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blog: note the one cell that cannot take a special missing

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2026-09-23 15:38:37 +00:00
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@@ -28,6 +28,8 @@ A display gotcha worth knowing: a regular missing prints as `.`, unless `options
In a SAS dataset they are written with a leading period (`.A`, `.B` ... `._`). In Data Controller you type just the letter or the underscore - no period - and the letter is not case sensitive. Two letters, or a letter mixed with a number, are refused rather than guessed. In a SAS dataset they are written with a leading period (`.A`, `.B` ... `._`). In Data Controller you type just the letter or the underscore - no period - and the letter is not case sensitive. Two letters, or a letter mixed with a number, are refused rather than guessed.
There is one cell where the letter cannot be typed at all. A numeric column that carries a date, datetime or time format is edited through a date picker rather than the numeric editor, and a picker accepts only a date.
## Carrying them between the browser and SAS ## Carrying them between the browser and SAS
The Data Controller frontend and the SAS backend exchange data as JSON, and JSON has no way to express a letter as a numeric value - `A` is a string. The conversion is handled in the open source [SASjs Adapter](https://github.com/sasjs/adapter#variable-types): The Data Controller frontend and the SAS backend exchange data as JSON, and JSON has no way to express a letter as a numeric value - `A` is a string. The conversion is handled in the open source [SASjs Adapter](https://github.com/sasjs/adapter#variable-types):
@@ -37,7 +39,7 @@ The Data Controller frontend and the SAS backend exchange data as JSON, and JSON
- Two cases cannot be inferred from the values alone: a numeric column containing *only* special missings looks like a single character column, and a character column containing only nulls looks numeric. For those, the adapter accepts an explicit format for the column - and Data Controller sends one automatically, because it already knows each column's SAS format from the metadata returned by the backend. - Two cases cannot be inferred from the values alone: a numeric column containing *only* special missings looks like a single character column, and a character column containing only nulls looks numeric. For those, the adapter accepts an explicit format for the column - and Data Controller sends one automatically, because it already knows each column's SAS format from the metadata returned by the backend.
- A value that is neither a number nor a single valid character is refused rather than guessed (for example `aaaa`, or `!` in a numeric column), and a literal `.` is refused in favour of `null` for a regular missing. - A value that is neither a number nor a single valid character is refused rather than guessed (for example `aaaa`, or `!` in a numeric column), and a literal `.` is refused in favour of `null` for a regular missing.
There is nothing to configure. Special missings are available by default, for numeric cells. There is nothing to configure. Special missings are available by default, for numeric cells - a date, datetime or time formatted column aside, since those edit through a date picker.
Once in SAS they are ordinary values, so they are what the approval DIFF screen compares, and the DIFF's formatted / unformatted switch shows either the formatted representation or the raw value - useful for confirming exactly which missing was set. Once in SAS they are ordinary values, so they are what the approval DIFF screen compares, and the DIFF's formatted / unformatted switch shows either the formatted representation or the raw value - useful for confirming exactly which missing was set.
@@ -90,6 +92,7 @@ We solved that in the open source SASjs Adapter, and it has been in Data Control
- the adapter infers the column type from the values, so a column of numbers that also holds a lone letter is written to SAS as numeric, with the letter as a special missing - the adapter infers the column type from the values, so a column of numbers that also holds a lone letter is written to SAS as numeric, with the letter as a special missing
- where the type cannot be inferred - a numeric column holding ONLY special missings - Data Controller passes the column format explicitly - where the type cannot be inferred - a numeric column holding ONLY special missings - Data Controller passes the column format explicitly
- you type the letter on its own: a or A, no period, and case does not matter - you type the letter on its own: a or A, no period, and case does not matter
- one exception: a date, datetime or time formatted numeric column edits through a date picker, which takes only a date
How they behave in Data Controller's validation rules: How they behave in Data Controller's validation rules: