How do I convert the string formatted array to an actual array in the Controller?

Question

I am submitting a form to the controller, the form consists of properties which one of them is an array.

$("#parsedQuestions input").val(JSON.stringify(questionsArr));
var formData = JSON.stringify($("#trainingForm").serialize());

$.ajax({
    type: "POST",
    url: '@Url.Action("SaveTraining", "Training")',
    data:  formData,
    error: function(jqXHR, textStatus, errorMessage) {
        console.log(errorMessage);
    },
    success: function(data) {console.log(data)} 
});

The questionsArr is an array, but it is being returned as a plain string like this:

"[[\"1\",\"11\",\"111\",\"1111\",\"1111\",\"11111\"],[\"1\",\"22\",\"222\",\"2222\",\"22222\",\"2222222\"]]"

My Controller

public async Task<IActionResult> SaveTraining([FromForm] KII_TrainingModel formData)
{
}

It's a 2-dimensional array supposedly.

In my model, I tried to make this property ParsedQuestions as string[][] and List. But I only get one element, which is the formatted string array.

I have looked everywhere to find a solution but can't find one. Any answers or ideas will be appreciated.

If I don't stringify it, it looks like this:

If I do, then it returns this:

"[[\"1\",\"11\",\"111\",\"1111\",\"1111\",\"11111\"],[\"1\",\"22\",\"222\",\"2222\",\"22222\",\"2222222\"]]"

Any suggestions even as to how to convert this string to an actual array?

It's JSON, because you specifically used JSON.stringify to convert it to JSON. Thus, you need to use a JSON module to decode it back to its component parts. — Tim Roberts
– Tim Roberts, Commented Sep 10, 2022 at 1:36
Even without the JSON.stringify it's being submitted as a string — Sophie
– Sophie, Commented Sep 10, 2022 at 1:38

Yong Shun · Accepted Answer · 2022-09-10 01:45:07Z

1

I believe that the way that sets the array into the text field and retrieves it from the form, the array will be in string value.

Instead, you have to append the array into formData via FormData.append() similar to below:

for (let i = 0; i < questionsArr.length; i++) {
    for (let j = 0; j < questionsArr[i].length; j++) {
        formData.append(`ParsedQuestions[${i}][${j}]`, questionsArr[i][j]);
    }
}

And this line is no longer needed:

$("#parsedQuestions input").val(JSON.stringify(questionsArr));

answered Sep 10, 2022 at 1:45

Yong Shun

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user13793747 · Accepted Answer · 2022-09-10 01:48:57Z

-1

I wrote this as a sample: you can access the data indexing into both arrays.

    let ar = [["1", "11", "111", "1111", "1111", "11111"], ["1", "22", "222", "2222", "22222", "2222222"]]
let ans =    ar[0][2];
console.log(ans);

answered Sep 10, 2022 at 1:48

user13793747

1 Comment

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