/// <summary>
/// Tries to get the value for the specified key.
/// </summary>
/// <remarks>
/// This method will also materialize <see cref="IMetadataValue"/> and
/// evaluate script strings (a key that starts with "=>" will be treated
/// as a script and evaluated).
/// </remarks>
/// <param name="metadata">The metadata instance.</param>
/// <typeparam name="TValue">The desired return type.</typeparam>
/// <param name="key">The key of the value to get. If the key is <c>null</c>, this will return the default value.</param>
/// <param name="value">The value of the key if it was found and could be converted to the desired return type.</param>
/// <returns><c>true</c> if the key was found and the value could be converted to the desired return type, <c>false</c> otherwise.</returns>
public static bool TryGetValue <TValue>(
this IMetadata metadata,
string key,
out TValue value)
{
if (metadata != null && key != null)
{
// Script
if (IScriptHelper.TryGetScriptString(key, out string script))
{
IExecutionContext context = IExecutionContext.Current;
object result = context.ScriptHelper.EvaluateAsync(script, metadata).GetAwaiter().GetResult();
return(TypeHelper.TryExpandAndConvert(result, metadata, out value));
}
// Value
if (metadata.TryGetRaw(key, out object raw))
{
return(TypeHelper.TryExpandAndConvert(raw, metadata, out value));
}
}
value = default;
return(false);
}
public static bool TryGetScriptMetadataValue(string key, object value, IExecutionState executionState, out ScriptMetadataValue scriptMetadataValue)
{
scriptMetadataValue = default;
if (value is string stringValue && IScriptHelper.TryGetScriptString(stringValue, out string script))
{
scriptMetadataValue = new ScriptMetadataValue(
key,
stringValue.Substring(0, stringValue.Length - script.Length),
script,
executionState);
return(true);
}
return(false);
}