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NULL Value Specs

Context

A NULL value indicates that a value does not exist in a database. It is important to clarify that NULL is not the same as blank or zero. Ideally, we want users to think of NULL values as placeholders for unknown or missing values applicable otherwise.

Prototype

Prototype

Videos

User Experience

Considerations for handling NULL Values

When presented in tables, NULL values should be visually distinct so that the user understands that they are not the same as other string types. The style should attempt to communicate the absence of a value, similar to how placeholders are used in text input fields. As for the process of transforming values to and from NULL, it will be important to have a consistent way of doing this across different data types.

Scenarios

Scenario 1: User identifies a NULL Value

Scenario 1a: The user identifies a NULL value in a table

Steps for 1a
  1. The user opens a table that contains NULL values.
  2. The user identifies a cell that contains a NULL value.
    • The cell contains the word NULL in all uppercase letters
    • The cell has a different styling
      • A lighter background-color
      • A muted text color
      • A different font style (italic)

Scenario 1b: The user identifies a NULL value in a record preview

Steps for 1b
  1. The user edits a value in a column that links to records from another table.
  2. The user sees the list of records displayed in the record selection dropdown.
  3. The user identifies a record that contains a NULL value.
    • The field contains the word NULL in all uppercase letters
    • The text has a muted text color
    • The text has a different font style (italic)

Scenario 1c: The user identifies a NULL value in a boolean type column in checkbox display mode

Steps for 1c
  1. The user opens a table that contains NULL values.
  2. The user identifies a cell that contains an indeterminate state checkbox.
  3. The user hovers over the indeterminate checkbox, and a tooltip with the legend NULL is displayed.

Scenario 2: User edits a NULL Value

Scenario 2a: Replacing NULL with a new value

Steps for 2a
  1. The user edits a NULL value in a column.
  2. The user enters edit mode.
  3. The user enters a new value and leaves edit mode by pressing the enter key or clicking outside the active cell.
  4. The new value replaces the NULL value.

Scenario 2b: Replacing NULL with an empty string

Steps for 2b
  1. The user edits a NULL value in a column.
  2. The user enters edit mode.
  3. A text input box is displayed in edit mode with a placeholder set to NULL.
  4. The new typed-in value replaces the placeholder text.
  5. The user clears the new value by pressing the backspace key until the value is completely cleared.
  6. The user leaves edit mode.
  7. An empty string replaces the NULL value. The cell appears blank.

Scenario 2c: The data type is boolean with checkbox display mode enabled

Steps for 2c
  1. The user edits a NULL value in a column set to boolean type with the checkbox display mode enabled.
    • The field contains a checkbox in an indeterminate state, meaning the value is NULL.
  2. The user clicks on the checkbox, going from indeterminate NULL to checked TRUE.
  3. The user can click on the checkbox again to mark it as FALSE.
  4. To return the value to NULL, the user can select the cell and press the delete key or use the contextual menu and select the Set as NULL option.

Scenario 2d: The data type is number

Steps for 2d
  1. The user edits a NULL value in a column set to number type.
  2. The user double-clicks the cell to enter `edit mode.
  3. The user leaves edit mode without making any changes.
  4. The NULL value remains unchanged.

Scenario 3: User sets a value to NULL

Scenario 3a: The column accepts NULL values

Steps for 3a
  1. The user selects a cell in a column that contains a value.
  2. The user clears the content of the selected cell.
    • By pressing the Shift+Backspace or Shift+Delete keys.
    • By opening the contextual menu and selecting the Set as NULL option.
  3. The selected cell now has a NULL value.

Scenario 3b: The column does not accept NULL values

Steps for 3b
  1. The user selects a cell in a column that contains a value.
  2. The user attempts to clear the content of the selected cell.
    • By pressing the Shift+Backspace or Shift+Delete keys.
      • The system prevents the insertion of a NULL value.
      • An error message indicates that a NOT NULL constraint is applied to the column, and the system cannot insert NULL values.
    • By opening the contextual menu and selecting the Set as NULL option.
      • The ‘Set as NULL’ option is disabled, and the user cannot select it.

Interactions

Select vs. Edit Mode Behaviors

In Select Mode, the cell is highlighted and set as the target for actions applying to the cell or elements associated with it, such as its row or column. Select Mode is toggled by clicking on a cell or by navigating to with the direction keys while Select Mode is active.

In Edit Mode, a cell provides additional functionality and interactions to users. Edit Mode is toggled by double-clicking on a cell or by typing a text character or pressing backspace while in Select Mode. However, certain data types could have different interactions. Once specific behaviors and components for each data type are introduced, we must further define these interactions to ensure compatibility.

We will create an additional issue to refine these interactions.

Text or Numeric Types

For the implementation of this spec, we should consider the following interactions for the editing of text and numeric types as summarized in the following table:

current mode DOM key result
select any text character switch to edit mode, place cursor at end, append a character to end of cell contents
select Backspace switch to edit mode, place cursor at end, delete the last character
select Delete nothing
select Shift+Backspace set cell value to NULL
select Shift+Delete set cell value to NULL
edit Backspace delete a character to the left of cursor
edit Delete delete a character to the right of cursor

Boolean Type

In the case of boolean types, consider the following:

  • Consider that the checkbox is smaller than the cell, so clicking outside the checkbox would select the cell, and pressing delete would make the cell NULL.
  • Clicking inside the checkbox would toggle the value of the checkbox, similar to spreadsheets.

With Dropdown Enabled

Some column configurations will display a dropdown when editing the contents of a cell. For example, a column with a single-column foreign key constraint will show a record selector dropdown when in edit mode.

In the case of cells with dropdown enabled, consider the following:

  • If no record is selected, the cell content should be NULL.
  • To set the cell’s content as NULL, the user can press the delete key while the cell is in select mode.
  • To set the cell’s content as NULL, the user can deselect a selected record from the record selector by clicking on a selected item and then closing the dropdown.