Referencing of form variables within a "Valid If" expression

Suppose I have a table,

TableA(Column1, Column2)

In the Column1’s “Valid if - EXPRESSION ASSISTANT”, the [_THIS] refer to the Column1’s value shown on TableA’s forms (Add or Edit). How can I refer/use the Column2’s form value in the Column1’s EXPRESSION ASSISTANT?

Regards,

Hi @Swoopy,

If I clearly understand your requirement, if you wish to use value from Column2 in the valid if of Column1 , please use an expression something like [Column2]= “Great” or [Column2]>10

In short mention column2 name and a value for that column that makes Column1 valid.

Please let us know if you are looking for something else.

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Thank you. I’m too newbie in this environment :slight_smile:

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Hi @Swoopy,
No problem. We are all beginners in the initial stages for any new thing. Please do ask your questions anytime. AppSheet community is a great community.

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captured1

My table has a column Void containing texts (“No” and “Void”). I tested its value using ISNOTBLANK([_THISROW].[Void]) in Valid If of column Quantity. When open Edit form of this table, it shows “This entry is invalid” (which means it’s blank), why?

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Remove [_THISROW]. from the expression.

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My understanding of AppSheet environment is that the [Void] alone (without [_THISROW]) in Valid If refers to the value of Void field on the Edit form. I need to refer the Void value in the table I am about to edit its row.

Your understanding is incorrect.

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I re-tested the [Void] alone without “[_THISROW].”

If the Edit form is just open, [Void] value is equal to the Void of that row saved in table.

If I change the Void field on Edit form, [Void] keeps the new value on-the-fly.

However, I have a situation that my condition requires to compare the old value of Void previously saved in table -with- the Void value selected by user on Edit form. But I don’t know how to refer to the table’s void value if user changes the void field.

Regards,

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If you need to be able to use the previous value entered by a user, you’ll need some way to store that variable separately from the main data-entry field; this way you have two fields in which you can compare them against each other and do logic functions.

You’ll also need another field to be the “display” field - that watches the “change” field and if it’s empty it copies the original value, if it’s changed it copies the new value. This gives you a single field in which to display to users. Unless you wish to show the original and the change, etc… you can see there’s a lot here. :slight_smile:


Alternatively, if you just need to trigger a workflow if someone has changed a value from the original, there’s a way to reference the previous value of a form in logic:



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Functions that do table lookups, like FILTER(), LOOKUP(), and SELECT(), actually reference the table, not the copy of the row in the editor. Try this to get the saved copy:

LOOKUP(
  [_THISROW].[key-column],
  "table-name",
  "key-column",
  "Void"
)

replacing table-name with the name of the table and key-column with the name of the table’s key column. Note that [_THISROW]. is required in the above.

You can then wrap this LOOKUP() expression in ISNOTBLANK() in your Valid If expression.

See also:

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Thank you so much. Now I’am able to carry on my learning project.

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