Null is converted to empty string when writing to database.

An easy workaround to query entities with empty ( null ) text fields is to use the following query filter:

a!queryFilter(
    field: "name",
    operator: "in",
    value: {"", null}
)

Thanks Philip. For some reason this didn't work for me when comparing to null, but it pointed me in the right direction. I ended up using the "queryLogicalExpression" function to do something like this:

a!queryLogicalExpression(
  operator: "OR",
  filters: {
    a!queryFilter(
      field: "name",
      operator: "is null"
    ),
    a!queryFilter(
      field: "name",
      operator: "in",
      value: {""}
    )
  }
)

Thanks Philip. For some reason this didn't work for me when comparing to null, but it pointed me in the right direction. I ended up using the "queryLogicalExpression" function to do something like this:

a!queryLogicalExpression(
  operator: "OR",
  filters: {
    a!queryFilter(
      field: "name",
      operator: "is null"
    ),
    a!queryFilter(
      field: "name",
      operator: "in",
      value: {""}
    )
  }
)