hurl/docs/capturing-response.md
2022-10-31 11:50:22 +01:00

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# Capturing Response
## Captures
Captures are optional values captured from the HTTP response, in a named variable. Captures can be the
response status code, part of or the entire the body, and response headers.
Captured variables are available through a run session; each new value of a given variable overrides the last value.
Captures allow using data from one request in another request, when working with
[CSRF tokens] for instance. Variables can also be initialized at the start of the
session, by passing [variable values], or can be used in [templates].
```hurl
# An example to show how to pass a CSRF token from one request
# to another:
# First GET request to get CSRF token value:
GET https://example.org
HTTP/1.1 200
# Capture the CSRF token value from html body.
[Captures]
csrf_token: xpath "normalize-space(//meta[@name='_csrf_token']/@content)"
# Do the login !
POST https://acmecorp.net/login?user=toto&password=1234
X-CSRF-TOKEN: {{csrf_token}}
HTTP/1.1 302
```
Structure of a capture:
<div class="schema-container schema-container u-font-size-2 u-font-size-3-sm">
<div class="schema">
<span class="schema-token schema-color-1">my_var<span class="schema-label">variable</span></span>
<span> : </span>
<span class="schema-token schema-color-2">xpath "string(//h1)"<span class="schema-label">query</span></span>
</div>
</div>
A capture consists of a variable name, followed by `:` and a query. The captures
section starts with `[Captures]`.
### Query
Query can be of the following type:
- [`status`](#status-capture)
- [`header`](#header-capture)
- [`url`](#url-capture)
- [`cookie`](#cookie-capture)
- [`body`](#body-capture)
- [`bytes`](#bytes-capture)
- [`xpath`](#xpath-capture)
- [`jsonpath`](#jsonpath-capture)
- [`regex`](#regex-capture)
- [`variable`](#variable-capture)
- [`duration`](#duration-capture)
### Status capture
Capture the received HTTP response status code. Status capture consists of a variable name, followed by a `:`, and the
keyword `status`.
```hurl
GET https://example.org
HTTP/1.1 200
[Captures]
my_status: status
```
### Header capture
Capture a header from the received HTTP response headers. Header capture consists of a variable name, followed by a `:`,
then the keyword `header` and a header name.
```hurl
POST https://example.org/login
[FormParams]
user: toto
password: 12345678
HTTP/1.1 302
[Captures]
next_url: header "Location"
```
### URL capture
Capture the last fetched URL. This is most meaningful if you have told Hurl to follow redirection (see [`[Options]`section][options] or
[`--location` option]). URL capture consists of a variable name, followed by a `:`, and the keyword `url`.
```hurl
GET https://example.org/redirecting
[Options]
location: true
HTTP/* 200
[Captures]
landing_url: url
```
### Cookie capture
Capture a [`Set-Cookie`] header from the received HTTP response headers. Cookie
capture consists of a variable name, followed by a `:`, then the keyword `cookie`
and a cookie name.
```hurl
GET https://example.org/cookies/set
HTTP/1.0 200
[Captures]
session-id: cookie "LSID"
```
Cookie attributes value can also be captured by using the following format:
`<cookie-name>[cookie-attribute]`. The following attributes are supported:
`Value`, `Expires`, `Max-Age`, `Domain`, `Path`, `Secure`, `HttpOnly` and `SameSite`.
```hurl
GET https://example.org/cookies/set
HTTP/1.0 200
[Captures]
value1: cookie "LSID"
value2: cookie "LSID[Value]" # Equivalent to the previous capture
expires: cookie "LSID[Expires]"
max-age: cookie "LSID[Max-Age]"
domain: cookie "LSID[Domain]"
path: cookie "LSID[Path]"
secure: cookie "LSID[Secure]"
http-only: cookie "LSID[HttpOnly]"
same-site: cookie "LSID[SameSite]"
```
### Body capture
Capture the entire body (decoded as text) from the received HTTP response
```hurl
GET https://example.org/home
HTTP/1.1 200
[Captures]
my_body: body
```
### Bytes capture
Capture the entire body (as a raw bytestream) from the received HTTP response
```hurl
GET https://example.org/data.bin
HTTP/1.1 200
[Captures]
my_data: bytes
```
### XPath capture
Capture a [XPath] query from the received HTTP body decoded as a string.
Currently, only XPath 1.0 expression can be used.
