/back:: vs Context:/back:: : SystemWeaver

B

Bashar Nassar

started a topic almost 7 years ago

Hi,

Mainly /back:: and Context:/back:: have two differences, which are where the operation is performed and the returned set of items.

/back::

Returns a list of all items in the DB which include the current obj as the specified part.

The use of this axis is executed by the server, and is potentially expensive, especially if you run on a slave server.

Note: The use of /back:: is NOT recommended due to the potentially negative effect on performance for all system users.

Example:

<Report>
  <ForEach select="IRSS">
    <ForEach select="/back::IRSS">
      <Text>#{Name}</Text>
    </ForEach>
  </ForEach>
</Report>

Result:

Context:/back::

If you must /back::, it is recommended to use it in a Context since it would not have an impact on system performance.

Returns a list of all items in the current context which include the current obj as the specified part.

The use of this axis is executed by the client, which result in faster performance.

Example:

<Report>
  <Context name="document">
    <AddParts owner="main" sid="IRRS" part="documentSection" defobj="section"/>
    <AddParts owner="section" sid="ISSE" part="subSection" defobj="subSections"/>
  </Context>
  <ForEachInContext name="document" group="section">
    <ForEach select="Context:/back::documentSection">
      <Text>Item name: #{Name} Version:#{Version}</Text>
    </ForEach>
  </ForEachInContext>
</Report>

Result:

Best Regards,
Bashar

Mikael Lagerman

said almost 5 years ago

How to move back in the Context definition? I need something like:

B

Bashar Nassar

said almost 5 years ago

Hi Mikael,

To move back in a context you should do that in two steps

Step 1: You should define your context for example

  <Context name="context1">
    <AddParts owner="main" sid="ARSC" part="softwareComs" defobj="SoftwareComponent"/>
    <AddParts owner="SoftwareComponent" sid="ARPP" part="receiveSignals" defobj="Signal"/>
    <AddParts owner="SoftwareComponent" sid="ARRP" part="sendSignals" defobj="+Signal"/>
  </Context>

Step 2: when you iterate over the defined context, in the above step, you can choose to go forward or backward. To go backward you have two different alternatives which will give the same result, the first alternative is to use the tag <ContextGoBack part="">.

For example

 <ForEachInContext name="context1" group="Signal">  
  <ContextGoBack part="sendSignals">
    <Text>- #{Name}</Text>
  </ContextGoBack>
  </ForEachInContext>

and the second alternative is to use the Path language using Context:/back:: .

For example

  <ForEachInContext name="context1" group="Signal">  
  <ForEach select="Context:/back::sendSignals">
    <Text>- #{Name}</Text>
  </ForEach>
  </ForEachInContext>

Here you can find a full example for how to define a context (Step 1) and then iterate over the defined context with going backward (Step 2)

<Report>
    <Context name="context1">
        <AddParts owner="main" sid="ARSC" part="softwareComs" defobj="SoftwareComponent"/>
        <AddParts owner="SoftwareComponent" sid="ARPP" part="receiveSignals" defobj="+Signal"/>
        <AddParts owner="SoftwareComponent" sid="ARRP" part="sendSignals" defobj="+Signal"/>
    </Context>


    <ForEachInContext name="context1" group="Signal"> 
        <!--Alternative 1--> 
        <ContextGoBack part="sendSignals">
            <Text>- #{Name}</Text>
        </ContextGoBack>
        <!--Alternative 2-->
        <!--
        <ForEach select="Context:/back::sendSignals">
            <Text>- #{Name}</Text>
        </ForEach>
        -->
    </ForEachInContext>
</Report>

For more information about how to use context please visit SystemWeaver Script Language - Introductory Training

Thanks,

Bashar

Mikael Lagerman

said almost 5 years ago

Thanks Bashar

My problem with this context of mine is I need to define the context with two "heads". The Post is not subordinated to the main, As I try to illustrate in the attached picture I need to go from main down to a Product Function item. From this I need to back up via a different part to the Post, and from there down into the PHAR analysis via a third part.

