Question

I am building a Web API that will be inserting some values into a Microsoft SQL Server database.

This APIs eventual usage will be in a JAVA Spring application.

I don’t want to put the “carriage before the horse,” so as a POC, I wanted to prove to myself first that I can call my Web API from a simple web page.

Essentially, my simple web page has some text input fields and when I click on a button, I validate the text fields and then create a JSON string out of them. Next I have an Ajax call that passes this JSON string to my controller. My controller in .NET land receives my request, but chokes with the following error –

An error has occurred.”,”ExceptionMessage”:”String or binary data would be truncated.

And the stack trace follows.

at System.Data.SqlClient.SqlInternalConnection.OnError… blah blah

I think the problem is with several of the columns that I am attempting to insert into.

They are of type VARCHAR(1) and have the NOT NULL property in SQL Server.

On my simple web page, I never created a text input for these values. Instead, I figured that I could stick those values in when I am doing the actual INSERT on the server. Incidentally, I am using the TableAdapter to handle all my database connections, etc…

Code that makes all this happen is as follows:

//JQUERY - collecting the input and generating the JSON
$('#pythonIsActive').is(':checked') ? activeCourse = 'Y' : activeCourse = 'N';  
        $('#pythonRequiresSecurityClearance').is(':checked') ? clearanceRequired = 'Y' : clearanceRequired = 'N';
        $('#pythonOfferedFall').is(':checked') ? fall = 'Y' : fall = 'N';
        $('#pythonOfferedWinter').is(':checked') ? winter = 'Y' : winter = 'N';
        $('#pythonOfferedSpring').is(':checked') ? spring = 'Y' : spring = 'N';
        $('#pythonOfferedSummer').is(':checked') ? summer = 'Y' : summer = 'N';
        $('#pythonIsTentative').is(':checked') ? tenativeCourse = 'Y' : tenativeCourse = 'N';

        var Course = {
            CourseID: $('#pythonCourseId').val(),
            CourseLongName: $('#pythonLongName').val(),
            IsActiveCourse: activeCourse,
            Description: $('#pythonCourseDescription').val(),
            DepartmentID: $('#pythonDepartmentId').val(),
            LabHours: $('#pythonLabHours').val(),
            LectureHours: $('#pythonLectureHours').val(),
            CourseShortName: $('#pythonShortName').val(),
            EffectiveYear: $('#pythonEffectiveYear').val(),
            EffectiveQuarter: $('#pythonEffectiveQuarter').val(),
            IsClearanceRequired: $('#pythonRequiresSecurityClearance').val(),
            ClearanceRequired: $('#pythonSecurityClearanceRequired').val(),
            CourseCoordinatorID: $('#pythonCoordinatorID').val(),
            IsOfferedQ1: fall,
            IsOfferedQ2: winter,
            IsOfferedQ3: spring,
            IsOfferedQ4: summer,
            Prerequisite1: $('#pythonPrerequisite1').val(),
            Prerequisite2: $('#pythonPrerequisite2').val(),
            Prerequisite3: $('#pythonPrerequisite3').val(),
            IsTentative: tenativeCourse,
            Prerequisites: $('#pythonPrerequisites').val()
        };
        courseDataToPost = JSON.stringify(Course);
        return courseDataToPost;

Next, I will pass this JSON String to my AJAX CALL like so –

$.ajax({
    type: "POST",
    url: "/api/courses",
    cache: false,
    contentType: "application/json; charset=utf-8",
    async: true,
    data: dataToPost,
    dataType: "json",
    success: function () {
      alert("Success!");
    },
    error: function (x, e) {
      alert("The call to the server side FAILED. " + x.responseText);
    }
});

So, this successfully routes the request to the correct controller’s method here –

    // POST /api/courses
    [HttpPost]
    public void Post(pythonCourse course)
    {
        var postTableAdapter = new tnpCourseTableAdapter();
        decimal zero = 0;
        string no = "N";

        try
        {
            postTableAdapter.Insert(course.CourseID, course.CourseLongName, 
                                    course.IsActiveCourse, course.Description,
                                    course.DepartmentID, course.LabHours, 
                                    course.LectureHours, course.CourseShortName,
                                    course.EffectiveYear, course.EffectiveQuarter, 
                                    course.IsClearanceRequired,
                                    course.ClearanceRequired, 
                                    course.CourseCoordinatorID, course.IsOfferedQ1,
                                    course.IsOfferedQ2, course.IsOfferedQ3, 
                                    course.IsOfferedQ4, course.Prerequisite1,
                                    course.Prerequisite2, course.Prerequisite3, 
                                    course.IsTentative, zero, zero, null,
                                    no, no, no, null, null, null, null);
        }
        catch (Exception)
        {
            throw;
        }            
    }            

When I arrive here in the server code, the debugger stops on the catch block and gives the “String or binary data…” error.

Notice in my list of arguments that I pass 3 instances of the string no.

These arguments are strings, but SQL Server is expecting VARCHAR(1).

Is this what is causing my grief, or is there something else going on?

Answer 1

This error means you’re putting too much data into the column. Your column expects a single character string.

So the error means if you put no into the column.. it will be truncated to n.

Another example: If the column was VARCHAR(5) and you inserted “Hello World!”, it would warn that it can only insert “Hello”.