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    <p>As a method of a <code>COMObject</code>, <code>getElementById</code> is built by <code>win32com</code> dynamically.<br/> On my computer, if url is <a href="http://ieeexplore.ieee.org/xpl/periodicals.jsp" rel="noreferrer">http://ieeexplore.ieee.org/xpl/periodicals.jsp</a>, it will be almost equivalent to </p> <pre><code>def getElementById(self): return self._ApplyTypes_(3000795, 1, (12, 0), (), 'getElementById', None,) </code></pre> <p>If the url is www.baidu.com, it will be almost equivalent to </p> <pre><code>def getElementById(self, v=pythoncom.Missing): ret = self._oleobj_.InvokeTypes(1088, LCID, 1, (9, 0), ((8, 1),),v ) if ret is not None: ret = Dispatch(ret, 'getElementById', {3050F1FF-98B5-11CF-BB82-00AA00BDCE0B}) return ret </code></pre> <p>Obviously, if you pass an argument to the first code, you'll receive a <code>TypeError</code>. But if you try to use it directly, namely, invoke <code>ie.Document.getElementById()</code>, you won't receive a <code>TypeError</code>, but a <code>com_error</code>.<br/></p> <p>Why <code>win32com</code> built the wrong code?<br/> Let us look at <code>ie</code> and <code>ie.Document</code>. They are both <code>COMObject</code>s, more precisely, <code>win32com.client.CDispatch</code> instances. <code>CDispatch</code> is just a wrapper class. The core is attribute <code>_oleobj_</code>, whose type is <code>PyIDispatch</code>.</p> <pre><code>&gt;&gt;&gt; ie, ie.Document (&lt;COMObject InternetExplorer.Application&gt;, &lt;COMObject &lt;unknown&gt;&gt;) &gt;&gt;&gt; ie.__class__, ie.Document.__class__ (&lt;class win32com.client.CDispatch at 0x02CD00A0&gt;, &lt;class win32com.client.CDispatch at 0x02CD00A0&gt;) &gt;&gt;&gt; oleobj = ie.Document._oleobj_ &gt;&gt;&gt; oleobj &lt;PyIDispatch at 0x02B37800 with obj at 0x003287D4&gt; </code></pre> <p>To build <code>getElementById</code>, <code>win32com</code> needs to get the type information for <code>getElementById</code> method from <code>_oleobj_</code>. Roughly, <code>win32com</code> uses the following procedure</p> <pre><code>typeinfo = oleobj.GetTypeInfo() typecomp = typeinfo.GetTypeComp() x, funcdesc = typecomp.Bind('getElementById', pythoncom.INVOKE_FUNC) ...... </code></pre> <p><code>funcdesc</code> contains almost all import information, e.g. the number and types of the parameters.<br/> If url is <a href="http://ieeexplore.ieee.org/xpl/periodicals.jsp" rel="noreferrer">http://ieeexplore.ieee.org/xpl/periodicals.jsp</a>, <code>funcdesc.args</code> is <code>()</code>, while the correc <code>funcdesc.args</code> should be <code>((8, 1, None),)</code>.</p> <p>Long story in short, <code>win32com</code> had retrieved the wrong type information, thus it built the wrong method.<br/> I am not sure who is to blame, PyWin32 or IE. But base on my observation, I found nothing wrong in PyWin32's code. On the other hand, the following script runs perfectly in <em>Windows Script Host</em>.</p> <pre><code>var ie = new ActiveXObject("InternetExplorer.Application"); ie.Visible = 1; ie.Navigate("http://ieeexplore.ieee.org/xpl/periodicals.jsp"); WScript.sleep(5000); ie.Document.getElementById("browse_keyword").value = "Computer"; </code></pre> <p>Duncan has already pointed out IE's compatibility mode can prevent the problem. Unfortunately, it seems it's impossible to enable compatibility mode from a script.<br/> But I found a trick, which can help us bypass the problem.<br/></p> <p>First, you need to visit a good site, which gives us a HTML page, and retrieve a correct <code>Document</code> object from it.<br/></p> <pre><code>ie = win32com.client.DispatchEx('InternetExplorer.Application') ie.Visible = 1 ie.Navigate('http://www.haskell.org/arrows') time.sleep(5) document = ie.Document </code></pre> <p>Then jump to the page which doesn't work</p> <pre><code>ie.Navigate('http://ieeexplore.ieee.org/xpl/periodicals.jsp') time.sleep(5) </code></pre> <p>Now you can access the DOM of the second page via the old <code>Document</code> object.</p> <pre><code>document.getElementById('browse_keyword').value = "Computer" </code></pre> <p>If you use the new <code>Document</code> object, you will get a <code>TypeError</code> again.</p> <pre><code>&gt;&gt;&gt; ie.Document.getElementById('browse_keyword') Traceback (most recent call last): File "&lt;interactive input&gt;", line 1, in &lt;module&gt; TypeError: getElementById() takes exactly 1 argument (2 given) </code></pre>
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