Web API post parameter

Question

I currently have an issue with a webapi call. I want to download and open a logfile with my ApiController. I use a javascript function to post a filename to my controller.

Here is a helper function to post the parameter (answer from dystroy): How to replace window.open(...) with a POST

Now when I use a simple string as parameter in my controller I can’t get the parameter, it is always null.

public HttpResponseMessage PostDownloadLogFile([FromBody]string psFileName)
{
    //psFileName is always null

But if I use HttpReqeustMessage as parameter and read the form data from my request it is no problem and it works.

public HttpResponseMessage PostDownloadLogFile(HttpRequestMessage poRequest)
{
    var loFormData = poRequest.Content.ReadAsFormDataAsync().Result;
    string psFileName = loFormData["psFileName"]; //psFileName is set correct

Is there a solution to get the parameter with a simple parameter in my controller?

Update

This is my javascript helper function:

var loOpenWindow = function (psMethode, psUrl, poData, psTarget) {
    var loForm = document.createElement("form");
    loForm.action = psUrl;
    loForm.method = psMethode;
    loForm.target = psTarget || "_self";
    if (poData) {
        for (var lsKey in poData) {
            var loInput = document.createElement("textarea");
            loInput.name = lsKey;
            loInput.value = typeof poData[lsKey] === "object" ? JSON.stringify(poData[lsKey]) : poData[lsKey];
            loForm.appendChild(loInput);
        }
    }
    loForm.style.display = "none";
    document.body.appendChild(loForm);
    loForm.submit();
};

Call it:

helper.openWindow("POST", apiRoutes.URLS.ApiPostDownloadLogFile, { "psFilename": $scope.data.showLogEntry.FullName });

There should be no problem from the client side code, because the controller methode with HttpReqeustMessage works without problems.

Here is the browser request: enter image description here

What does the data you're sending to the controller method look like? — pixelbadger, Feb 20 '15 at 16:02
That is a javascript help function from this post: http://stackoverflow.com/questions/17793183/how-to-replace-window-open-with-a-post — PinBack, Feb 20 '15 at 16:05
The helper function has four parameters: verb, url, data, and target. What are you passing into the data variable (and all the others for that matter)? — pixelbadger, Feb 20 '15 at 16:07
helper.openWindow("POST", apiRoutes.URLS.ApiPostDownloadLogFile, { "psFilename": $scope.data.showLogEntry.FullName }); — PinBack, Feb 20 '15 at 16:10
What does your clintside code look like that consumes this service? Im betting its a problem with how your formatting the 'data' parameter. — Botonomous, Feb 20 '15 at 16:15
Can you please paste here the browser request? With HTTP headers and body. — Filipe Borges, Feb 20 '15 at 16:16

score 2 · Answer 1 · answered Feb 20 '15 at 16:22

2

Probably the problem is in your client code sending the data.

[FromBody] parameters must be encoded as =value

then, this does not work:

// Value will be null.
$.post('api/values', value);

// Value will be null.
$.post('api/values', { key: value });

But this work:

$.post('api/values', "=" + value);

Try to change your client code to send just =/path/to/your/file in the body.

Reference: http://encosia.com/using-jquery-to-post-frombody-parameters-to-web-api/

answered Feb 20 '15 at 16:22

Filipe Borges

2,712
20
32

I try it but unfortunately the value is still null. I try this: helper.openWindow("POST", apiRoutes.URLS.ApiPostDownloadLogFile, "=" + $scope.data.showLogEntry.FullName); and this: helper.openWindow("POST", apiRoutes.URLS.ApiPostDownloadLogFile, { '': $scope.data.showLogEntry.FullName }); – PinBack Feb 20 '15 at 16:33

score 1 · Accepted Answer · answered Feb 20 '15 at 17:06

Ok I found a solution. If I use a class as parameter and a property with the given name, it seems to work.

public class Param
{
    public string psFileName { get; set; }
}

And

public HttpResponseMessage PostDownloadLogFile(Param poParam)
{
    string psFileName = poParam.psFileName; //psFileName is set correct

This is not really a simple parameter but I can live with this solution.

Web API post parameter

2 Answers2