从C＃返回带有数字键的列表

Question

My code is as follows:

var aaData = 
    ctx.PaymentRates
        .Where(x => x.ServiceRateCodeId == new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96"))
        .Select(x => new 
        {
            Id = x.Id
        }).ToList();

It generates the following JSON when converted using Json(aaData); :

"aaData":[
    {"Id":"ab57fc9d-ffb7-4a12-8c5c-03f36b4ef1fe"},
    {"Id":"4c1e9776-5d64-4054-a9c9-0fc8b8b8e8a1"}
    etc.
]

However, I would like to return keys before the values, like so:

"aaData":[
    [0] => {"Id":"ab57fc9d-ffb7-4a12-8c5c-03f36b4ef1fe"},
    [1] => {"Id":"4c1e9776-5d64-4054-a9c9-0fc8b8b8e8a1"}
    etc.
]

Edit: I am not sure of the proper syntax - the point is, I just want numeric keys.

How can I do this in C#?

Answer 1

JSON uses implicit indexing - meaning the order of elements in an array is preserved, so you can infer the "index" from the order of elements when you retrieve them.

If you need to include an "index" element, you'll have to make it an attribute of the array element:

var aaData = 
    ctx.PaymentRates
        .Where(x => x.ServiceRateCodeId == new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96"))
        .Select((x, i) => new 
        {
            Index = i,
            Id = x.Id
        }).ToList();

Your JSON should look something like:

"aaData":[
    {"Index":"0", "Id":"ab57fc9d-ffb7-4a12-8c5c-03f36b4ef1fe"},
    {"Index":"1", "Id":"4c1e9776-5d64-4054-a9c9-0fc8b8b8e8a1"}
    etc.
]

Answer 2

It is not a matter of whether it is possible in C# or not, it is more a matter of the fact that JSON has a certain format and the format you would like to achieve is not compliant with JSON.

So in case you would like to achieve a result in such a format you would have to build your own format (but then you would also have to create your own serializers, deserializers, etc - in general quite a lot of hassle).

Answer 3

Do you mean the index? Here's one way you can get it

var counter = 0;
var aaData = 
    ctx.PaymentRates
        .Where(x => x.ServiceRateCodeId == new Guid("BBCE42CB-56E3-4848-B396-4656CCE3CE96"))
        .Select(x => new 
        {
            Index = counter++,
            Id = x.Id
        }).ToList();

Answer 4

In order to do what you wish you would have to use a Dictionary instead of a List. Doing:

int idx = 0;
var dict = aaData.ToDictionary(k => "" + idx++);

will return provide you with the following valid JSON

"aaData":{
    "0" : {"Id":"ab57fc9d-ffb7-4a12-8c5c-03f36b4ef1fe"},
    "1" : {"Id":"4c1e9776-5d64-4054-a9c9-0fc8b8b8e8a1"}
    etc.
}

note the fact that the keys are strings that contain numeric values. Numeric values are not supported as keys .