Runtime script evaluation in Grails - Best Practicse - grails

In our application, numerous emails are being sent from the system. These emails were of the same format for all users with different contextual variables populating the dynamic data.
We are now planning a feature to allow administrators to edit and customize these templates. As such the plan is to use the groovy shell to evaluate the templates at run time e.g.
Binding binding = new Binding();
binding.setVariable("model", [var1: "First Name", var2: "Last Name"])
GroovyShell shell = new GroovyShell(binding);
Object email = shell.evaluate('return "<html><title>Test Shell</title><body>${model.var1} ${model.var2}</body></html>";');
This seems to work adequately for us. The questions I have are:
Is the GroovyShell the preferred engine to use or is Rhino or other better?
Are there any performance concerns or memory issues to be aware of? Any low hanging fruit we can optimize i.e. can the shell or binding be reused
What's the biggest bottleneck in the above code? The construction? The evaluation?
thanks

I would recommend using something like GroovyPagesTemplateEngine because it goes beyond just Groovy eval and you and you can use all the grails taglib goodness as well. I'm using both GroovyPagesTemplateEngine and SimpleTemplateEngine for your exact scenario.
SimpleTemplateEngine is slightly faster so if I don't need much more than simple binding I use it. When I need to deal with logic and control structures, I use GroovyPagesTemplateEngine.

For grails, use the page rendering api instead. http://grails.org/doc/2.0.x/guide/introduction.html#whatsNew

Related

Can I define new mustache template variables in swagger-codegen?

I have developed a rest-api client (in java) customised to the needs of my product. I wanted to generate tests using my rest api client using swagger-codegen modules based on yaml-file.
I have already extended DefaultCodegenConfig & even tried implementing the CodegenConfig interface to build my custom jar. I have customized the api.mustache and api_test.mustache files and passing them in the constructor and processOpts() method of my CustomCodeGen that extends DefaultCodegenConfig.
However, I want to use the custom/new mustache template variables that I have added in my customised api.mustache.
For e.g. if refer to standard api.mustache, the template variables it typically uses are
- {{classname}}
- {{#operation}}
- {{#contents}}
- {{#parameters}}
etc.
Now, I want to introduce a new template variable, let's say {{custom_param}}. Now I am not clear how do I integrate this new template variable with the implementation.
Looks like from this Mustache-Template-Variables published here, swagger-codegen does not allow adding new template-variables and perhaps we are restricted to only the variables mentioned on this page.
So, is there some way to make the new template variables work ?
Some time ago I added the uniqueItems parameter for bean validation as it was not getting processed by the engine even though it was a part of the implemented JSR.
So I believe codebase needs to be updated to use your own variable which is only possible if you fork the code.
In case it helps, these two were the PRs:
For query parameters: https://github.com/swagger-api/swagger-codegen/pull/10154.
For body parameters: https://github.com/swagger-api/swagger-codegen/pull/10490.

Can I use url parameters in LESS css?

Intro:
I'm trying out LESS in an asp.net mvc environment.
I use dotless for server side processing (and I wouldn't want to use client side processing especially afer publishing the complete project).
I have to apply a design where there are different color schemes depending on different things (e.g. time of the day).
Less felt very powerful in this case as designing a parameterized css and only changing like 10 variables at the beginning of the file for every theme was really uplifting.
Problem:
But I would need to somehow change the color themes from an outside parameter.
Ideas:
First I thought that an URL parameter like style.less?theme=fuschia would be good, but I found no way to parse something like this.
Then I thought that making a very short blue.less, green.less, orange.less consisting only declared color variables, and including the main.less in every one of them would be a solid solution.
I had no chance to try out the second solution, but I thought this would be a good time to ask for advice on the most robust way of doing this.
The problem again is: I want to control some things in my less file from the outside.
Yes you can (because I implemented that feature for exactly that reason).
Dotless supports parameters from the outside via the querystring parameter.
<link rel="stylesheet" href="style.less?foo=bar" />
Will let you use the following less:
#foo = bar;
The parameter injection code is very simple. it just prepends the variable declarations to your normal less file, so anything that comes as a querystring parameter will follow the above syntax.
The code in question is very simple: https://github.com/dotless/dotless/blob/master/src/dotless.Core/Engine/ParameterDecorator.cs
AFAIK, you cannot pass parameters for dotnetless to use to do the compile.
As a suggestion, why not just call different less files? This would be fairly easy to do by using a Viewbag property.
To make the different less ones, You first create a less file with each set of colors in them. Then you import your base css file. dotnetless will merge the color definations in the parent file with the usages in the base file. So you have something like -
#baseGray: #ddd;
#baseGrayDark: darken(#baseGray, 15%);
#baseGrayLight: lighten(#baseGray, 10%);
#import "baseCss.less";
I just tested this on and MVC3 project and it works.

IntelliJ Idea auto-complete for my own grails domain meta class methods?

