/// <summary>
/// Create a new template context containing the specified merge fields.
/// </summary>
/// <param name="mergeFields"></param>
/// <returns></returns>
protected override ILavaRenderContext OnCreateRenderContext()
{
var fluidContext = new global::Fluid.TemplateContext(_templateOptions);
var context = new FluidRenderContext(fluidContext);
return(context);
}
/// <summary>
/// Registers a set of Liquid-style filter functions for use with the Fluid templating engine.
/// The original filters are wrapped in a function with a Fluid-compatible signature so they can be called by Fluid.
/// </summary>
/// <param name="lavaFilterMethod">The MethodInfo object that describes the function.</param>
/// <param name="filterName">The Lava name for the filter.</param>
protected override void OnRegisterFilter(MethodInfo lavaFilterMethod, string filterName)
{
var lavaFilterMethodParameters = lavaFilterMethod.GetParameters();
if (lavaFilterMethodParameters.Length == 0)
{
return;
}
var templateOptions = GetTemplateOptions();
filterName = filterName ?? lavaFilterMethod.Name;
// The first argument passed to the Lava filter is either the Lava Context or the template input.
var hasContextParameter = lavaFilterMethodParameters[0].ParameterType == typeof(ILavaRenderContext);
var firstParameterIndex = 1 + (hasContextParameter ? 1 : 0);
// Define the Fluid-compatible filter function that will wrap the Lava filter method.
ValueTask <FluidValue> fluidFilterFunction(FluidValue input, FilterArguments arguments, TemplateContext context)
{
var lavaFilterMethodArguments = new object[lavaFilterMethodParameters.Length];
for (int i = 0; i < lavaFilterMethodParameters.Length; i++)
{
FluidValue fluidFilterArgument = null;
// Get the value for the argument.
if (i == 0)
{
// If this is the first parameter, it may be a LavaContext or the input template.
if (hasContextParameter)
{
lavaFilterMethodArguments[0] = new FluidRenderContext(context);
continue;
}
else
{
fluidFilterArgument = input;
}
}
else if (i == 1 && hasContextParameter)
{
// If this is the second parameter, it must be the input template if the first parameter is a LavaContext.
fluidFilterArgument = input;
}
else if (arguments.Count > (i - firstParameterIndex))
{
// This parameter is a filter argument.
fluidFilterArgument = arguments.At(i - firstParameterIndex);
}
if (fluidFilterArgument == null && lavaFilterMethodParameters[i].IsOptional)
{
lavaFilterMethodArguments[i] = lavaFilterMethodParameters[i].DefaultValue;
}
else
{
lavaFilterMethodArguments[i] = GetLavaParameterArgumentFromFluidValue(fluidFilterArgument, lavaFilterMethodParameters[i].ParameterType);
}
}
try
{
var result = lavaFilterMethod.Invoke(null, lavaFilterMethodArguments);
return(FluidValue.Create(result, templateOptions));
}
catch (TargetInvocationException ex)
{
// Any exceptions thrown from the filter method are wrapped in a TargetInvocationException by the .NET framework.
// Rethrow the actual exception thrown by the filter, where possible.
throw ex.InnerException ?? ex;
}
}
templateOptions.Filters.AddFilter(filterName, fluidFilterFunction);
}