Crow/docs/guides/query-string.md

A query string is the part of the URL that comes after a `?` character, it is usually formatted as `key=value&otherkey=othervalue`.
<br><br>

Crow supports query strings through `crow::request::url_params`. The object is of type `crow::query_string` and can has the following functions:<br>

## get(name)
Returns the value (as char*) based on the given key (or name). Returns `nullptr` if the key is not found.
## pop(name)
<span class="tag">[:octicons-feed-tag-16: v0.3](https://github.com/CrowCpp/Crow/releases/v0.3)</span>


Works the same as `get`, but removes the returned value.
!!! note

    `crow::request::url_params` is a const value, therefore for pop (also pop_list and pop_dict) to work, a copy needs to be made.

## get_list(name)
A URL can be `http://example.com?key[]=value1&key[]=value2&key[]=value3`. Using `get_list("key")` on such a URL returns an `std::vector<std::string>` containing `[value1, value2, value3]`.<br><br>

`#!cpp get_list("key", false)` can be used to parse `http://example.com?key=value1&key=value2&key=value3`
## pop_list(name)
<span class="tag">[:octicons-feed-tag-16: v0.3](https://github.com/CrowCpp/Crow/releases/v0.3)</span>


Works the same as `get_list` but removes all instances of values having the given key (`use_brackets` is also available here).
## get_dict(name)
Returns an `std::unordered_map<std::string, std::string>` from a query string such as `?key[sub_key1]=value1&key[sub_key2]=value2&key[sub_key3]=value3`.<br>
The key in the map is what's in the brackets (`sub_key1` for example), and the value being what's after the `=` sign (`value1`). The name passed to the function is not part of the returned value.
## pop_dict(name)
<span class="tag">[:octicons-feed-tag-16: v0.3](https://github.com/CrowCpp/Crow/releases/v0.3)</span>


Works the same as `get_dict` but removing the values from the query string.
!!! warning

    if your query string contains both a list and dictionary with the same key, it is best to use `pop_list` before either `get_dict` or `pop_dict`, since a map cannot contain more than one value per key, each item in the list will override the previous and only the last will remain with an empty key.

<br><br>
For more information take a look [here](../../reference/classcrow_1_1query__string.html).
updated documentation in mkdocs and doxygen 2022-03-23 22:55:46 +00:00			A query string is the part of the URL that comes after a `?` character, it is usually formatted as `key=value&otherkey=othervalue`.
Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00			`<br><br>`

			Crow supports query strings through `crow::request::url_params`. The object is of type `crow::query_string` and can has the following functions:<br>
added creating qs from request body functionality + updated doc 2022-05-20 19:36:32 +00:00
multiple docs changes: Added meta tags for homepage Added meta description generator Removed usages of <h1> (mkdocs-material doesn't reconize more than 1) added space after # (markdown proper syntax) removed pip3 command from pull request CI 2021-11-06 08:54:29 +00:00			`## get(name)`
Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00			Returns the value (as char*) based on the given key (or name). Returns `nullptr` if the key is not found.
multiple docs changes: Added meta tags for homepage Added meta description generator Removed usages of <h1> (mkdocs-material doesn't reconize more than 1) added space after # (markdown proper syntax) removed pip3 command from pull request CI 2021-11-06 08:54:29 +00:00			`## pop(name)`
improved "introduced in" statements 2022-05-12 21:49:52 +00:00			`<span class="tag">[:octicons-feed-tag-16: v0.3](https://github.com/CrowCpp/Crow/releases/v0.3)</span>`


Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00			Works the same as `get`, but removes the returned value.
			`!!! note`

			`crow::request::url_params` is a const value, therefore for pop (also pop_list and pop_dict) to work, a copy needs to be made.

multiple docs changes: Added meta tags for homepage Added meta description generator Removed usages of <h1> (mkdocs-material doesn't reconize more than 1) added space after # (markdown proper syntax) removed pip3 command from pull request CI 2021-11-06 08:54:29 +00:00			`## get_list(name)`
updated documentation in mkdocs and doxygen 2022-03-23 22:55:46 +00:00			A URL can be `http://example.com?key[]=value1&key[]=value2&key[]=value3`. Using `get_list("key")` on such a URL returns an `std::vector<std::string>` containing `[value1, value2, value3]`.<br><br>
Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00
			`#!cpp get_list("key", false)` can be used to parse `http://example.com?key=value1&key=value2&key=value3`
multiple docs changes: Added meta tags for homepage Added meta description generator Removed usages of <h1> (mkdocs-material doesn't reconize more than 1) added space after # (markdown proper syntax) removed pip3 command from pull request CI 2021-11-06 08:54:29 +00:00			`## pop_list(name)`
improved "introduced in" statements 2022-05-12 21:49:52 +00:00			`<span class="tag">[:octicons-feed-tag-16: v0.3](https://github.com/CrowCpp/Crow/releases/v0.3)</span>`


Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00			Works the same as `get_list` but removes all instances of values having the given key (`use_brackets` is also available here).
multiple docs changes: Added meta tags for homepage Added meta description generator Removed usages of <h1> (mkdocs-material doesn't reconize more than 1) added space after # (markdown proper syntax) removed pip3 command from pull request CI 2021-11-06 08:54:29 +00:00			`## get_dict(name)`
Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00			Returns an `std::unordered_map<std::string, std::string>` from a query string such as `?key[sub_key1]=value1&key[sub_key2]=value2&key[sub_key3]=value3`.<br>
			The key in the map is what's in the brackets (`sub_key1` for example), and the value being what's after the `=` sign (`value1`). The name passed to the function is not part of the returned value.
multiple docs changes: Added meta tags for homepage Added meta description generator Removed usages of <h1> (mkdocs-material doesn't reconize more than 1) added space after # (markdown proper syntax) removed pip3 command from pull request CI 2021-11-06 08:54:29 +00:00			`## pop_dict(name)`
improved "introduced in" statements 2022-05-12 21:49:52 +00:00			`<span class="tag">[:octicons-feed-tag-16: v0.3](https://github.com/CrowCpp/Crow/releases/v0.3)</span>`


Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00			Works the same as `get_dict` but removing the values from the query string.
documented CROW_FEATURES 2022-04-07 12:42:47 +00:00			`!!! warning`
Quality of life improvements Added pop() method to query_string, same as get(), but removes the item from the querystring Added std::string() operator to json::rvalue (allows std::string(json["abc"]), which returns any value that isn't a container to string) Added lo() method to json::rvalue, returns a vector of json::rvalue containing whatever a json object or list has (difference being a list has no keys) Added keys() method to json::rvalue, returns a vector of std::string containing the keys of a json object Made json::wvalue use either std::map or std::unordered_map instead of just std::unordered_map Added copy constructor to json::wvalue Added size() method to json::wvalue, returns 1 or the size of the json list. Added constructor to create json::wvalue from std::vector Added keys() method to query_string Documented query_string and improved json doc Made tests and examples for all the additions 2021-05-12 12:45:55 +00:00
			if your query string contains both a list and dictionary with the same key, it is best to use `pop_list` before either `get_dict` or `pop_dict`, since a map cannot contain more than one value per key, each item in the list will override the previous and only the last will remain with an empty key.

			`<br><br>`
			`For more information take a look [here](../../reference/classcrow_1_1query__string.html).`