How does sibling or siblingAtRow() function works to retrieve the value from hidden Column in QTableWidget?

Question

I have a database from which data is coming into a QTableWidget. The table in the database has the following Columns,

ID (Primary key, auto-increment value)
Name
Location

The QTableWidget has the following columns (that I have added)

ID (this column, I have hidden. and it contains the value of "ID" column from the Database Table)
Sr # (Represents the Row Number of the table)
Name (Contains "name" from the database table)
Location (Contains "Location from the database table)
Actions (Contains a Delete Button for that Row)

By hidden, I mean to say that I have made this column hidden using the folliwng command,

self.ui.table.setColumnHidden(0, True);

This is how I am populating my QTableWidget and creating a Delete Function,

    def get_data(self):
        mycursor = self.DB.cursor()
        Subquery = "select id, name, location "
        Subquery += " from tbl_person"
        mycursor.execute(Subquery)
        numcols = len(mycursor.fetchall()[0])
        mycursor.execute(Subquery)
        numrows = len(mycursor.fetchall())
        self.ui.table.setRowCount(numrows)
        self.ui.table.setColumnCount(numcols+2)
        mycursor.execute(Subquery)
        tablerow = 0
        for row in mycursor.fetchall():
            layout = QHBoxLayout()
            layout.setContentsMargins(0, 0, 0, 0)
            layout.setSpacing(0)
            delete_button = QPushButton("Delete Data")
            delete_button.clicked.connect(self.executeDeleteFunction)
            # delete_button.setStyleSheet(delete_push_button) -> Only for styling
            self.ui.table.setItem(tablerow, 0, PySide2.QtWidgets.QTableWidgetItem(str(row[0])))
            self.ui.table.setItem(tablerow, 1, PySide2.QtWidgets.QTableWidgetItem(str(tablerow+1)))
            self.ui.table.setItem(tablerow, 2, PySide2.QtWidgets.QTableWidgetItem(str(row[1])))
            self.ui.table.setItem(tablerow, 3, PySide2.QtWidgets.QTableWidgetItem(str(row[2])))
            self.ui.table.setCellWidget(tablerow, 4, delete_button)
            tablerow += 1
        self.ui.table.setColumnHidden(0, True)
        #self.ui.registered_table.horizontalHeader().setSectionResizeMode(PySide2.QtWidgets.QHeaderView.Stretch)
        self.ui.table.resizeColumnsToContents()

def executeDeleteFunction(self):
    self.person_id = self.ui.table.selectionModel().selectedIndexes()[0]
    self.person_id = self.person_id.row()
    mycursor = self.DB.cursor()
    sql = "delete from tbl_person where id = %s"
    val = (id, )
    mycursor.execute(sql, val)
    print("Deletion Successful")

On the Deletion Function, what this code does is basically gets the value of the **Sr # ** Column from the QTableWidget and deletes the data according to that, i.e. it is getting me the value from the visible first column and not the actual first column. But, I want the data from the "ID" column of the QTableWidget which is hidden

I tried to look up on how to get the value from the first hidden column on the QTableWidget and ended up with this link: How to get data from hidden 'id' column in QtableWidget

This apparently solves my issue but I can not seem to make it work for my code. I don't want to retrieve values of multiple Rows but only of one row so how do I do this (as I am only deleting one row. But in the question mentioned, I believe that it is getting data from multiple rows due to that for each loop)?

Moreover, I tried to find help regarding the functionality of sibling function (which is provided in the answer of above question) however I could not find any good resource on this function (i.e. how to use this, or some practical example and etc.)

I tried the following with Sibling function to obtain the value of first hidden column of the Selected Row but it did not work,

self.value = self.table.selectedItems()[0]
self.value = sibling(self.value.row(), 0)

