/// <summary>
/// Write as an asynchronous operation.
/// </summary>
/// <param name="scope">The scope.</param>
/// <param name="block">The block.</param>
/// <param name="token">The cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
/// <returns>A Task representing the asynchronous operation.</returns>
/// <exception cref="System.NotSupportedException">'where' should be a string expression but instead found '{oWhere.GetType().Name}'</exception>
public override async Task WriteAsync(ScriptScopeContext scope, PageBlockFragment block, CancellationToken token)
{
var htmlAttrs = await block.Argument.GetJsExpressionAndEvaluateAsync(scope) as Dictionary <string, object>;
var hasEach = false;
IEnumerable each = null;
var binding = "it";
var hasExplicitBinding = false;
JsToken where = null;
if (htmlAttrs != null)
{
if (htmlAttrs.TryGetValue("if", out var oIf))
{
if (DefaultScripts.isFalsy(oIf))
{
return;
}
htmlAttrs.Remove("if");
}
if (htmlAttrs.TryGetValue(nameof(where), out var oWhere))
{
if (oWhere is not string whereExpr)
{
throw new NotSupportedException($"'where' should be a string expression but instead found '{oWhere.GetType().Name}'");
}
where = whereExpr.GetCachedJsExpression(scope);
htmlAttrs.Remove(nameof(where));
}
if (htmlAttrs.TryGetValue(nameof(each), out var oEach))
{
hasEach = true;
htmlAttrs.Remove(nameof(each));
}
each = oEach as IEnumerable;
if (htmlAttrs.TryGetValue("it", out var oIt) && oIt is string it)
{
binding = it;
hasExplicitBinding = true;
htmlAttrs.Remove("it");
}
if (htmlAttrs.TryGetValue("class", out var oClass))
{
var cls = scope.Context.HtmlMethods.htmlClassList(oClass);
if (string.IsNullOrEmpty(cls))
{
htmlAttrs.Remove("class");
}
else
{
htmlAttrs["class"] = cls;
}
}
}
var attrString = scope.Context.HtmlMethods.htmlAttrsList(htmlAttrs);
if (HtmlScripts.VoidElements.Contains(Tag)) //e.g. img, input, br, etc
{
await scope.OutputStream.WriteAsync($"<{Tag}{attrString}>{Suffix}", token).ConfigAwait();
}
else
{
if (hasEach)
{
var hasElements = each != null && each.GetEnumerator().MoveNext();
if (hasElements)
{
await scope.OutputStream.WriteAsync($"<{Tag}{attrString}>{Suffix}", token).ConfigAwait();
var index = 0;
var whereIndex = 0;
foreach (var element in each)
{
// Add all properties into scope if called without explicit in argument
var scopeArgs = !hasExplicitBinding && CanExportScopeArgs(element)
? element.ToObjectDictionary()
: new Dictionary <string, object>();
scopeArgs[binding] = element;
scopeArgs[nameof(index)] = AssertWithinMaxQuota(whereIndex++);
var itemScope = scope.ScopeWithParams(scopeArgs);
if (where != null)
{
var result = await where.EvaluateToBoolAsync(itemScope);
if (!result)
{
continue;
}
}
itemScope.ScopedParams[nameof(index)] = AssertWithinMaxQuota(index++);
await WriteBodyAsync(itemScope, block, token).ConfigAwait();
}
await scope.OutputStream.WriteAsync($"</{Tag}>{Suffix}", token).ConfigAwait();
}
else
{
await WriteElseAsync(scope, block.ElseBlocks, token).ConfigAwait();
}
}
else
{
await scope.OutputStream.WriteAsync($"<{Tag}{attrString}>{Suffix}", token).ConfigAwait();
await WriteBodyAsync(scope, block, token).ConfigAwait();
await scope.OutputStream.WriteAsync($"</{Tag}>{Suffix}", token).ConfigAwait();
}
}
}
