Template rendering

crates/meilisearch/src/routes/indexes/render.rs

@@ -13,6 +13,7 @@ use meilisearch_types::error::ResponseError;
 use meilisearch_types::error::{Code};
 use meilisearch_types::index_uid::IndexUid;
 use meilisearch_types::keys::actions;
+use meilisearch_types::milli::vector::json_template::{self, JsonTemplate};
 use meilisearch_types::serde_cs::vec::CS;
 use meilisearch_types::{heed, milli, Index};
 use serde::Serialize;
@@ -165,6 +166,8 @@ enum RenderError {
 
     DocumentNotFound(String),
     BothInlineDocAndDocId,
+    TemplateParsing(json_template::Error),
+    TemplateRendering(json_template::Error),
 }
 
 impl From<heed::Error> for RenderError {
@@ -282,6 +285,14 @@ impl From<RenderError> for ResponseError {
                 String::from("A document id was provided but adding it to the input would overwrite the `doc` field that you already defined inline."),
                 Code::InvalidRenderInput,
             ),
+            TemplateParsing(err) => ResponseError::from_msg(
+                format!("Error parsing template: {}", err.parsing_error("input")),
+                Code::InvalidRenderTemplate,
+            ),
+            TemplateRendering(err) => ResponseError::from_msg(
+                format!("Error rendering template: {}", err.rendering_error("input")),
+                Code::InvalidRenderTemplate,
+            ),
         }
     }
 }
@@ -438,7 +449,14 @@ async fn render(index: Index, query: RenderQuery) -> Result<RenderResult, Render
         }
     }
 
-    Ok(RenderResult { template, rendered: String::from("TODO: Implement render logic here") })
+    let json_template = JsonTemplate::new(template.clone())
+        .map_err(TemplateParsing)?;
+    
+    let rendered = json_template
+        .render_serializable(&media)
+        .map_err(TemplateRendering)?;
+
+    Ok(RenderResult { template, rendered })
 }
 
 #[derive(Debug, Clone, PartialEq, Deserr, ToSchema)]
@@ -471,5 +489,5 @@ pub struct RenderQueryInput {
 #[derive(Debug, Clone, Serialize, PartialEq, ToSchema)]
 pub struct RenderResult {
     template: serde_json::Value,
-    rendered: String,
+    rendered: serde_json::Value,
 }

crates/milli/src/vector/json_template/mod.rs

@@ -14,7 +14,8 @@
 #![warn(missing_docs)]
 
 use bumpalo::Bump;
-use liquid::{Parser, Template};
+use liquid::{Object, Parser, Template};
+use serde::Serialize;
 use serde_json::{Map, Value};
 
 use crate::prompt::ParseableDocument;
@@ -61,21 +62,35 @@ pub struct Error {
 impl Error {
     /// Produces an error message when the error happened at rendering time.
     pub fn rendering_error(&self, root: &str) -> String {
+        if self.path.is_empty() {
+            format!(
+                "error while rendering template: {}",
+                &self.template_error
+            )
+        } else {
             format!(
                 "in `{}`, error while rendering template: {}",
                 path_with_root(root, self.path.iter()),
                 &self.template_error
             )
         }
+    }
 
     /// Produces an error message when the error happened at parsing time.
-    pub fn parsing(&self, root: &str) -> String {
+    pub fn parsing_error(&self, root: &str) -> String {
+        if self.path.is_empty() {
+            format!(
+                "error while parsing template: {}",
+                &self.template_error
+            )
+        } else {
             format!(
                 "in `{}`, error while parsing template: {}",
                 path_with_root(root, self.path.iter()),
                 &self.template_error
             )
         }
+    }
 }
 
 impl JsonTemplate {
@@ -134,6 +149,17 @@ impl JsonTemplate {
         self.render(&search_data)
     }
 
+    /// Renders any serializable value by converting it to a liquid object and rendering it with the template.
+    /// If its a map, values inside can be accessed directly by their keys.
+    pub fn render_serializable<T: Serialize>(&self, object: &T) -> Result<Value, Error> {
+        let object = liquid::to_object(object)
+            .map_err(|err| Error {
+                template_error: err,
+                path: ValuePath::new(),
+            })?;
+        self.render(&object)
+    }
+
     /// The JSON value representing the underlying template
     pub fn template(&self) -> &Value {
         &self.value

crates/milli/src/vector/rest.rs

@@ -113,7 +113,7 @@ impl RequestData {
             for (name, value) in indexing_fragments {
                 JsonTemplate::new(value).map_err(|error| {
                     NewEmbedderError::rest_could_not_parse_template(
-                        error.parsing(&format!(".indexingFragments.{name}")),
+                        error.parsing_error(&format!(".indexingFragments.{name}")),
                     )
                 })?;
             }
@@ -623,7 +623,7 @@ impl RequestFromFragments {
             .map(|(name, value)| {
                 let json_template = JsonTemplate::new(value).map_err(|error| {
                     NewEmbedderError::rest_could_not_parse_template(
-                        error.parsing(&format!(".searchFragments.{name}")),
+                        error.parsing_error(&format!(".searchFragments.{name}")),
                     )
                 })?;
                 Ok((name, json_template))