://example.com')
>>> page.status # HTTP status code
>>> page.reason # Status message
>>> page.cookies # Response cookies as a dictionary
>>> page.headers # Response headers
>>> page.request_headers # Request headers
>>> page.history # Response history of redirections, if any
>>> page.body # Raw response body as bytes
>>> page.encoding # Response encoding
>>> page.meta # Response metadata dictionary (e.g., proxy used). Mainly helpful with the spiders system.
```
All fetchers return the `Response` object.
**Note:** Unlike the [Selector](parsing/main_classes.md#selector) class, the `Response` class's body is always bytes since v0.4. |