[#boost-urls-url_base-set_params]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/url_base.adoc[url&lowbar;base]::set&lowbar;params
:relfileprefix: ../../../
:mrdocs:

Set the query params

== Synopsis

Declared in `&lt;https://www.github.com/boostorg/url/blob/develop/include/boost/url/url_base.hpp#L2356[boost&sol;url&sol;url&lowbar;base&period;hpp]&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/url_base.adoc[url&lowbar;base]&
set&lowbar;params(
    std::initializer&lowbar;list&lt;param&lowbar;view&gt; ps,
    xref:boost/urls/encoding_opts.adoc[encoding&lowbar;opts] opts = &lcub;&rcub;) noexcept;
----

== Description

This sets the query params to the list of param&lowbar;view, which can be empty&period;

An empty list of params is distinct from having no params&period;

Reserved characters in the string are percent&hyphen;escaped in the result&period;

== Example

[,cpp]
----
assert( url( "http://example.com" ).set_params( {"id", "42"} ).query() == "id=42" );
----
== Postconditions

[,cpp]
----
this->has_query() == true
----
== Exception Safety

Strong guarantee&period; Calls to allocate may throw&period;

== Complexity

Linear&period;

== BNF

[,cpp]
----
query           = *( pchar / "/" / "?" )

query-param     = key [ "=" value ]
query-params    = [ query-param ] *( "&" query-param )
----
== Specification

* https://datatracker.ietf.org/doc/html/rfc3986#section-3.4
            >3.4.  Query (rfc3986)</a>
        @li <a href=[&colon;&sol;&sol;en&period;wikipedia&period;org&sol;wiki&sol;Query&lowbar;string&quot;            &gt;Query string (Wikipedia)]

== Return Value

`&ast;this`

== Parameters

[cols=2]
|===
| Name
| Description
| *ps*
| The params to set&period;
| *opts*
| The options for encoding&period;
|===

== See Also

xref:boost/urls/url_base/encoded_params-0b.adoc[`encoded&lowbar;params`], xref:boost/urls/url_base/remove_query.adoc[`remove&lowbar;query`], xref:boost/urls/url_base/set_encoded_query.adoc[`set&lowbar;encoded&lowbar;query`], xref:boost/urls/url_base/set_query.adoc[`set&lowbar;query`]&period;


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