Record Field Id

Can you provide some example of the data structure you have. If your field id in map is analog to record field's field id then index should work. Yet some more details will be better 

I have a grid with 30 Columns.
All these column names are stored in Table.

In the grid, used a!foreach to populate the headers.
For rows, a!foreach is used for each row generation. And for each column, again a!foreach is used. So here just with index, the values to be saved in the appropriate field.

In the picture, used an expression rule to return the recordtype!record.field based on the label.

Is there any way, we get the field index from table. Because we already have the Column Labels in table which is queried in the interface. If the field index is stored in table, we can use it easily. Considering the performance of displayvalue() when we have large set of columns, I am checking the possibility of taking it from the table.

Let's give it a try by doing this,

Update an Rule MCI_returnRecordFieldBasedOnLabel

a!localVariables(
  local!fieldMap: {
    {label: "Name", field: "name"},
    {label: "Description", field: "description"},
    {label: "Status", field: "status"},
    /* Add all 30 field mappings here */
  },

  index(
    index(
      local!fieldMap,
      wherecontains(ri!label, local!fieldMap.label),
      {}
    ),
    "field",
    null
  )
)

a!localVariables(
  local!columns: rule!getColumnsFromTable(), /* Your column labels from DB */
  local!data:{}, /* Your data */
{
  a!gridLayout(
    rows: a!forEach(
      items: local!data,
      expression: a!gridRowLayout(
        contents: a!forEach(
          items: local!columns,
          expression: a!textField(
            value: index(
              fv!item,
              rule!MCI_returnRecordFieldBasedOnLabel(
                label: fv!item.columnLabel
              ),
              null
            ),
            saveInto: {
              a!save(
                index(
                  fv!item,
                  rule!MCI_returnRecordFieldBasedOnLabel(
                    label: fv!item.columnLabel
                  ),
                  null
                ),
                save!value
              )
            }
          )
        )
      )
    )
  )
  }
)

Let's give it a try by doing this,

Update an Rule MCI_returnRecordFieldBasedOnLabel

a!localVariables(
  local!fieldMap: {
    {label: "Name", field: "name"},
    {label: "Description", field: "description"},
    {label: "Status", field: "status"},
    /* Add all 30 field mappings here */
  },

  index(
    index(
      local!fieldMap,
      wherecontains(ri!label, local!fieldMap.label),
      {}
    ),
    "field",
    null
  )
)

a!localVariables(
  local!columns: rule!getColumnsFromTable(), /* Your column labels from DB */
  local!data:{}, /* Your data */
{
  a!gridLayout(
    rows: a!forEach(
      items: local!data,
      expression: a!gridRowLayout(
        contents: a!forEach(
          items: local!columns,
          expression: a!textField(
            value: index(
              fv!item,
              rule!MCI_returnRecordFieldBasedOnLabel(
                label: fv!item.columnLabel
              ),
              null
            ),
            saveInto: {
              a!save(
                index(
                  fv!item,
                  rule!MCI_returnRecordFieldBasedOnLabel(
                    label: fv!item.columnLabel
                  ),
                  null
                ),
                save!value
              )
            }
          )
        )
      )
    )
  )
  }
)