framework/web/Request.php
public function getBodyParams()
    {
        if ($this->_bodyParams === null) {
            if (isset($_POST[$this->methodParam])) {
                $this->_bodyParams = $_POST;
                unset($this->_bodyParams[$this->methodParam]);
                return $this->_bodyParams;
            }

            $rawContentType = $this->getContentType();
            if (($pos = strpos($rawContentType, ';')) !== false) {
                // e.g. text/html; charset=UTF-8
                $contentType = substr($rawContentType, 0, $pos);
            } else {
                $contentType = $rawContentType;
            }

            if (isset($this->parsers[$contentType])) {
                $parser = Yii::createObject($this->parsers[$contentType]);
                if (!($parser instanceof RequestParserInterface)) {
                    throw new InvalidConfigException("The '$contentType' request parser is invalid. It must implement the yii\\web\\RequestParserInterface.");
                }
                $this->_bodyParams = $parser->parse($this->getRawBody(), $rawContentType);
            } elseif (isset($this->parsers['*'])) {
                $parser = Yii::createObject($this->parsers['*']);
                if (!($parser instanceof RequestParserInterface)) {
                    throw new InvalidConfigException('The fallback request parser is invalid. It must implement the yii\\web\\RequestParserInterface.');
                }
                $this->_bodyParams = $parser->parse($this->getRawBody(), $rawContentType);
            } elseif ($this->getMethod() === 'POST') {
                // PHP has already parsed the body so we have all params in $_POST
                $this->_bodyParams = $_POST;
            } else {
                $this->_bodyParams = [];
                mb_parse_str($this->getRawBody(), $this->_bodyParams);
            }
        }

        return $this->_bodyParams;
    }
public function getBodyParams()
    {
        if ($this->_bodyParams === null) {
            if (isset($_POST[$this->methodParam])) {
                $this->_bodyParams = $_POST;
                unset($this->_bodyParams[$this->methodParam]);
                return $this->_bodyParams;
            }

            $rawContentType = $this->getContentType();
            if (($pos = strpos($rawContentType, ';')) !== false) {
                // e.g. text/html; charset=UTF-8
                $contentType = substr($rawContentType, 0, $pos);
            } else {
                $contentType = $rawContentType;
            }

            if (isset($this->parsers[$contentType])) {
                $parser = Yii::createObject($this->parsers[$contentType]);
                if (!($parser instanceof RequestParserInterface)) {
                    throw new InvalidConfigException("The '$contentType' request parser is invalid. It must implement the yii\\web\\RequestParserInterface.");
                }
                $this->_bodyParams = $parser->parse($this->getRawBody(), $rawContentType);
            } elseif (isset($this->parsers['*'])) {
                $parser = Yii::createObject($this->parsers['*']);
                if (!($parser instanceof RequestParserInterface)) {
                    throw new InvalidConfigException('The fallback request parser is invalid. It must implement the yii\\web\\RequestParserInterface.');
                }
                $this->_bodyParams = $parser->parse($this->getRawBody(), $rawContentType);
            } elseif ($this->getMethod() === 'POST') {
                // PHP has already parsed the body so we have all params in $_POST
                $this->_bodyParams = $_POST;
            } else {
                $this->_bodyParams = [];
                mb_parse_str($this->getRawBody(), $this->_bodyParams);
            }
        }

        return $this->_bodyParams;
    }
Returns the request parameters given in the request body.

Request parameters are determined using the parsers configured in [[parsers]] property.
If no parsers are configured for the current [[contentType]] it uses the PHP function `mb_parse_str()`
to parse the [[rawBody|request body]].
@return array the request parameters given in the request body.
@throws \yii\base\InvalidConfigException if a registered parser does not implement the [[RequestParserInterface]].
@see getMethod()
@see getBodyParam()
@see setBodyParams()