params_ref

A view representing query parameters in a URL

Synopsis


                class params_ref
                    : public params_base;

Declared in file <boost/url/params_ref.hpp> at line 80

Types

Name	Description
iterator

Types

Name	Description
const_iterator	iterator
value_type	The value type
reference	The reference type
const_reference	The reference type
size_type	An unsigned integer type to represent sizes.
difference_type	A signed integer type used to represent differences.

Member Functions

Name	Description
buffer	Return the referenced character buffer.
empty	Return true if there are no params
size	Return the number of params
begin	Return an iterator to the beginning
end	Return an iterator to the end
contains	Return true if a matching key exists
count	Return the number of matching keys
find	Find a matching key
find	Find a matching key
find_last	Find a matching key
find_last	Find a matching key
params_ref	Constructor
params_ref	Constructor
operator=	Assignment
operator=	Assignment
operator params_view	Conversion
url	Return the referenced url
clear	Clear the contents of the container
assign	Assign elements
assign	Assign elements
append	Append elements
append	Append elements
append	Append elements
insert	Insert elements
insert	Insert elements
insert	Insert elements
erase	Erase elements
erase	Erase elements
erase	Erase elements
replace	Replace elements
replace	Replace elements
replace	Replace elements
unset	Remove the value on an element
set	Set a value
set	Set a value

Description

Objects of this type are used to interpret the query parameters as a bidirectional view of key/value pairs. The view does not retain ownership of the elements and instead references the original url. The caller is responsible for ensuring that the lifetime of the referenced url extends until it is no longer referenced. The view is modifiable; calling non-const members causes changes to the referenced url.

Percent escapes in strings returned when dereferencing iterators are automatically decoded. Reserved characters in strings supplied to modifier functions are automatically percent-escaped.

Example


url u( "?first=John&last=Doe" );

params_ref p = u.params();

Iterator Invalidation

Changes to the underlying character buffer can invalidate iterators which reference it. Modifications made through the container invalidate some or all iterators:

append : Only `end()`.

assign, clear, `operator=` : All elements.

erase : Erased elements and all elements after (including `end()`).

insert : All elements at or after the insertion point (including `end()`).

replace, set : Modified elements and all elements after (including `end()`).