I'm using IntelliJ Idea 10 IDE for my grails development and while it's great at working out the "standard" meta class methods on, for example, domain classes (save, findBy etc), it (obviously) can't pick up methods added by plugins or my own code.
While I don't expect the IDE to be able to pick these up automatically, I'm optimistically wondering if there's a way to tell IntelliJ that, for example, "myMethod" is added to all domain objects, and that it takes a map and returns "myType".
It's a long shot I know, but does anyone know how this might be done in config, a plugin, or by some smoke-and-mirrors so I can a) stop missing simple, stupid typos and b) get some auto-complete?
I think you're looking for the GroovyDSL scripting framework
http://confluence.jetbrains.net/display/GRVY/Scripting+IDE+for+DSL+awareness
its possible to save a *.gdsl file somethere in src dir, with content:
contributor(context()) {
def scope = com.intellij.psi.search.GlobalSearchScope.allScope(project);
delegatesTo(com.intellij.psi.JavaPsiFacade.getInstance(project).findClass('org.grails.datastore.gorm.GormStaticApi', scope)) delegatesTo(com.intellij.psi.JavaPsiFacade.getInstance(project).findClass('org.grails.datastore.gorm.GormEntity', scope))}

Scaffolding Web Services in Grails

I need to implement a web app, but instead of using relational database I need to use different SOAP Web Services as a back-end. An important part of application only calls web services and displays the result. Since Web Services are clearly defined in form of Operation: In parameters and Return Type it seems to me that basic GUI could be easily constructed just like in the case of scaffolding based on Domain Entities.
For example in case of SearchProducts web service operation I need to enter search parameters as input, so the search page can be constructed. Operation will return a list of products, so I need a page that will display this list in some kind of table.
Is there already some library in grails that let you achieve this. If not, how would you go about creating one?
Probably the easiest approach is to use wsimport on the WSDL files to generate the client-side stubs. Then you can call methods in the stubs from Groovy just as you would have called them from Java.
For example, consider the WSDL file for Microsoft's TerraServer, located at http://terraservice.net/TerraService.asmx?wsdl . Then you run something like
wsimport -d src -keep http://terraservice.net/TerraService.asmx?WSDL
which puts all the compiled stubs in the src directory. Then you can write Groovy code like
import com.terraserver_usa.terraserver.*;
TerraServiceSoap sei = new TerraService().getTerraServiceSoap()
Place home = new Place(city:'Boston',state:'MA',country:'US')
def pt = sei.convertPlaceToLonLatPt(home)
println "$pt.lat, $pt.lon"
assert Math.abs(pt.lat - 42.360000) < 0.001
assert Math.abs(pt.lon - -71.05000) < 0.001
If you want to access a lot of web services, generate the stubs for all of them. Or you can use dynamic proxies instead.
The bottom line, though, is to let Java do what it already does well, and use Groovy where it makes your life easier.
You should be able to use XFire or CXF Plugins. For automatic scaffolding, modify your Controller.groovy template in scaffolding templates so it auto-generates methods you need.

statically analysing Lua code for potential errors

I'm using a closed-source application that loads Lua scripts and allows some customization through modifying these scripts. Unfortunately that application is not very good at generating useful log output (all I get is 'script failed') if something goes wrong in one of the Lua scripts.
I realize that dynamic languages are pretty much resistant to static code analysis in the way C++ code can be analyzed for example.
I was hoping though, there would be a tool that runs through a Lua script and e.g. warns about variables that have not been defined in the context of a particular script.
Essentially what I'm looking for is a tool that for a script:
local a
print b
would output:
warning: script.lua(1): local 'a' is not used'
warning: script.lua(2): 'b' may not be defined'
It can only really be warnings for most things but that would still be useful! Does such a tool exist? Or maybe a Lua IDE with a feature like that build in?
Thanks, Chris
Automated static code analysis for Lua is not an easy task in general. However, for a limited set of practical problems it is quite doable.
Quick googling for "lua lint" yields these two tools: lua-checker and Lua lint.
You may want to roll your own tool for your specific needs however.
Metalua is one of the most powerful tools for static Lua code analysis. For example, please see metalint, the tool for global variable usage analysis.
Please do not hesitate to post your question on Metalua mailing list. People there are usually very helpful.
There is also lua-inspect, which is based on metalua that was already mentioned. I've integrated it into ZeroBrane Studio IDE, which generates an output very similar to what you'd expect. See this SO answer for details: https://stackoverflow.com/a/11789348/1442917.
For checking globals, see this lua-l posting. Checking locals is harder.
You need to find a parser for lua (should be available as open source) and use it to parse the script into a proper AST tree. Use that tree and a simple variable visibility tracker to find out when a variable is or isn't defined.
Usually the scoping rules are simple:
start with the top AST node and an empty scope
item look at the child statements for that node. Every variable declaration should be added in the current scope.
if a new scope is starting (for example via a { operator) create a new variable scope inheriting the variables in the current scope).
when a scope is ending (for example via } ) remove the current child variable scope and return to the parent.
Iterate carefully.
This will provide you with what variables are visible where inside the AST. You can use this information and if you also inspect the expressions AST nodes (read/write of variables) you can find out your information.
I just started using luacheck and it is excellent!
The first release was from 2015.

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