How to catch data source error when up stream is missing

[JianliangJiang]

Hi Power BI experts,

My scenario is to get data from Azure blob, and the Azure blob may be missing for some data by design. I plan to make use of try-catch plus if to handle this. However, below query is always stuck.  Can anyone help point the correct way to 

Query

let
TargetDate = DateTimeZone.FromText("2019-03-19T01:30:00"),
MetricsName = "/Mock/"& DateTimeZone.ToText(TargetDate, "yyyy/MM/dd") & "/Metrics." & DateTimeZone.ToText(TargetDate, "yyyy_MM_dd") & ".tsv",
Source = AzureStorage.BlobContents("https://xxxxxxxxxxxxxx.blob.core.windows.net/yyyyyyyyyy" & MetricsName),
TestForError = try Source,
#"Imported CSV" =

if TestForError[HasError]

then #table({"Column1", "Column2" }, null)

otherwise Csv.Document(Source,[Delimiter="#(tab)", Columns=6, Encoding=1252, QuoteStyle=QuoteStyle.None]),

in
#"Imported CSV"

Screenshot FYI

[JianliangJiang]

Hi,

I succeeded working around the issue by filtering AzureStorage.Blobs result and checking its emptyness or not.

[d_gosbell]

I have not tested this, but I think you might just need to put the try in front of the call to AzureBlogStorage.BlobContents rather than storing that in the Source variable.

eg.

let
TargetDate = DateTimeZone.FromText("2019-03-19T01:30:00"),
MetricsName = "/Mock/"& DateTimeZone.ToText(TargetDate, "yyyy/MM/dd") & "/Metrics." & DateTimeZone.ToText(TargetDate, "yyyy_MM_dd") & ".tsv",
TestForError = try AzureStorage.BlobContents("https://xxxxxxxxxxxxxx.blob.core.windows.net/yyyyyyyyyy" & MetricsName),,
#"Imported CSV" =

if TestForError[HasError]

then #table({"Column1", "Column2" }, null)

otherwise Csv.Document(Source,[Delimiter="#(tab)", Columns=6, Encoding=1252, QuoteStyle=QuoteStyle.None]),

in
#"Imported CSV"

[JianliangJiang]

Thanks @d_gosbell.

The approach failed with the same behavior.