So in my targets file, I've got a line that looks like this:
<XmlPeek Namespaces="" XmlInputPath="file.xml" Query="/data/#AttributeOne">
<Output TaskParameter="Result" ItemName="my_AttributeOne" />
</XmlPeek>
in "file.xml", I have:
<data AttributeOne="abc" AttributeTwo="def" />
it also reads a few other attributes.
When the attribute has data, everything works fine... but when I leave AttributeOne as an empty string (""), XmlPeek blows chunks with the following error:
The "XmlPeek" task's outputs could not be retrieved from the "Result" parameter. Parameter "includeEscaped" cannot have zero length.
if I remove the attribute ENTIRELY, it works fine (the resulting item is obviously and understandably blank)
The question is... how can I DETERMINE, WITHOUT blowing chunks, the value of a blank attribute... whether by pre-testing for a value, or by correctly handling the blank, or some other means.
CONSTRAINT: the only real requirement is to stick to the built-in tasks (XmlPeek)... I'm aware of XmlRead in the community tasks... for various reasons, I want to use out-of-the-box tasks.
Thanks in advance!
The error happens because an empty string is being used as the Item Identifier. I guess identifiers cannot be the empty string. If you remove the attribute then the result is null and no Item is created so that's why that doesn't throw an error.
Maybe try return the result as a Property instead of an Item.
If you do not need to distinguish between the attribute being omitted versus having an empty value, you can prevent the error by inserting the condition [#AttributeOne!=''] into the query as follows.
<XmlPeek Namespaces="" XmlInputPath="file.xml" Query="/data[#AttributeOne!='']/#AttributeOne">
<Output TaskParameter="Result" ItemName="my_AttributeOne" />
</XmlPeek>
Related
I have an MSBuild SDK that we use for our projects. We define various default properties and add custom items depending on the project type. Some of those items are added in the SDK.targets, after the user project is parsed.
I found a situation where I'd like to add some items but only if the user does not have them added themselves (to use whatever metadata values they have set).
Best way I found to achieve that is the following:
<Target Name="IncludeDefaults">
<ItemGroup>
<CustomItem Include="Foo" Value="Default"
Condition="#(CustomItem->Equals('Foo')->Distinct()) == 'False'"/>
</ItemGroup>
</Target>
I know I can exclude items using Remove but that only ignores exact matches, including metadata. I tried various other combinations of attributes and processing to get around that but nothing seems to have worked.
In particular I have multiple items to add with default metadata so I'm looking for a single line solution.
Is this the best way of doing it, or is there something I'm missing?
If I understand correctly, you have named data values and you want to provide default values if values have not already been provided.
Consider using properties.
The following example is very idiomatic MSBuild. The Condition tests that the property does not already have a value.
<PropertyGroup>
<Foo Condition="'$(Foo)' == ''">Default</Foo>
<Bar Condition="'$(Bar)' == ''">AnotherDefault</Bar>
</PropertyGroup>
In addition to PropertyGroup elements in files, properties can be defined by environment variables and by the command line /p switch so there is a lot of flexibility with defining and overriding properties.
But your question is about ItemGroup and I may be making an incorrect assumption about your intent.
Remove is for removing items that are already in the ItemGroup collection.
There is an Exclude that works with Include and behaves as a 'deny' list. In the following example if there is already a 'Foo' item in 'CustomItem', it will be excluded from the Include.
<ItemGroup>
<CustomItem Include="Foo" Value="Default" Exclude="#(CustomItem)"/>
</ItemGroup>
The Exclude doesn't check metadata. It only compares the names. If CustomItem has items 'Foo' and 'Bar', then #(CustomItem) will be 'Foo;Bar' and 'Foo' will denied from the Include.
I'm trying to use MSBuild items to list the number of wildcard paths that can be evaluated in relation to a as-yet-unknown base path. As such, I'd like to be able to write:
<Item Include="Content\**\*.js" />
But not evaluate that as a path, but instead add it as a simple item whose %(Identity) is still the string "Content\**\*.js".
Is this possible in MSBuild?
