Render scriban template from json data

Question

I would like to render a Scriban template with an ExpandoObject or any other data type that can be generated from a JSON string:

var json = "....";                
var dyn = JsonConvert.DeserializeObject<ExpandoObject>(json);                    
var template = Scriban.Template.Parse("Hello {{ data.foo }}!");                    
var result = template.Render(dyn);

Scriban does not work with ExpandoObjects, as they are parsed as a list of { key = '', value = '' } objects. Declaring a type for the data is not an option in my use case as the JSON schema is not known a priori.

Casting ExpandoObject to dynamic shows the same behavior as using ExpandoObject directly.
I've tried deserializing the JSON to dynamic which leads to an exception:

System.Reflection.TargetParameterCountException: "Parameter count mismatch."

Can I somehow convert the data or configure Scriban to render dynamic data?

score 5 · Accepted Answer · answered Apr 18 '20 at 08:34

Based on the previous answer this is a solution for complex objects:

public static class ScribanRenderer
{
    public static string RenderJson(string json, string content)
    {

        var expando = JsonConvert.DeserializeObject<ExpandoObject>(json);
        var sObject = BuildScriptObject(expando);
        var templateCtx = new Scriban.TemplateContext();
        templateCtx.PushGlobal(sObject);
        var template = Scriban.Template.Parse(content);
        var result = template.Render(templateCtx);

        return result;
    }

    private static ScriptObject BuildScriptObject(ExpandoObject expando)
    {
        var dict = (IDictionary<string, object>) expando;
        var scriptObject = new ScriptObject();

        foreach (var kv in dict)
        {
            var renamedKey = StandardMemberRenamer.Rename(kv.Key);

            if (kv.Value is ExpandoObject expandoValue)
            {
                scriptObject.Add(renamedKey, BuildScriptObject(expandoValue));
            }
            else
            {
                scriptObject.Add(renamedKey, kv.Value);
            }
        }

        return scriptObject;
    }
}

It leverages the fact that complex properties of an ExpandoObject are always ExpandoObjects when it gets deserialized from JSON. It recursively adds ScriptObjects for complex member types and the object itself for all other properties to the ``ScriptObject`.

Please not that my solution uses Scriban's default member renaming, where FirstName becomes first_name and so on.

score 4 · Answer 2 · answered Jul 01 '22 at 12:01

Not sure if the previous versions supported doing it, but it looks like this is more efficient, and the Scriban example (github) does this.

var json = "{\"name\":{\"first\":\"Maia\"}}";
var template = Template.Parse("Hello {{model.name.first}}");        
var result = template.Render(new { model = JsonConvert.DeserializeObject<ExpandoObject>(json) });

Console.WriteLine(result);

// Output: Hello Maia

score 2 · Answer 3 · answered Mar 30 '20 at 17:53

In cases when you have a simple object you can try something like this.

var json = "{\"Phone\":\"555000000\",\"Name\":\"Maia\"}";
var scriptObject = new Scriban.Runtime.ScriptObject();
var data = JsonConvert.DeserializeObject<ExpandoObject>(json);
foreach (var prop in data)
{
   scriptObject.Add(prop.Key, prop.Value);
}
var templateCtx = new Scriban.TemplateContext();
templateCtx.PushGlobal(scriptObject);
var template = Scriban.Template.Parse("Hello {{Name}}");
var result = template.Render(templateCtx); // result will be "Hello Maia"

Render scriban template from json data

3 Answers3