Added 'build_with_params' function the visitor trait

CHANGELOG.md

@@ -2,6 +2,7 @@
 ## Unreleased
 
 - Added support for `ROW_TO_JSON` function in postgresql
+- Added `build_with_params` function the `Visitor` trait
 
 ## v0.2.0-alpha.13
 

src/visitor.rs

@@ -65,6 +65,13 @@ pub trait Visitor<'a> {
     where
         Q: Into<Query<'a>>;
 
+    /// Behave exactly like [build](Visitor::build) but takes a vector of `Value<'a>` as arguments.
+    /// The next arguments to be inserted into the query will be **appended**, allowing to
+    /// build more complex queries.
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>;
+
     /// Write to the query.
     fn write<D: fmt::Display>(&mut self, s: D) -> Result;
 

src/visitor/mssql.rs

@@ -128,17 +128,26 @@ impl<'a> Visitor<'a> for Mssql<'a> {
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
     where
-        Q: Into<crate::ast::Query<'a>>,
+        Q: Into<Query<'a>>,
     {
-        let mut this = Mssql {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let mut mssql = Mssql {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
             order_by_set: false,
         };
 
-        Mssql::visit_query(&mut this, query.into())?;
+        Mssql::visit_query(&mut mssql, query.into())?;
 
-        Ok((this.query, this.parameters))
+        Ok((mssql.query, mssql.parameters))
     }
 
     fn write<D: std::fmt::Display>(&mut self, s: D) -> visitor::Result {

src/visitor/mysql.rs

@@ -38,12 +38,21 @@ impl<'a> Visitor<'a> for Mysql<'a> {
     const C_WILDCARD: &'static str = "%";
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
     where
         Q: Into<Query<'a>>,
     {
         let mut mysql = Mysql {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
         };
 
         Mysql::visit_query(&mut mysql, query.into())?;

src/visitor/postgres.rs

@@ -20,12 +20,21 @@ impl<'a> Visitor<'a> for Postgres<'a> {
     const C_WILDCARD: &'static str = "%";
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
     where
         Q: Into<Query<'a>>,
     {
         let mut postgres = Postgres {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
         };
 
         Postgres::visit_query(&mut postgres, query.into())?;

src/visitor/sqlite.rs

@@ -22,12 +22,21 @@ impl<'a> Visitor<'a> for Sqlite<'a> {
     const C_WILDCARD: &'static str = "%";
 
     fn build<Q>(query: Q) -> crate::Result<(String, Vec<Value<'a>>)>
+    where
+        Q: Into<Query<'a>>,
+    {
+        let params: Vec<Value<'a>> = Vec::with_capacity(128);
+
+        Self::build_with_params(query, params)
+    }
+
+    fn build_with_params<Q>(query: Q, existing_params: Vec<Value<'a>>) -> crate::Result<(String, Vec<Value<'a>>)>
     where
         Q: Into<Query<'a>>,
     {
         let mut sqlite = Sqlite {
             query: String::with_capacity(4096),
-            parameters: Vec::with_capacity(128),
+            parameters: existing_params,
         };
 
         Sqlite::visit_query(&mut sqlite, query.into())?;