framework/data/ActiveDataFilter.php
protected function buildAttributeCondition($attribute, $condition)
    {
        if (is_array($condition)) {
            $parts = [];
            foreach ($condition as $operator => $value) {
                if (isset($this->operatorTypes[$operator])) {
                    if (isset($this->conditionBuilders[$operator])) {
                        $method = $this->conditionBuilders[$operator];
                        if (is_string($method)) {
                            $callback = [$this, $method];
                        } else {
                            $callback = $method;
                        }
                        $parts[] = $callback($operator, $value, $attribute);
                    } else {
                        $parts[] = $this->buildOperatorCondition($operator, $value, $attribute);
                    }
                }
            }

            if (!empty($parts)) {
                if (count($parts) > 1) {
                    return array_merge(['AND'], $parts);
                }
                return array_shift($parts);
            }
        }

        return [$attribute => $this->filterAttributeValue($attribute, $condition)];
    }
protected function buildAttributeCondition($attribute, $condition)
    {
        if (is_array($condition)) {
            $parts = [];
            foreach ($condition as $operator => $value) {
                if (isset($this->operatorTypes[$operator])) {
                    if (isset($this->conditionBuilders[$operator])) {
                        $method = $this->conditionBuilders[$operator];
                        if (is_string($method)) {
                            $callback = [$this, $method];
                        } else {
                            $callback = $method;
                        }
                        $parts[] = $callback($operator, $value, $attribute);
                    } else {
                        $parts[] = $this->buildOperatorCondition($operator, $value, $attribute);
                    }
                }
            }

            if (!empty($parts)) {
                if (count($parts) > 1) {
                    return array_merge(['AND'], $parts);
                }
                return array_shift($parts);
            }
        }

        return [$attribute => $this->filterAttributeValue($attribute, $condition)];
    }
Builds search condition for a particular attribute.
@param string $attribute search attribute name.
@param mixed $condition search condition.
@return array actual condition.