Dropdown node does not show query result when it is a array[1]

[QGIO]

Hello forum,

I have a problem with the drop down node.
I make a query by SQL node to a Database table and I get the desired result. This result is then linked to a dropdown node, but I have a problem just in one case.
When the result of my query is an array with just one object like this:

in the dropdown list I don't see the result, like this:

while if the array contains more objects I don't have problem and see the list (result of my query).
The query works fine, the problem is in the shown dropdown list.

I pass data do the dropdown node in this way:

Do you have an idea of the origin of this problem?

Many thanks

[Steve-Mcl]

Put a debug node after the change node (set to show complete message) - what do you see?

Then, compare your data to the example in the built in help of the drop down node, does your options match the required format?

[QGIO]

Here it is the debug node result of change node

I see the array is not empty, but I don't see in the UI dropdown list

[QGIO]

I followed this link

UI Dropdown - get result from SQL

Have some data from a MSSQL node that I want to insert as values in a Dropdown node, so I can return the selected value. But have searched high and low, but have not found and examble I can use Data… [{“Name”:“Name1”},{“Name”:“Name2”},{“Name”:“Name3”},{“Name”:“Name4”},{“Name”:“Name5”},{“Name”:“Name6”},{“Name”:“Name7”},{“Name”:“Name8”}]

[Steve-Mcl]

You did not set debug node to show complete message. I cannot see msg.options so you can't have compared it to the built in help.

[shrickus]

When you use this JSONata expression:

$.payload.ID_Scad

it returns an array of values ONLY if there are more than one IDs found in the payload array. Otherwise it is flattened to a single value (as you found out the hard way). I'm guessing that the dropdown node is always expecting an array of values, instead of a single string, which is why it's blank.

To force your expression to always return an array, try appending square brackets like this...
(I removed the leading $. since it does nothing):

payload.ID_Scad[]

This causes any matching output to be returned as an array, so 1 or more values -- if nothing is matched, then nothing is returned.

The other syntax you can use is to wrap the entire expression in square brackets:

[payload.ID_Scad]

so even if nothing is found, you will get back an empty array -- FYI

[Steve-Mcl]

@QGIO

but it doesn't work, when I have just one object I don't see it in the dropdown.

As i said twice...

@Steve-Mcl

Put a debug node after the change node (set to show complete message)

This will let us see what you are sending in msg.options to the drop down node.

[QGIO]

[Steve-Mcl]

And there is the problem - it is not an array.

JSONata expression payload.ID_Scad[] in change node should work.

If not, then a function node equivalent would be

msg.payload = msg.payload.map(e => e.ID_Scad);
return msg;