哪里出错了？

ajax in view

$.ajax({       //Default Dose
    data    : {'cropid':cropid},
    type    : 'post',
    url     : "<?php echo base_url();?>index.php/user/cropConfig/getDose",
    dataType: 'json',
    success :function(response) {
        console.log(response);
        console.log("Hello");
    },
    error: function(xhr, status, error) {
        var err = eval("(" + xhr.responseText + ")");
        alert(err.Message);
    }
})

code in controller

    function getDose()  //this will bring default configured crop Dose
    {
        $user=$this->session->userdata('user');
        //$districtid=$user['district_id'];
        $cropid=$this->input->post('cropid');
        $dose=array();
        $dose=$this->cropConfig_model->getDose($cropid);
        print_r($dose);
        echo(json_encode($dose));
    }

Output from controller:

Array ( [0] => Array ( [dosenumber] => 1 [per] => 20 [das] => 0 ) [1] => Array ( [dosenumber] => 2 [per] => 40 [das] => 30 ) [2] => Array ( [dosenumber] => 3 [per] => 40 [das] => 30 ) ) [{"dosenumber":"1","per":"20","das":"0"},{"dosenumber":"2","per":"40","das":"30"},{"dosenumber":"3","per":"40","das":"30"}]

code in model

function getDose($cropid){       //this will bring default configured crop Dose
    $this->db->select('*');
    $this->db->from('cropdose');
    $this->db->where('cropid',$cropid);
    $queryCropDose = $this->db->get();
    return $queryCropDose->result_array();
}

I am getting data successfuly but responce in ajax is not responding giving error which i am not able solve.

1st : You need to return the response only json data not other data Because you setup the dataType:"json" so comment this line .then ajax will work

 //print_r($dose); 

It will work Now.

Try remove the print_r line from your controller?

function getDose() {
$user=$this->session->userdata('user');
//$districtid=$user['district_id'];
$cropid=$this->input->post('cropid');
$dose=array();
$dose=$this->cropConfig_model->getDose($cropid);
//print_r($dose); <--Here!!
echo(json_encode($dose));

}