Category: Problems

Axis Object – Auto Interval Error in SSRS line charts

I faced this problem because the data series in my line chart doesn’t have any data when the vertical axis’s minimum, maximum, Interval and Interval type properties are all set to “Auto”.

Reading from the net it seems that this problem can also occur when your data has values of infinity such as when you use an expression to calculate the series data values and there is a division by 0 somewhere which produces infinity.

To solve this problem when there are no data values, I set the minimum value and the maximum value of the vertical axis using the following expression

For minimum value:  =IIf(Min(Fields!Value.Value) = Nothing, 0, “Auto”)

For maximum value: =IIf(Max(Fields!Value.Value) = Nothing, 100, “Auto”)

Basically, if there are no maximum or minimum values in the dataset, set some default values. This way SSRS won’t complain and the report will show with no error messages.

Default Values for parameters not working in SSRS with SharePoint integration

I faced this problem while trying to set default values to parameters in a report that resides within the SharePoint site.

It turned out that once a report is uploaded to SharePoint, the default values for parameters are maintained in the server, so subsequent changes to the default values will have no effect after saving or overwriting the report in the server.

To solve this, delete the report from the server and upload the report again. Quite stupid, but it works.

SSRS line chart gaps are not correct

For SSRS line charts to display gaps in the data correctly, the data must explicitly tells that for certain timestamps there are no data in those timestamp.

If there is a gap between timestamp A and timestamp B, the line chart will only display a gap if there are table rows for timestamps between A and B that contain empty or nil values. Otherwise, it will connect the lines instead of showing gaps.

Strategies to debug irreproducible bugs, or Heisenbugs

If the code in question involves concurrency, check if there is a potential for deadlocks which occurs infrequently and hard to track.

Check for other factors: network conditions, equipment quality, environment, bugs originated from OSes or third party libraries.

Add sufficient loggings to the code in case the bug appears again by detecting the bug’s behaviour, so that in the future if it appears again you will have something to track it.

Add a notification mechanism to notify you when the bug appears again, similar to previous point.

Forget about it for a while and work on other tasks, so that you can look at it from another angle later.

Have another person with fresh eyes to look at the code and give new ideas on what might cause it.

Pass many different inputs to the code with many edge cases to see if the bug can be reproduced, might be very time consuming and not effective, but can try.

If it doesn’t appear again and you have no idea how to reproduce it, maybe it’s okay to just ignore it for the time being.

 

This document already has a ‘ DocumentElement ‘ node

I faced this exception while trying to generate a xml document programmatically in C# using XmlDocument and XmlElement.

I didn’t know what was going on, and then I figured out that I was adding multiple elements to the XmlDocument. To solve this, add a “root” element to XmlDocument and then add multiple child elements within the root. The XmlDocument is supposed to only contain 1 child element as expected in XML.

Creating additional series from same table column for Line graphs in SSRS

I spent quite a lot of time experimenting to be able to do this.

Say you have a table like so

KPI        Value    Date

Temp      34        …

Press      12         …

 

And you would like to have 2 lines in the line graph, one for temperature, one for pressure, the series for pressure may use the secondary y axis. The series for pressure may use a totally different chart type(column).

To do this, don’t add KPI as a series group, add Date as a category group and add Value twice as values.

for the first Value, use IIf(Fields!KPI.Value = “Temp”, sum(Fields!Value.Value, Nothing).

for the second Value, use IIf(Fields!KPI.Value = “Temp”, sum(Fields!Value.Value, Nothing).

Configure the second value to use secondary y axis and you’re done.