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  4. Conversion of a SQL model into a standard item model?

Conversion of a SQL model into a standard item model?

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qsqltablemodelqstandarditemmodata modelsproxiessoftware design
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  • E elfring
    22 Oct 2018, 13:52

    May I ask why?

    • Possible change resistance
    • Unclear development efforts (and additional dependencies) for a software transformation to better SQL data models
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    VRonin
    wrote on 22 Oct 2018, 13:58 last edited by
    #4

    @elfring said in Conversion of a SQL model into a standard item model?:

    Possible change resistance

    Deal with it.
    If you mean change in code, by only interacting with QStandardItemModel via the QAbstractItemModel interface as I always suggest, makes changing the model a matter of 1 code line

    Unclear development efforts (and additional dependencies)

    The additional dependency is the SQL module. Hard to get around it if you want to interact with an SQL database

    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
    ~Napoleon Bonaparte

    On a crusade to banish setIndexWidget() from the holy land of Qt

    E 1 Reply Last reply 22 Oct 2018, 14:07
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    • V VRonin
      22 Oct 2018, 13:58

      @elfring said in Conversion of a SQL model into a standard item model?:

      Possible change resistance

      Deal with it.
      If you mean change in code, by only interacting with QStandardItemModel via the QAbstractItemModel interface as I always suggest, makes changing the model a matter of 1 code line

      Unclear development efforts (and additional dependencies)

      The additional dependency is the SQL module. Hard to get around it if you want to interact with an SQL database

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      elfring
      wrote on 22 Oct 2018, 14:07 last edited by
      #5

      … if you want to interact with an SQL database

      Unfortunately, the Qt software documentation mentions specific limitations for the class “QSqlTableModel” so far.

      1 Reply Last reply
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        SGaist
        Lifetime Qt Champion
        wrote on 22 Oct 2018, 14:10 last edited by
        #6

        Do you mean the ones solved by QSqlRelationalTableModel and QSqlRelationalDelegate mentioned in the documentation you are linking to ?

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

        E 1 Reply Last reply 22 Oct 2018, 14:18
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        • S SGaist
          22 Oct 2018, 14:10

          Do you mean the ones solved by QSqlRelationalTableModel and QSqlRelationalDelegate mentioned in the documentation you are linking to ?

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          elfring
          wrote on 22 Oct 2018, 14:18 last edited by
          #7

          Maybe.

          Do both table model classes share still the main restriction on editing from a single database table?

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            SGaist
            Lifetime Qt Champion
            wrote on 22 Oct 2018, 14:23 last edited by
            #8

            It's not a restriction, it's how the class works. QSqlTableModel as it name suggest allows access to one table.

            So what exactly are you after ?
            Specify a real situation
            Specify a real need

            Interested in AI ? www.idiap.ch
            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

            E 1 Reply Last reply 22 Oct 2018, 14:28
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            • S SGaist
              22 Oct 2018, 14:23

              It's not a restriction, it's how the class works. QSqlTableModel as it name suggest allows access to one table.

              So what exactly are you after ?
              Specify a real situation
              Specify a real need

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              elfring
              wrote on 22 Oct 2018, 14:28 last edited by
              #9

              QSqlTableModel as it name suggest allows access to one table.

              Can such classes collaborate also with database views?

              V 1 Reply Last reply 22 Oct 2018, 14:37
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              • E elfring
                22 Oct 2018, 14:28

                QSqlTableModel as it name suggest allows access to one table.

                Can such classes collaborate also with database views?

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                VRonin
                wrote on 22 Oct 2018, 14:37 last edited by
                #10

                From the article you linked:

                If the database system can determine the reverse mapping from the view schema to the schema of the underlying base tables, then the view is updatable. INSERT, UPDATE, and DELETE operations can be performed on updatable views.

                Since there's no generic way for a Qt model to know that, it is left to the user to implement using QSqlQuery directly

                "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                ~Napoleon Bonaparte

                On a crusade to banish setIndexWidget() from the holy land of Qt

                E 1 Reply Last reply 22 Oct 2018, 14:44
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                • V VRonin
                  22 Oct 2018, 14:37

                  From the article you linked:

                  If the database system can determine the reverse mapping from the view schema to the schema of the underlying base tables, then the view is updatable. INSERT, UPDATE, and DELETE operations can be performed on updatable views.

                  Since there's no generic way for a Qt model to know that, it is left to the user to implement using QSqlQuery directly

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                  elfring
                  wrote on 22 Oct 2018, 14:44 last edited by
                  #11

                  Would it be nicer if a table model can determine if it is based on an updatable view?

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                  • V Offline
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                    VRonin
                    wrote on 22 Oct 2018, 15:09 last edited by VRonin
                    #12

                    Yes, but once again

                    @VRonin said in Conversion of a SQL model into a standard item model?:

                    there's no generic way for a Qt model to know that

                    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                    ~Napoleon Bonaparte

                    On a crusade to banish setIndexWidget() from the holy land of Qt

                    E 1 Reply Last reply 22 Oct 2018, 15:39
                    1
                    • V VRonin
                      22 Oct 2018, 15:09

                      Yes, but once again

                      @VRonin said in Conversion of a SQL model into a standard item model?:

                      there's no generic way for a Qt model to know that

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                      elfring
                      wrote on 22 Oct 2018, 15:39 last edited by
                      #13

                      Do full-featured standard item models become a bit more attractive then?

