Dynamics CRM - Downloading files from notes in C# results in corrupt files with FetchXML - dynamics-crm

Question

I am using Dynamics CRM and am trying to download a file from the notes (annotation) entity. I am getting the Base64 String and converting to Byte[] like this:
Convert.FromBase64String((string)item.Attributes["documentbody"]);
But when I do so and try to open the file it is corrupt. Word Documents and PDFs refuse to open. Images however open partially. Ie. I get about 3/4 of the image but the rest of the image is solid grey.
I am guessing FetchXML is not returning the full string. Is there a way to to do this in FetchXML, overiding the limit? I have Googled but cannot see any mention of FetchXML limit?
There is a similar SO question here: FetchXml Query Returns Trimmed DocumentBody?
But I am not using "distinct" in my query.
Here is what I have so far:
<fetch>
<entity name="annotation" >
<attribute name="documentbody" />
<filter type="and" >
<condition attribute="objectid" operator="eq" value="{D4FFE0CD-CDFA-E711-80E4-005056BA77B6}" />
<condition attribute="isdocument" operator="eq" value="1" />
</filter>
<order attribute="modifiedon" descending="true" />
</entity>
</fetch>

Answer 1

You don't say how you are saving or opening the file, which I suspect is probably the issue.
Re: "I am guessing FetchXML is not returning the full string" - I don't think that is correct, I've not seen this happen.
This is a working example of saving a file to disk.
Exporting Annotation (Note) Attachment
public void ExportDocuments(IOrganizationService service, String filePath)
{
String fetch = #"<fetch mapping='logical' count='100' version='1.0'>
<entity name='annotation'>
<attribute name='filename' />
<attribute name='documentbody' />
<attribute name='mimetype' />
</entity>
</fetch>";
foreach (Entity e in service.RetrieveMultiple(new FetchExpression(fetch)))
{
if (!String.IsNullOrWhiteSpace(e.Attributes["documentbody"].ToString()))
{
byte[] data = Convert.FromBase64String(e.Attributes["documentbody"].ToString());
File.WriteAllBytes(filePath + e.Attributes["filename"].ToString(), data);
}
}
}

Answer 2

I believe your fetchXML query have the issue. I too faced the same issue but with images in SSRS reports. Images were not loaded properly/got corrupt.
I fixed the issue by updating the fetch XML query with distinct = false as in the below statement.
<fetch version="1.0" output-format="xml-platform" mapping="logical" distinct="false" >
.....
</fetch>