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SharePoint: Get content type, which is associated with the current request

December 29th, 2010 Admin Leave a comment Go to comments

     In my project I’ve created custom display/edit/new forms for every usable list. The easiest way to get a SPContentType-instance, which is connected with the current Page, is a property SPContext.Current.ListItem.ContentType. Sometimes, I have to get the current content type inside OnInit-method of page lifecycle. If we edit or display an existed list item (edit/display-forms), we can do it easily, because SPContext.Current.ListItem is already defined and accessible. But, if we create a new list item (new-form), we don’t have a valid SPContext.Current.ListItem inside OnInit, because none is created yet. The following table demonstrates when (starting from what method of page lifecycle) SPContext.Current.ListItem.ContentType is already accessible:

Form

Accessible starting from

Edit OnInit
Display OnInit
New OnLoad

     To get the current content type inside OnInit of New-form, at first we need to extract ContentTypeId from query-string of Page.Request, then having ContentTypeId we receive the instance of SPContentType. It should be noted that SPContext has an internal method GetContentTypeThroughQueryString, which provides SPCOntentType-instance based on id of content type in the query-string.

     Of course, we can invoke this internal method through .Net Reflexion, but I prefer rewriting such methods, when it’s possible. So, now I have my own GetContentTypeThroughQueryString method:

protected SPContentType GetContentTypeThroughQueryString()
{
    string cntTypeIdStr = HttpContext.Current.Request.QueryString["ContentTypeId"];
    if (!string.IsNullOrEmpty(cntTypeIdStr))
    {
        try
        {
            SPContentType spContentType = null;
            if (cntTypeIdStr.StartsWith("0x"))
            {
                SPContentTypeId contentTypeId = new SPContentTypeId(cntTypeIdStr);
                spContentType = SPContext.Current.List.ContentTypes[contentTypeId];
                if (spContentType == null)
                    spContentType = SPContext.Current.List.ContentTypes[SPContext.Current.List.ContentTypes.BestMatch(contentTypeId)];
            }
            else
            {
                using (StringWriter writer = new StringWriter(CultureInfo.InvariantCulture))
                {
                    int num = int.Parse(cntTypeIdStr, writer.FormatProvider);
                    spContentType = SPContext.Current.List.ContentTypes[num];
                }
            }

            return spContentType;
        }
        catch{}
    }
    return null;
}

     And the result method, that returns the current content type associated with the current request, is

protected SPContentType GetCurrentContentType()
{
    if (SPContext.Current.ListItem != null && SPContext.Current.ListItem.ContentType != null)
        return SPContext.Current.ListItem.ContentType;

    // try to get content type through query string
    return GetContentTypeThroughQueryString();
}

     GetCurrentContentType can be invoked inside any method of page lifecycle, even inside OnInit.

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