Isempty
isempty
checks if a value in a string column is an empty string (""
).
In Metabase, you must combine isempty
with another expression that accepts boolean values. The table below shows you examples of the boolean output that will be passed to your other expression(s).
Syntax | Example with an empty string | Example with a true null |
---|---|---|
isempty(value) |
isempty("") |
isempty(null) |
Returns true if the value is an empty string, false otherwise. |
true |
false |
How Metabase handles empty strings
In Metabase, columns with string data types will display blank cells for empty strings or null
values (if the column is nullable in your database).
For example, in the column below, the empty cells could contain either:
""
: feedback was submitted and left intentionally blank, so the person had “no feedback to give”.null
: no feedback was submitted, so the person’s thoughts are “unknown”.
Feedback |
---|
I like your style. |
Replacing empty strings with another value
Feedback | case(isempty([Feedback]), "No feedback.", [Feedback]) |
---|---|
No feedback. | |
I like your style. | I like your style. |
Combine isempty
with the case
expression to replace empty strings with something more descriptive.
Let’s say that the second row’s blank cell is actually an empty string, so isempty
will return true
. The case
statement evaluates true
to return the first output “No feedback”.
The first row’s blank cell doesn’t have an empty string, but because it’s blank, we’re not sure what’s in it either—it could be a null
, or even an emoji that blends into your table background. No matter what the edge case is, isempty
will return false
, and case
will return whatever’s in the Feedback column as the default output.
Accepted data types
Data type | Works with isempty |
---|---|
String | ✅ |
Number | ❌ |
Timestamp | ❌ |
Boolean | ❌ |
JSON | ❌ |
Limitations
- In Metabase, you must combine
isempty
with another expression that accepts boolean arguments (i.e.,true
orfalse
). isempty
only accepts one value at a time. If you need to deal with empty strings from multiple columns, you’ll need to use multipleisempty
expressions with the case expression.- If
isempty
doesn’t seem to do anything to your blank cells, you might havenull
values. Try theisnull
expression instead.
Related functions
This section covers functions and formulas that can be used interchangeably with the Metabase isempty
expression, with notes on how to choose the best option for your use case.
All examples below use the table from the Replacing empty strings example:
Feedback | case(isempty([Feedback]), "No feedback.", [Feedback]) |
---|---|
No feedback. | |
I like your style. | I like your style. |
SQL
In most cases (unless you’re using a NoSQL database), questions created from the notebook editor are converted into SQL queries that run against your database or data warehouse.
CASE WHEN Feedback = "" THEN "No feedback"
ELSE Feedback END
is equivalent to the Metabase isempty
expression:
case(isempty([Feedback]), "No feedback.", [Feedback])
Spreadsheets
If our sample feedback column is in a spreadsheet where “Feedback” is in column A, then the formula
=IF(A2 = "", "Unknown feedback.", A2)
is equivalent to the Metabase isempty
expression:
case(isempty([Feedback]), "No feedback.", [Feedback])
Python
Assuming the sample feedback column is in a dataframe column called df["Feedback"]
:
df["Custom Column"] = np.where(df["Feedback"] == "", "No feedback.", df["Feedback"])
is equivalent to the Metabase isempty
expression:
case(isempty([Feedback]), "No feedback.", [Feedback])