feat: Add PropsExpr API

db/example_test.go

@@ -264,6 +264,18 @@ func ExampleProps() {
 	//   ({name: p.name})
 }
 
+func ExamplePropsExpr() {
+	var p tests.Person
+	c().
+		Create(
+			Node(Qual(&p, "p", PropsExpr("$someVar"))).
+				To(Var("e", PropsExpr("$anotherVar")), nil),
+		).
+		Print()
+	// Output:
+	// CREATE (p:Person $someVar)-[e $anotherVar]->()
+}
+
 func ExampleWhere() {
 	c().
 		Match(Node("n")).

db/var.go

@@ -106,3 +106,13 @@ func VarLength(varLengthExpr internal.Expr) internal.VariableOption {
 // - Keys behave as [pkg/github.com/rlch/neogo/client.PropertyIdentifier]'s
 // - Values behave as [pkg/github.com/rlch/neogo/client.ValueIdentifier]'s
 type Props = internal.Props
+
+// PropsExpr sets the properties of a node or relationship to the provided
+// expression.
+func PropsExpr(propsExpr internal.Expr) internal.VariableOption {
+	return &internal.Configurer{
+		Variable: func(v *internal.Variable) {
+			v.PropsExpr = propsExpr
+		},
+	}
+}

internal/cypher.go

@@ -41,6 +41,7 @@ var (
 	errWhereReturnSubclause   = errors.New("WHERE clause in RETURN sub-clause is not allowed")
 	errInvalidPropExpr        = errors.New("invalid property expression. Property expressions must be strings or an identifier")
 	errSubqueryImportAlias    = errors.New("aliasing or expressions are not supported in importing WITH clauses")
+	errUnresolvedProps        = errors.New("resolving from multiple properties is not allowed")
 )
 
 func (s *cypher) catch(op func()) {
@@ -88,17 +89,33 @@ func (cy *cypher) writeNode(m *member) {
 				padProps = true
 				fmt.Fprintf(cy, ":%s", strings.Join(nodeLabels, ":"))
 			}
-			if m.variable != nil && m.variable.Props != nil {
-				if padProps {
-					cy.WriteRune(' ')
+			var resolvedProps int
+			if m.variable != nil {
+				if m.variable.Props != nil {
+					resolvedProps++
+					if padProps {
+						cy.WriteRune(' ')
+					}
+					cy.writeProps(m.variable.Props)
 				}
-				cy.writeProps(m.variable.Props)
-			} else if m.props != "" {
+				if m.variable.PropsExpr != "" {
+					resolvedProps++
+					if padProps {
+						cy.WriteRune(' ')
+					}
+					cy.WriteString(string(m.variable.PropsExpr))
+				}
+			}
+			if m.props != "" {
+				resolvedProps++
 				if padProps {
 					cy.WriteRune(' ')
 				}
 				cy.WriteString(m.props)
 			}
+			if resolvedProps > 1 {
+				panic(errUnresolvedProps)
+			}
 			if m.where != nil {
 				cy.WriteRune(' ')
 				m.where.Identifier = m.identifier
@@ -142,13 +159,26 @@ func (cy *cypher) writeRelationship(m *member, rs *relationshipPattern) {
 			if m.variable != nil && m.variable.VarLength != "" {
 				inner = inner + string(m.variable.VarLength)
 			}
-			if m.variable != nil && m.variable.Props != nil {
-				inner = inner + " " + cy.writeToString(func(cy *cypher) {
-					cy.writeProps(m.variable.Props)
-				})
-			} else if m.props != "" {
+			var resolvedProps int
+			if m.variable != nil {
+				if m.variable.Props != nil {
+					resolvedProps++
+					inner = inner + " " + cy.writeToString(func(cy *cypher) {
+						cy.writeProps(m.variable.Props)
+					})
+				}
+				if m.variable.PropsExpr != "" {
+					resolvedProps++
+					inner = inner + " " + string(m.variable.PropsExpr)
+				}
+			}
+			if m.props != "" {
+				resolvedProps++
 				inner = inner + " " + m.props
 			}
+			if resolvedProps > 1 {
+				panic(errUnresolvedProps)
+			}
 			if m.where != nil {
 				m.where.Identifier = m.identifier
 				prevBuilder := cy.Builder

internal/option.go

@@ -17,7 +17,7 @@ func ConfigureWhere(w *Where, configurer WhereOption) {
 }
 
 type Configurer struct {
-	Merge   func(*Merge)
+	Merge          func(*Merge)
 	Variable       func(*Variable)
 	ProjectionBody func(*ProjectionBody)
 	Where          func(*Where)
@@ -68,6 +68,7 @@ type (
 		Expr      Expr
 		Where     *Where
 		Props     Props
+		PropsExpr Expr
 		Pattern   Expr
 		VarLength Expr
 	}

internal/scope.go

@@ -203,6 +203,9 @@ func (s *Scope) unfoldIdentifier(value any) (
 		if variable.VarLength == "" {
 			variable.VarLength = v.VarLength
 		}
+		if variable.PropsExpr == "" {
+			variable.PropsExpr = v.PropsExpr
+		}
 	}
 RecurseToEntity:
 	for {