```hurl
GET https://example.org/home
# Capture the identifier from the dom node <div id="pet0">5646eaf23</div
HTTP/1.1 200
[Captures]
ped-id: xpath "normalize-space(//div[@id='pet0'])"
# Open the captured page.
GET https://example.org/home/pets/{{pet-id}}
HTTP/1.1 200
```
XPath captures are not limited to node values (like string, or boolean); any
valid XPath can be captured and asserted with variable asserts.
```hurl
# Test that the XML endpoint return 200 pets
GET https://example.org/api/pets
HTTP/* 200
[Captures]
pets: xpath "//pets"
[Asserts]
variable "pets" count == 200
```
### JSONPath capture
Capture a [JSONPath] query from the received HTTP body.
```hurl
POST https://example.org/api/contact
[FormParams]
token: {{token}}
email: toto@rookie.net
HTTP/1.1 200
[Captures]
contact-id: jsonpath "$['id']"
```
> Explain that the value selected by the JSONPath is coerced to a string when only one node is selected.
As with [XPath captures], JSONPath captures can be anything from string, number, to object and collections.
For instance, if we have a JSON endpoint that returns the following JSON:
```
{
"a_null": null,
"an_object": {
"id": "123"
},
"a_list": [
1,
2,
3
],
"an_integer": 1,
"a float": 1.1,
"a_bool": true,
"a_string": "hello"
}
```
We can capture the following paths:
```hurl
GET https://example.org/captures-json
HTTP/1.0 200
[Captures]
an_object: jsonpath "$['an_object']"
a_list: jsonpath "$['a_list']"
a_null: jsonpath "$['a_null']"
an_integer: jsonpath "$['an_integer']"
a_float: jsonpath "$['a_float']"
a_bool: jsonpath "$['a_bool']"
a_string: jsonpath "$['a_string']"
all: jsonpath "$"
```
### Regex capture
Capture a regex pattern from the HTTP received body, decoded as text.
```hurl
GET https://example.org/helloworld
HTTP/1.0 200
[Captures]
id_a: regex "id_a:([0-9]+)!"
id_b: regex "id_b:(\\d+)!"
name: regex "Hello ([a-zA-Z]+)!"
```
Pattern of the regex query must have at least one capture group, otherwise the
capture will fail. Metacharacters beginning with a backslash in the pattern
(like `\d`, `\s`) must be escaped: `regex "(\\d+)!"` will capture one or more digit.
### Variable capture
Capture the value of a variable into another.
```hurl
GET https://example.org/helloworld
HTTP/1.0 200
[Captures]
in: body
name: variable "in" regex "Hello ([a-zA-Z]+)!"
```
### Duration capture
Capture the response time of the request in ms.
```hurl
GET https://example.org/helloworld
HTTP/1.0 200
[Captures]
duration_in_ms: duration
```
## Filters
Optionally, query can be refined using filters `count` and `regex`.
<div class="schema-container u-font-size-0 u-font-size-1-sm u-font-size-3-md">
<div class="schema">
<span class="schema-token schema-color-1">my_var<span class="schema-label">variable</span></span>
<span> : </span>
<span class="schema-token schema-color-2">xpath "string(//h1)"<span class="schema-label">query</span></span>
<span class="schema-token">regex "(\\d+)"<span class="schema-label">filter (optional)</span></span>
</div>
</div>
### Count filter
Returns the count of a collection.
```hurl
GET https://pets.org/cats/cutest
HTTP/1.0 200
[Captures]
cats_size: jsonpath "$.cats" count
```
### Regex filter
```hurl
GET https://pets.org/cats/cutest
HTTP/1.0 200
# Cat name are structured like this `meow + id`: for instance `meow123456`
[Captures]
id: jsonpath "$.cats[0].name" regex "meow(\\d+)"
```
Pattern of the regex filter must have at least one capture group, otherwise the
capture will fail. Metacharacters beginning with a backslash in the pattern
(like `\d`, `\s`) must be escaped: `regex "(\\d+)!"` will capture one or more digit.
[CSRF tokens]: https://en.wikipedia.org/wiki/Cross-site_request_forgery
[variable values]: /docs/manual.md#variable
[templates]: /docs/templates.md
[`Set-Cookie`]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Set-Cookie
[XPath]: https://en.wikipedia.org/wiki/XPath
[JSONPath]: https://goessner.net/articles/JsonPath/
[XPath captures]: #xpath-capture
[Javascript-like Regular expression syntax]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
[options]: /docs/request.md#options
[`--location` option]: /docs/manual.md#location