Your question is a bit confusing. First of all, your query seems to be about an actual Qt item model, but your question and tags refer to QTableWidget, which has its own (slightly private and code-built) model. Also, you're talking about hidden columns, but then you say that you're getting multiple *rows*, which makes it even more confusing. If you're creating the QTableWidget *ignoring* the auto-increment column, you cannot get it in any way, unless you create a reference to that; practically speaking, if you just create the table layout ignoring the first column, you can *never* get it back. — musicamante, Dec 18 '21 at 00:18
So, I strongly urge you to [edit] your question, provide a [mre] and add more *clear* details about what you got, how you do it, and what you want to get. — musicamante, Dec 18 '21 at 00:20
@musicamante I have made amendments in the Question. My question is related to Qt Item model (however, since I am working on QTableWidget so that's why I added its tag). I am not getting multiple rows, I only need data from the `one selected row` however, the question I linked was getting data from multiple rows *(as far as of what I understood)*. I hope the question is a bit more understandable now. — Awais Shahid, Dec 18 '21 at 00:54

musicamante · Accepted Answer · 2021-12-18T19:11:39.730

1

There are some conceptual problems with the given code.

First of all, the QtSql module should be preferred instead of artificially creating a model. For basic tables, QSqlTableModel is fine enough, while for custom queries, QSqlQueryModel is a good choice.

Now the problem is that UI-based selection is always based on visible items: if you select a row in a view that has hidden columns, you will not get the hidden indexes that belong to those columns.

In order to get the indexes (as in QModelIndex) of hidden columns on a table widget, the only way is the same for a table view: you need to access the model and get the index for the row, or you get the actual model index and then get the sibling (which is conceptually the same, as the underlying function does):

    item = self.table.selectedItems()[0]
    index = self.table.indexForItem(index)
    firstRowIndex = index.sibling(index.row(), 0)
    sqlIndex = firstRowIndex.data() # might be a string

Note that you can also use siblingAtColumn():

    firstRowIndex = index.siblingAtColumn(0)

That's because when you create QTableWidget items, you're actually creating a new model, and the row for that model doesn't reflect the actual "row" of that index in the source model; items in the second row will return 1 for row(), even if their actual row is different, and that's because that item has been added as second to the table widget, since it's the second item in the query.

So, the solution is that you either get the incremental row value for the first column index sibling, or you use one of the predefined Sql models.

For simple models, the latter solution is fine enough, but if you need more complex models, the first is certainly more accurate and reliable.

edited Dec 18 '21 at 19:11

answered Dec 18 '21 at 01:55

musicamante

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Ok, I understand somewhat you have said. Thank you for providing a detailed answer. Unfortunately, it wouldn't be possible for me to convert to QSqlTableModel now because I have already made quite a huge project which have around 6-7 QTableWidgets and they all will need to be changed. However, fortunately, my other column values (when combined) are unique and so, I am now using those to retrieve/update data in the Database (i.e. by using value of both Name + Location, not the efficient way but it is a good work around) – Awais Shahid Dec 18 '21 at 17:52
I just have one more question if you are free and can answer it. I found this Post on a very similar issue to mine: https://stackoverflow.com/a/56799063/11454905 According to this post, you can actually Hide/Show the First Column and retrieve its Value. Can you tell me if that is possible? I tried to do the same however it did not work (the self.ui.table.selectedModel.selectedIndexes()[0] still gave me the ID of 2nd Column (i.e. the first visible column))... Or maybe it worked for them because they are using QSqlQueryModel? – Awais Shahid Dec 18 '21 at 17:54
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@TalhaAyub Frankly, I find that question confusing (the OP is hiding the row, but they're talking about the column) and the answer terrible and unreliable: showing and hiding rows or columns can possibly cause a complete computation of *all* geometries (headers, items, etc), requesting a lot of data to the model, and repainting the whole widget, and if the selection behavior isn't set for `SelectRows` it wouldn't update the selection. Using the approach I gave you is more reliable, faster and consistent. I strongly suggest you to consider switching to QSqlTableModel, because at some point -> – musicamante Dec 18 '21 at 19:09
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@TalhaAyub you'll probably find yourself overcomplicating your code because you have to keep updating the database programmatically. It's even possible that some day you will need to switch anyway, for that reason, and that day the amount of work required to do it will be much, much bigger. – musicamante Dec 18 '21 at 19:11
Absolutely, its getting a bit complicated to retrieve unique rows for all the tables as well using the columns other than the ID. Thanks a lot for your time, I guess I will have to go with the complete change of the tables. Thank you! – Awais Shahid Dec 19 '21 at 01:36

How does sibling or siblingAtRow() function works to retrieve the value from hidden Column in QTableWidget?

1 Answers1