🚑 🆘 [FirstAid] Handling of The source contains no DataRows exception

This FirstAid Tutorial will describe how a the source contains no DataRows EXCEPTION can be handled.

Introduction

Let’s have a look at the following filter data table scenario:

Name CCode
Tom US
Charlotte FR
Seema IN
Jean FR

Assignment:

  • Filter all rows on a particular Country Code like FR, UK, ES, UK…
  • Ensure that all CCode data column values are trimmed
  • Ensure that the Filter check is case insensitive

we can implement it e.g. with the help of a LINQ statement:

dtData.AsEnumerable.Where(Function (x) x("CCode").toString.Trim.ToUpper.Equals(strCCFilter.ToUpper)).CopyToDataTable
Visuals

Result and Exception

Success

When the data table will be filtered for “fr” the following result will be received:
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Failure

When the data table will be filtered for “uk” a the source contains no DataRows EXCEPTION will be thrown
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Reason: when the filter result will be empty, there are no rows for copying it to the resulting data table.

Defensive Handling

Strategy

The main idea for defensive handling is about collecting all filtered rows to a list. Depending on the list count the CopyToDataTable method will be called or the original data table will be cloned

Fixing Actions - LINQ

Variables

For the pre-step result, a variable Result of the datatype: List(of DataRow) will be created
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Details

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then click OK, OK

LINQ Statement & Assign Change

instead of CopyToDatatable a ToList will be used
The return of the LINQ will be assigned to the Variable: Result
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Defensive Check Block

Within an IF Activity following will be modeled:

Condition: Result.Count > 0
Then Branch: dtResult = Result.CopyToDataTable
Else Branch: dtResult = dtData.Clone

dtData is the origin datatable. With the Clone Method an empty data table with the same data column structure of dtData will be created and assigned to dtResult

Visual

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Fixing Actions - DataTable.Select Method

Similar to the above-described steps (Fixing Actions - LINQ) a defensive handling can also be
implemented for the DataTable.Select Method approach:

Variables

For the pre-step result, a variable Result of the datatype: List(of DataRow) will be created
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Details

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then click OK, OK

Assignment

Result = dtData.Select("..YourSelectFilterExpression..").ToList()

Defensive Check Block

Within an IF Activity following will be modeled:

Condition: Result.Count > 0
Then Branch: dtResult = Result.CopyToDataTable
Else Branch: dtResult = dtData.Clone
Visual

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dtData is the origin datatable. With the Clone Method an empty data table with the same data column structure of dtData will be created and assigned to dtResult

Conclusion

with the implementation of the above an empty filter result can be handled defensively and a the source contains no DataRows EXCEPTION can be avoided.

Downloads

Find starter help here:
ppr_FirstAid_NoSourceRows.xaml (8.4 KB)

References

The first aid series offers various instructions on how to tackle a difficulty with the first steps

Questions

For questions on your specific case open a new topic and get individual support

15 Likes

A post that was very much needed in this community, thank you for taking the time to write this for us, we appreciate it!

Kind Regards,
Ashwin A.K

1 Like

Great post @ppr! Just wanted to add that you can also merge it all in one expression if you don’t want to use several activities.

(From i In {0}
	Let matchingRows = dtData.AsEnumerable.Where(Function (x) x("CCode").toString.Trim.ToUpper.Equals(strCCFilter.ToUpper))
	Select If (matchingRows.Count > 0, matchingRows.CopyToDataTable, dtData.Clone)
).First

image

5 Likes

Hi Peter!
Thank you for this post. I was really looking for something like that!
Cheers,

This was cool, But in my scenario in filtering datatable, if i had 2 rows, and those 2 are filtered and my datatable is beoming blank, how to handle this scenario ,

I am deleliting all filtered data, so my filterdatatable is trowing error.

If you use my LINQ-expression you should have a an empty data table (with correct headers but no rows.) That is was the dtData.Clone does.

How do you filter your datatable? Could you show us your LINQ-expression?

@MitheshBolla @ptrobot

we would recommend to open a new topic for this discussion

2 Likes