The trick to define an item to a context when this item is outside the main sub-structure I understand is to define it (the Post) as the value of a Parameter. In syntax this seams to work and I have followed several examples in the documentation and at the support.systemweaver.se (e.g. https://support.systemweaver.se/support/discussions/topics/31000002342?page=1), but this fails for me with the "Please select Parameter" error message in the generated document/report.

Context PHAR...

(55.4 KB)

B

Bashar Nassar

said almost 5 years ago

Hello again,

If I understood your use case correctly then using a context with parameter will solve your issue. If you have the need to select a value that is on a higher level than your main item then you can use parameter, i.e., define a Parameter to select the Post value in you case. Here I am including an example for how to do that:

<Report>

    <Parameters>
        <Parameter caption="Analysis Area" name="p1" hintContextPath="I2AHA;DEIT"/>
        <ForEachPathReference path="I2AHA;DEIT">
            <AddParameterValue name="p1"/>            
        </ForEachPathReference>
    </Parameters>


    <Context name="HARAContext">
        <AddParts owner="p1" sid="I2AHA" part="AnalysisToHARA" defobj="HARA"/>
        <AddParts owner="HARA" sid="DEIT" part="AnalysisToItem" defobj="main"/>
        <AddParts owner="HARA" sid="DEHA" part="AnalysisToHazard" defobj="Haz"/>
        <AddParts owner="HARA" sid="DEHE" part="AnalysisToHazEv" defobj="HazEv"/>
        <AddParts owner="HARA" sid="DESG" part="AnalysisToSafetyGoal" defobj="SafetyGoal"/>
        <AddParts owner="main" sid="I2SID" part="ItemToDetail" defobj="Detail"/>
        <AddParts owner="main" sid="I2IRQ" part="ItemToDetail" defobj="+Detail"/>
        <AddParts owner="SafetyGoal" sid="SGDF" part="SafetyGoalToHazEv" defobj="+HazEv"/>
        <AddParts owner="HazEv" sid="HEH" part="HazEvToHaz" defobj="+Haz"/>
        <AddParts owner="Haz" sid="I2HO" part="HazToDetail" defobj="Detail"/>
        <AddParts owner="Haz" sid="I2HARQ" part="HazToDetail" defobj="Detail"/>
    </Context>

  
    <ForEachInContext name="HARAContext" group="main">
        <ForEach select="Context:/back::AnalysisToItem/AnalysisToSafetyGoal">
        <Text>#{Name}</Text>
    </ForEach> 
    </ForEachInContext>
</Report>

Thanks,

Bashar

Mikael Lagerman

said almost 2 years ago

Related to this,another case.

</ApplyTemplate>

This results in an Syntax Error(-23): ":" found

</ApplyTemplate>

This results in an empty list.

It seamse breaking up the statement helps:

</ApplyTemplate>

Works but results in additional non-related items to be included. (one could secure all items belong to this structure but Context would automatically handle this.)

This is what I would prefer:

</ApplyTemplate>

but this results in an empty list with no items. Adding "Context:" results in syntax errors...

How to best do these conditional Context expressions? This I missed in the available articles and client help.

In this case we also have performance issues why use of Context is double beneficial.

Mikael Lagerman

said almost 2 years ago

Solved it eventually:
<Variable name="RelItems" select="Context:/FTAtoRelPC/RelPcToPC" as="[Item]"/>        
<Variable name="PC" select="Context:$RelItems[/back::StructureToPC]" as="[Item]"/>        
or
<WithParam name="SelectedPC" select="Context:$RelItems[/back::StructureToPC]" as="[Item]"/>

SystemWeaver Support

said almost 2 years ago

Great Mikael! Glad you found a solution. And, thanks for your participation in the Forum!

When traversing a context in the path language, "Context:" should start the expression, as you have in your example.

Users can find further examples and information about Context in the application Help.

SystemWeaver Support

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