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| | == Description == | | == Description == |
| | | | |
| − | The task element is described in the [[Task_Management_Method#Task|"Task Management Method"]]. The tasks in the project are stored in a table in the project database. The name of a task does not have to be unique. Therefore, a task also has to have a unique id. Further, since a task represents a graphical element, it has a position, a width and a height. These attributes are expressed in pixels. The TaskDepender™ program uses a true-type font, and therefore the width and height will be determined when the task is displayed. | + | The task element is described in the [[Task_Management_Method#Task|"Task Management Method"]]. The tasks in the project are stored in a table in the project database. The name of a task does not have to be unique, a task has to have a unique id which can be generated as a integer primary key<ref name="primary_key">[http://www.sqlite.org/lang_createtable.html#rowid rowid - SQLite specification]</ref> by the database. Since a task represents a graphical element, it has a position, a width and a height. The TaskDepender™ program uses a true-type font, and therefore the width and height will be determined when the task is displayed. |
| | + | |
| | + | == Constraints == |
| | | | |
| | The following constraints apply for the tasks table: | | The following constraints apply for the tasks table: |
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| | | | |
| | == Design == | | == Design == |
| − |
| |
| − | === Columns ===
| |
| | | | |
| | The tasks are stored in a table with the following columns: | | The tasks are stored in a table with the following columns: |
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| | |} | | |} |
| | | | |
| − | === Constraints ===
| |
| − |
| |
| − | The two constraints for the table can be implemented by by [http://www.sqlite.org/foreignkeys.html#fk_actions referencing] these columns to the appropriate columns. This is done as follows:
| |
| − | * Delete contained task when container is deleted: self-reference the <tt>ContainerId</tt> column to the <tt>Id</tt> column.
| |
| − | * Set <tt>RecourceId</tt> to <tt>NULL</tt> when recource deleted: reference <tt>RecourceId</tt> to the <tt>Id</tt> in the [[Resources database table|resources table]].
| |
| − |
| |
| − | === Create ===
| |
| − |
| |
| − | When a new project is created, the tasks table is created. Because of the reference to the resource (see [[#Constraints|"Constraints"]], the tasks table must be created ''after'' the [[Resources database table|resources table]].
| |
| − |
| |
| − | === Insert ===
| |
| − |
| |
| − | Since a task can only be added in the current container, the <tt>ContainerId</tt> does not have to be supplied but can be retrieved from the [[State variables database table|<tt>StateVariables</tt>]] table.
| |
| − |
| |
| − | === Update ===
| |
| − |
| |
| − | A task can only be updated when it is selected. The selected tasks are stored in the [[Selected tasks database table|selected tasks table]]. This means that the user does not have to supply the id when updating a selected task. This means that the caller must ensure that only one task is selected.
| |
| − |
| |
| − | === Delete ===
| |
| − |
| |
| − | Only selected tasks can be deleted. This means that the user does not have to supply an id, but simply all selected tasks are deleted.
| |
| − |
| |
| − | === Cut ===
| |
| − |
| |
| − | As described in [[Cut selected elements|"Cut selected elements"]], selected elements can be 'cut to the clipboard' by setting the <tt>ContainerId</tt> column to the maximum integer value. Since the <tt>Id</tt> of a task is stored in a [[Types|<tt>uint32</tt>]], this value is explicitly set to 4294967295 (=2<sup>32</sup>).
| |
| − |
| |
| − | === Paste ===
| |
| − |
| |
| − | As described in [[Paste elements|"Paste elements"]], elements can be pasted into the current diagram by setting the <tt>ContainerId</tt> column to the current container. As follows from the previous section, this is done by finding all the tasks that have this <tt>ContainerId</tt> set to the maximum integer value of 4294967295.
| |
| − |
| |
| − | == Implementation ==
| |
| − |
| |
| − | === Interface structure ===
| |
| − |
| |
| − | <syntaxhighlight lang="cpp">
| |
| − | typedef struct
| |
| − | {
| |
| − | uint32 id,
| |
| − | char* name,
| |
| − | char* description,
| |
| − | uint resourceId,
| |
| − | uint x,
| |
| − | uint y,
| |
| − | uint width,
| |
| − | uint height,
| |
| − | uint32 container_id
| |
| − | } tdd_task;
| |
| − | </syntaxhighlight>
| |
| − |
| |
| − | === Create table ===
| |
| − |
| |
| − | <syntaxhighlight lang="sql">
| |
| − | CREATE TABLE Tasks
| |
| − | (
| |
| − | Id INTEGER PRIMARY KEY,
| |
| − | Name TEXT,
| |
| − | Description TEXT,
| |
| − | ResourceId INTEGER REFERENCES Resources(Id) ON DELETE SET NULL,
| |
| − | X INTEGER,
| |
| − | Y INTEGER,
| |
| − | Width INTEGER,
| |
| − | Height INTEGER,
| |
| − | ContainerId INTEGER REFERENCES Tasks(Id) ON DELETE CASCADE
| |
| − | )
| |
| − | </syntaxhighlight>
| |
| − |
| |
| − | === Insert ===
| |
| − |
| |
| − | <syntaxhighlight lang="sql">
| |
| − | INSERT INTO Tasks
| |
| − | (Name,Description, Resource, X, Y, Width, Height, ContainerId)
| |
| − | VALUES (%s, %s, %s, %d, %d, %d, %d, (SELECT Val FROM StateVariables WHERE Name='CurrentContainerId'))
| |
| − | </syntaxhighlight>
| |
| − |
| |
| − | === Update ===
| |
| − |
| |
| − | <syntaxhighlight lang="sql">
| |
| − | UPDATE Tasks SET
| |
| − | Name=%s,
| |
| − | Description=%s,
| |
| − | Resource=%s,
| |
| − | X=%d,
| |
| − | Y=%d,
| |
| − | Width=%d,
| |
| − | Height=%d
| |
| − | WHERE Id IN (SELECT Id FROM SelectedTasks)
| |
| − | </syntaxhighlight>
| |
| − |
| |
| − | === Delete selected tasks ===
| |
| − |
| |
| − | <syntaxhighlight lang="sql">
| |
| − | DELETE FROM Tasks WHERE Id IN (SELECT Id FROM SelectedTasks)
| |
| − | </syntaxhighlight>
| |
| − |
| |
| − | === Cut selected tasks ===
| |
| | | | |
| − | <syntaxhighlight lang="sql">
| + | The following actions are defined: |
| − | UPDATE Tasks SET ContainerId=4294967295 WHERE Id IN (SELECT Id FROM SelectedTasks)
| + | * [[Tasks database table - Create|Create]] |
| − | </syntaxhighlight>
| + | * [[Tasks database table - Insert|Insert]] |
| | + | * [[Tasks database table - Update|Update]] |
| | + | * [[Tasks database table - Delete|Delete]] |
| | + | * [[Tasks database table - Cut|Cut]] |
| | + | * [[Tasks database table - Paste|Paste]] |
| | | | |
| − | === Paste tasks === | + | == References == |
| | + | <references/> |
| | | | |
| − | <syntaxhighlight lang="sql">
| |
| − | UPDATE Tasks SET ContainerId=(SELECT Val FROM StateVariables WHERE Name='CurrentContainerId') WHERE ContainerId=4294967295
| |
| − | </syntaxhighlight>
| |
| | | | |
| | ---- | | ---- |
| | * [[Database]] | | * [[Database]] |
