I'm developing a website with express and ejs. I got into a trouble where i need to call an api via ajax. The problem is on a button onclick i'm passing two values to ajax data. but it gives error ,i tried a lot of ways and i'm messed up. i'm a newbie , find my code below.

    const parsedData = JSON.parse(localStorage.getItem('myData'));
    
   
    const container = document.getElementById('s1');
 
    parsedData.data.rows.forEach((result, idx) => {
      
     var a = result.master_id;
     var b = result.session_name;
     console.log(a,b,"a","b")
     
   
    var userData = {"pid":a,"session" :b};
     console.log(userData,"userData");
    sessionStorage.setItem("user", JSON.stringify(userData));
    console.log(userData,"data for api");

     const card = document.createElement('div');
     card.classList = 'card';

  
  const content = `
  <div class="row">
      <div class="card-body"  onclick="graphApi()">
  </div>
  </div>


  `;


  container.innerHTML += content;
});

function graphApi(){
       
      var apiValue =JSON.parse( sessionStorage.getItem("user"));
       console.log(apiValue, "value from card");
       

        $.ajax({
        type: "POST",
        data:  apiValue,
        dataType:"json",
        
        url: "http://localhost:5000/graphFromcsv",                      
        success: function(data) {
        console.log(data,"graph api");
}
  error: function(err){
          alert("graph api failed to load");
          console.log(err);
        },
});

i'm always getting this pid in api value undefined and 400 badrequest . but if i use raw data like,

{
    "pid":"WE6",
    "session":"W.csv"
}

instead of apiValue my ajax is success and i'm gettig the data. i'm using this data to plot a multiple line graph. Any help is appreciated.