Introduce a way to filter documents with a basic syntax

meilidb-core/examples/from_file.rs

@@ -53,6 +53,11 @@ struct SearchCommand {
     #[structopt(short = "C", long, default_value = "35")]
     char_context: usize,
 
+    /// A filter string that can be `!adult` or `adult` to
+    /// filter documents on this specfied field
+    #[structopt(short, long)]
+    filter: Option<String>,
+
     /// Fields that must be displayed.
     displayed_fields: Vec<String>,
 }
@@ -269,8 +274,29 @@ fn search_command(command: SearchCommand, database: Database) -> Result<(), Box<
             Ok(query) => {
                 let start_total = Instant::now();
 
+                let documents = match command.filter {
+                    Some(ref filter) => {
+                        let filter = filter.as_str();
+                        let (positive, filter) = if filter.chars().next() == Some('!') {
+                            (false, &filter[1..])
+                        } else {
+                            (true, filter)
+                        };
+
+                        let attr = schema.attribute(&filter).expect("Could not find filtered attribute");
+
                         let builder = index.query_builder();
-                let documents = builder.query(&reader, &query, 0..command.number_results)?;
+                        let builder = builder.with_filter(|document_id| {
+                            let string: String = index.document_attribute(&reader, document_id, attr).unwrap().unwrap();
+                            (string == "true") == positive
+                        });
+                        builder.query(&reader, &query, 0..command.number_results)?
+                    },
+                    None => {
+                        let builder = index.query_builder();
+                        builder.query(&reader, &query, 0..command.number_results)?
+                    }
+                };
 
                 let mut retrieve_duration = Duration::default();
 

meilidb-core/src/serde/deserializer.rs

@@ -52,7 +52,7 @@ pub struct Deserializer<'a, R> {
     pub reader: &'a R,
     pub documents_fields: DocumentsFields,
     pub schema: &'a Schema,
-    pub fields: Option<&'a HashSet<SchemaAttr>>,
+    pub attributes: Option<&'a HashSet<SchemaAttr>>,
 }
 
 impl<'de, 'a, 'b, R: 'a> de::Deserializer<'de> for &'b mut Deserializer<'a, R>
@@ -86,7 +86,7 @@ where R: rkv::Readable,
                 };
 
                 let is_displayed = self.schema.props(attr).is_displayed();
-                if is_displayed && self.fields.map_or(true, |f| f.contains(&attr)) {
+                if is_displayed && self.attributes.map_or(true, |f| f.contains(&attr)) {
                     let attribute_name = self.schema.attribute_name(attr);
                     Some((attribute_name, Value::new(value)))
                 } else {

meilidb-core/src/store/documents_fields.rs

@@ -74,7 +74,7 @@ impl DocumentsFields {
         Ok(count)
     }
 
-    pub fn document_field<'a>(
+    pub fn document_attribute<'a>(
         &self,
         reader: &'a impl rkv::Readable,
         document_id: DocumentId,

meilidb-core/src/store/mod.rs

@@ -15,7 +15,7 @@ pub use self::updates::Updates;
 pub use self::updates_results::UpdatesResults;
 
 use std::collections::HashSet;
-use meilidb_schema::Schema;
+use meilidb_schema::{Schema, SchemaAttr};
 use serde::de;
 use crate::{update, query_builder::QueryBuilder, DocumentId, MResult, Error};
 use crate::serde::Deserializer;
@@ -69,15 +69,15 @@ impl Index {
     pub fn document<T: de::DeserializeOwned, R: rkv::Readable>(
         &self,
         reader: &R,
-        fields: Option<&HashSet<&str>>,
+        attributes: Option<&HashSet<&str>>,
         document_id: DocumentId,
     ) -> MResult<Option<T>>
     {
         let schema = self.main.schema(reader)?;
         let schema = schema.ok_or(Error::SchemaMissing)?;
 
-        let fields = match fields {
+        let attributes = match attributes {
-            Some(fields) => fields.into_iter().map(|name| schema.attribute(name)).collect(),
+            Some(attributes) => attributes.into_iter().map(|name| schema.attribute(name)).collect(),
             None => None,
         };
 
@@ -86,7 +86,7 @@ impl Index {
             reader,
             documents_fields: self.documents_fields,
             schema: &schema,
-            fields: fields.as_ref(),
+            attributes: attributes.as_ref(),
         };
 
         // TODO: currently we return an error if all document fields are missing,
@@ -94,6 +94,20 @@ impl Index {
         Ok(T::deserialize(&mut deserializer).map(Some)?)
     }
 
+    pub fn document_attribute<T: de::DeserializeOwned, R: rkv::Readable>(
+        &self,
+        reader: &R,
+        document_id: DocumentId,
+        attribute: SchemaAttr,
+    ) -> MResult<Option<T>>
+    {
+        let bytes = self.documents_fields.document_attribute(reader, document_id, attribute)?;
+        match bytes {
+            Some(bytes) => Ok(Some(rmp_serde::from_read_ref(bytes)?)),
+            None => Ok(None),
+        }
+    }
+
     pub fn schema_update(&self, mut writer: rkv::Writer, schema: Schema) -> MResult<()> {
         update::push_schema_update(&mut writer, self.updates, self.updates_results, schema)?;
         writer.commit()?;