public override async Task <object> Evaluate(EvaluationContext ctx)
{
var listCandidate = await ListCandidate.Evaluate(ctx);
if (listCandidate == null)
{
// Template indexer implements null propagation out of the box
return(null);
}
if (listCandidate is IList list)
{
if (Index < 0 || Index >= list.Count)
{
// Template indexer implements null propagation out of the box
return(null);
}
return(list[Index]);
}
else
{
throw new TemplateException($"Indexer '#{Index}' is only valid on model entity lists.");
}
}
public override async Task GenerateOutput(StringBuilder builder, EvaluationContext ctx, Func <string, string> encodeFunc = null)
{
if (ListCandidate != null && Template != null)
{
var listObj = (await ListCandidate.Evaluate(ctx)) ?? new List <object>();
if (listObj is IList list)
{
int index = 0;
foreach (var listItem in list)
{
// Initialize new evaluation context with the new variable in it
var scopedCtx = ctx.Clone();
scopedCtx.SetLocalVariable(IteratorVariableName, new EvaluationVariable(
evalAsync: () => Task.FromResult(listItem),
selectResolver: () => AsyncUtil.Empty <Path>(), // It doesn't matter when generating output
pathsResolver: () => AsyncUtil.Empty <Path>() // It doesn't matter when generating output
));
// Index, useful for setting line numbers
scopedCtx.SetLocalVariable(IteratorVariableName + "_index", new EvaluationVariable(
evalAsync: () => Task.FromResult <object>(index),
selectResolver: () => AsyncUtil.Empty <Path>(), // It doesn't matter when generating output
pathsResolver: () => AsyncUtil.Empty <Path>() // It doesn't matter when generating output
));
// Run the template again on that context
await Template.GenerateOutput(builder, scopedCtx, encodeFunc);
index++;
}
}
else
{
throw new TemplateException($"Foreach expression could not be applied. Expression ({ListCandidate}) does not evaluate to a list.");
}
}
}