As you have discovered, the item identity needs to be escaped. MSbuild has intrinsic functions to do this easily so you don't need to look up every character:
<ItemGroup>
<Item Include="$([MSBuild]::Escape('Content\**\*'))" />
</ItemGroup>
As is often the case, I discovered the answer immediately after posting.
As per MSBuild Special Characters, I need to escape the asterisk as %2A
I tried to have a condition on a Target tag, but resulted with the error:
target has a reference to item metadata. References
to item metadata are not allowed in target conditions unless they are part of an item transform.
So i found this work around:
How to add item transform to VS2012 .proj msbuild file
and tried to implement it, but i can't figure up what i am doing wrong because it's not working as expected.
<CallTarget Targets="CopyOldWebConfigJs" />
<Target Name="CopyOldWebConfigJs"
Inputs="#(ContentFiltered)"
Outputs="%(Identity).Dummy"
DependsOnTargets="webConfigJsCase">
<Message Text="web.config.js Case" />
</Target>
<!-- New target to pre-filter list -->
<Target Name="webConfigJsCase"
Inputs="#(FileToPublish)"
Outputs="%(Identity).Dummy">
<ItemGroup>
<ContentFiltered Condition="$([System.Text.RegularExpressions.Regex]::IsMatch('%(FileToPublish.Filename)%(FileToPublish.Extension)', 'web.config.js'))" />
</ItemGroup>
</Target>
I thought that Inputs="#(ContentFiltered)" will contain the lines that DependsOnTargets="webConfigJsCase" find.
But when i run it , i am getting this message: Skipping target "CopyOldWebConfigJs" because it has no inputs.
I know for a fact that the regex work, and it do find a filename_ext that equals web.config.js so it return True
What do i do or understand wrong?
In <ItemGroup><Item/></ItemGroup>, no change will be made to the Item item because no action was specified. If you want to add entries to the item, you must specify Include="".
The <Item/> documentation describes the various attributes for item elements inside of an <ItemGroup/>. Note that at the top-level of an MSBuild file, directly under the <Project/> element, you would use the attributes Include and Exclude while in a <Target/> you would use the attributes Include and Remove. Not including any attributes at all is nonsensical and—as far as I know—no different than simply deleting the entire line. I am surprised MSBuild doesn’t throw an error or warning this is almost certainly a mistake and not intentional.
The Inputs and Outputs attributes on your <Target Name="webConfigJsCase"/> are unnecessary. In fact, they slow MSBuild down by making it loop over the target unnecessarily. You can filter just in the <Item/> like this:
<Target Name="webConfigJsCase">
<ItemGroup>
<ContentFiltered Condition="'%(FileToPublish.Filename)%(FileToPublish.Extension)' == 'web.config.js'" Include="#(FileToPublish)" />
</ItemGroup>
</Target>
Additionally, I assume that you intended your regular expression to match web.config.js but not match webaconfigbjs. You don’t need to use an advanced feature like Regular Expressions here because MSBuild’s built-in condition operators already support simple string comparison. If fixed the condition above to be more readable.
i need your help. I am running into a situation. I am trying to copy certain binaries into a particular folder. I am adding those task into "AfterCompileSolution" . I know it is incorrect, bcos it's gonna execute this step after every solution is compiled.
Here is my situation, i tried adding a condition like a SolutionFileName, but i get empty result. The target doesn't get executed because the SolutionFileName parameter is empty.
So do you know of any parameter that i can use between solutiontobuild i.e i want to copy certain binaries only after solution "A" is completed and i want these parameters to be part of "AfterCompileSolution" or maybe "BeforeCompileSolution"
Please suggest
Thanks
Satesh
It's been a while since I've done this but I believe you reference the file name with a syntax such as:
<Target Name="AfterCompileSolution" DependsOnTargets="RandomPreReqTarget">
<SomeTask Condition="'%(SolutionToBuildItem.Identity)' == 'ConditionValue'" />
</Target>
Another cool thing you can do is product extra properties in your SolutionToBuild item and reference them as metadata also like:
<SolutionToBuild Include="$(SolutionRoot)\$(SourceBranch)\RandomDirectory\Project.csproj">
<Targets>Build</Targets>
<Properties>OutDir=$(RandomDirectory);Configuration=$(Configuration);Platform=AnyCPU</Properties>
<GAC>True</GAC>
</SolutionToBuild>
You would then be able to access the metadata like this:
<Target Name="AfterCompileSolution" DependsOnTargets="RandomPreReqTarget">
<SomeTask Condition="'%(SolutionToBuildItem.GAC)' == 'True'" />
</Target>
So I'm kinda getting the hang of writing in MSBuild.