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                        SGaist
                        Lifetime Qt Champion
                        wrote on 22 Oct 2018, 19:06 last edited by
                        #14

                        Attractive for what ?

                        Interested in AI ? www.idiap.ch
                        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                        E 1 Reply Last reply 28 Oct 2018, 13:10
                        1
                        • S SGaist
                          22 Oct 2018, 19:06

                          Attractive for what ?

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                          elfring
                          wrote on 28 Oct 2018, 13:10 last edited by
                          #15

                          Would you like to compare the attractiveness of the mentioned data model variants any further?

                          1 Reply Last reply
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                            SGaist
                            Lifetime Qt Champion
                            wrote on 28 Oct 2018, 21:45 last edited by
                            #16

                            I'll let you start by providing the analysis you want to discuss about.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            E 1 Reply Last reply 29 Oct 2018, 08:49
                            3
                            • S SGaist
                              28 Oct 2018, 21:45

                              I'll let you start by providing the analysis you want to discuss about.

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                              elfring
                              wrote on 29 Oct 2018, 08:49 last edited by
                              #17

                              Is there a “development competition” going on between data processing by SQL queries and/or Qt standard items?

                              J 1 Reply Last reply 29 Oct 2018, 09:17
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                              • E elfring
                                29 Oct 2018, 08:49

                                Is there a “development competition” going on between data processing by SQL queries and/or Qt standard items?

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                                JKSH
                                Moderators
                                wrote on 29 Oct 2018, 09:17 last edited by JKSH
                                #18

                                @elfring said in Conversion of a SQL model into a standard item model?:

                                Is there a “development competition” going on between data processing by SQL queries and/or Qt standard items?

                                No, there is no competition going on.

                                @elfring, what is your goal for asking us these questions? Are you trying to get us to write a "software extension" for you?

                                Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

                                E 1 Reply Last reply 29 Oct 2018, 09:57
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                                • J JKSH
                                  29 Oct 2018, 09:17

                                  @elfring said in Conversion of a SQL model into a standard item model?:

                                  Is there a “development competition” going on between data processing by SQL queries and/or Qt standard items?

                                  No, there is no competition going on.

                                  @elfring, what is your goal for asking us these questions? Are you trying to get us to write a "software extension" for you?

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                                  elfring
                                  wrote on 29 Oct 2018, 09:57 last edited by
                                  #19

                                  I hope that more software evolution can happen in this area so that the switching between discussed data models might become easier.

                                  J 1 Reply Last reply 29 Oct 2018, 23:44
                                  0
                                  • E elfring
                                    29 Oct 2018, 09:57

                                    I hope that more software evolution can happen in this area so that the switching between discussed data models might become easier.

                                    J Offline
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                                    JKSH
                                    Moderators
                                    wrote on 29 Oct 2018, 23:44 last edited by JKSH
                                    #20

                                    @elfring said in Conversion of a SQL model into a standard item model?:

                                    I hope that more software evolution can happen in this area so that the switching between discussed data models might become easier.

                                    We will not perform this "software evolution" because we cannot see any good reason to provide additional conversion/switching between QSqlTableModel and QStandardItemModel. Furthermore, none of your posts above provide convincing arguments for this conversion/switching.

                                    Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

                                    E 1 Reply Last reply 30 Oct 2018, 08:17
                                    3
                                    • J JKSH
                                      29 Oct 2018, 23:44

                                      @elfring said in Conversion of a SQL model into a standard item model?:

                                      I hope that more software evolution can happen in this area so that the switching between discussed data models might become easier.

                                      We will not perform this "software evolution" because we cannot see any good reason to provide additional conversion/switching between QSqlTableModel and QStandardItemModel. Furthermore, none of your posts above provide convincing arguments for this conversion/switching.

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                                      elfring
                                      wrote on 30 Oct 2018, 08:17 last edited by
                                      #21

                                      Will other Qt users share more convincing arguments from involved software development challenges?

                                      J J 2 Replies Last reply 30 Oct 2018, 08:21
                                      0
                                      • E elfring
                                        30 Oct 2018, 08:17

                                        Will other Qt users share more convincing arguments from involved software development challenges?

                                        J Offline
                                        J Offline
                                        JonB
                                        wrote on 30 Oct 2018, 08:21 last edited by
                                        #22

                                        @elfring

                                        Will other Qt users share more convincing arguments from involved software development challenges?

                                        "Other Qt users" will not even understand what these unending questions are about ;-) Just saying....

                                        E 1 Reply Last reply 30 Oct 2018, 08:24
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                                        • J JonB
                                          30 Oct 2018, 08:21

                                          @elfring

                                          Will other Qt users share more convincing arguments from involved software development challenges?

                                          "Other Qt users" will not even understand what these unending questions are about ;-) Just saying....

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                                          elfring
                                          wrote on 30 Oct 2018, 08:24 last edited by
                                          #23

                                          I assume that some Qt users will care for collateral evolution around data models.

                                          1 Reply Last reply
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