I like the idea storing things in ItemGroups because its easy to iterate, and you can have multple fields.
That makes them sort of like a class (more like a struct) but they respond to the iteration syntax of targets and tasks in a way that feels like a lambda expression.
However I continue to run into situation where I want to access a value of a particular item in an item group, that is, to access it like a property.
In that case I run into the issue of how to isolate a single item within the group.
When the item group is batching in a target or task, because of addressing using a metadata name or because of addressing with the common itemgroup name, you can utilize the value of the 'current' item i.e. #(ItemsName) or %(MetaDataName).
But I want to do things like: use an Item group as a System.Configuration class that contains the values of the entries in a section of a config file. Therefore the normal thing would be to name the ItemGroup itself to match the section name in the config file. however, the ItemGroup is not an addressable element that is accessible through the build engine interface, only the items themselves are addressable.
It might be nice to individually name the items in an ItemGroup rather than name them all the same and use the Include or a metadata field like to distinguish among them. This makes them behave like properties in that they are individually addressable as distinct items. so you could easily use their values in Conditions this way: '#(UniqueItemName->'%(Value)').
However, then the iterable features are essentially lost.
To narrow this down, presume i have a config file that gets read into an Item group by and xml task so that the element names in a section become the name of the items in the item group and attributes of each config file element are attributes that become metadata:
<configItemFlag name="displayDebugMessages" value="true" note="use with abandon" />
<configItemFlag name="displaySecurityValueMessages" value="false" note="use with caution" />
When I want to test this in a Condition, I need to narrow it down to something like this:
<Messge Text="Debug Message: you are debugging!" Condition="'#(configItemFlag->'%(Name)')' == 'displayDebugMessages' AND '#(configItemFlag->'%(Value)')' == 'true'/>
But this only evaluates the comparison and frequently does not evaluate to a single boolean.
So is there any way to syntacticly get this down to a dependable test?
Does this work for what you are trying to do?
<ItemGroup>
<ConfigItemFlag Include="displayDebugMessages">
<Value>true</Value>
<Note>use with abandon</Note>
</ConfigItemFlag>
<ConfigItemFlag Include="displaySecurityValueMessages">
<Value>false</Value>
<Note>use with caution</Note>
</ConfigItemFlag>
</ItemGroup>
<Target Name="Build">
<Message
Condition="
'%(ConfigItemFlag.Identity)' == 'displayDebugMessages' AND
'%(Value)' == 'true'"
Text="Debug Message: you are debugging, %(Note)!"
/>
</Target>
Output:
Build:
Debug Message: you are debugging, use with abandon!
(response to comment)
...the only thing I can offer to be able to use meta as properties isn't all that great, unless the target will make heavy use of them throughout. Basically it involves flattening each item to properties by batching on the item and creating local properties with each batch.
<Target Name="BuildOne"
Outputs="%(ConfigItemFlag.Identity)">
<!-- flatten this batch to properties -->
<PropertyGroup>
<_Identity>%(ConfigItemFlag.Identity)</_Identity>
<_Value>%(ConfigItemFlag.Value)</_Value>
<_Note>%(ConfigItemFlag.Note)</_Note>
</PropertyGroup>
<!-- use meta as properties -->
<Message
Condition="
'$(_Identity)' == 'displayDebugMessages' AND
'$(_Value)' == 'true'"
Text="Debug Message: you are debugging, $(_Note)!"
/>
</Target>
<Target Name="Build" DependsOnTargets="BuildOne"
/>
It seems like you are running into some of the limitations of the msbuild scripting language. Have you thought about writing a custom task to perform what you are looking for? That way you would be able to bring the full power of a full programming language to bear against the simple conditional check you want to perform.