Support setting array columns to empty array instead of setting those to null

changelog.md

@@ -8,6 +8,8 @@
 
 ### Fixed
 
+- Fixed array column updates to properly handle empty arrays instead of incorrectly setting them to null.
+
 ## [v2.1.1] - 2025-03-12
 
 ### Changed

crates/query-engine/translation/src/translation/query/values.rs

@@ -155,11 +155,26 @@ pub(crate) fn translate_projected(
             let converted_element_exp =
                 translate_projected(env, state, type_name, element_expression)?;
 
+            // Create an empty array of the correct type to use as the default value
+            let empty_array = sql::ast::Expression::Cast {
+                expression: Box::new(sql::ast::Expression::Value(sql::ast::Value::Array(vec![]))),
+                r#type: sql::ast::ScalarType::ArrayType(type_to_ast_scalar_type_name(
+                    env, type_name,
+                )?),
+            };
+
             let mut result_select = sql::helpers::simple_select(vec![(
                 element_column,
+                // Use COALESCE to return an empty array instead of NULL when array_agg returns NULL
                 sql::ast::Expression::FunctionCall {
-                    function: sql::ast::Function::Unknown("array_agg".to_string()),
-                    args: vec![converted_element_exp],
+                    function: sql::ast::Function::Coalesce,
+                    args: vec![
+                        sql::ast::Expression::FunctionCall {
+                            function: sql::ast::Function::Unknown("array_agg".to_string()),
+                            args: vec![converted_element_exp],
+                        },
+                        empty_array,
+                    ],
                 },
             )]);
 

crates/query-engine/translation/tests/goldenfiles/mutations/v2_update_array_column_empty/configuration.json

@@ -0,0 +1,121 @@
+{
+  "version": "5",
+  "$schema": "../../../../../../../static/configuration.schema.json",
+  "connectionSettings": {
+    "connectionUri": {
+      "variable": "CONNECTION_URI"
+    },
+    "poolSettings": {
+      "maxConnections": 50,
+      "poolTimeout": 30,
+      "idleTimeout": 180,
+      "checkConnectionAfterIdle": 60,
+      "connectionLifetime": 600
+    },
+    "isolationLevel": "ReadCommitted"
+  },
+  "metadata": {
+    "tables": {
+      "items": {
+        "schemaName": "public",
+        "tableName": "items",
+        "columns": {
+          "id": {
+            "name": "id",
+            "type": {
+              "scalarType": "int4"
+            },
+            "nullable": "nonNullable",
+            "description": null
+          },
+          "name": {
+            "name": "name",
+            "type": {
+              "scalarType": "text"
+            },
+            "nullable": "nullable",
+            "description": null
+          },
+          "tags": {
+            "name": "tags",
+            "type": {
+              "arrayType": {
+                "scalarType": "text"
+              }
+            },
+            "nullable": "nullable",
+            "description": null
+          }
+        },
+        "uniquenessConstraints": {
+          "items_pkey": ["id"]
+        },
+        "foreignRelations": {},
+        "description": null
+      }
+    },
+    "types": {
+      "scalar": {
+        "int4": {
+          "typeName": "int4",
+          "schemaName": "pg_catalog",
+          "description": null,
+          "aggregateFunctions": {},
+          "comparisonOperators": {},
+          "typeRepresentation": "int32"
+        },
+        "text": {
+          "typeName": "text",
+          "schemaName": "pg_catalog",
+          "description": null,
+          "aggregateFunctions": {},
+          "comparisonOperators": {},
+          "typeRepresentation": "string"
+        }
+      },
+      "composite": {}
+    },
+    "nativeOperations": {
+      "queries": {},
+      "mutations": {}
+    }
+  },
+  "introspectionOptions": {
+    "excludedSchemas": [
+      "information_schema",
+      "pg_catalog",
+      "tiger",
+      "crdb_internal",
+      "columnar",
+      "columnar_internal"
+    ],
+    "unqualifiedSchemasForTables": ["public"],
+    "unqualifiedSchemasForTypesAndProcedures": [
+      "public",
+      "pg_catalog",
+      "tiger"
+    ],
+    "typeRepresentations": {
+      "bit": "string",
+      "bool": "boolean",
+      "bpchar": "string",
+      "char": "string",
+      "date": "date",
+      "float4": "float32",
+      "float8": "float64",
+      "int2": "int16",
+      "int4": "int32",
+      "int8": "int64AsString",
+      "numeric": "bigDecimalAsString",
+      "text": "string",
+      "time": "time",
+      "timestamp": "timestamp",
+      "timestamptz": "timestamptz",
+      "timetz": "timetz",
+      "uuid": "uUID",
+      "varchar": "string"
+    }
+  },
+  "mutationsVersion": "v2",
+  "mutationsPrefix": null
+}

crates/query-engine/translation/tests/goldenfiles/mutations/v2_update_array_column_empty/request.json

@@ -0,0 +1,47 @@
+{
+  "$schema": "../../../../../../../static/mutation.schema.json",
+  "operations": [
+    {
+      "type": "procedure",
+      "name": "v2_update_items_by_id",
+      "arguments": {
+        "key_id": 1,
+        "update_columns": {
+          "tags": {
+            "_set": []
+          }
+        }
+      },
+      "fields": {
+        "type": "object",
+        "fields": {
+          "affected_rows": {
+            "type": "column",
+            "column": "affected_rows"
+          },
+          "returning": {
+            "type": "column",
+            "column": "returning",
+            "fields": {
+              "type": "array",
+              "fields": {
+                "type": "object",
+                "fields": {
+                  "id": {
+                    "type": "column",
+                    "column": "id"
+                  },
+                  "tags": {
+                    "type": "column",
+                    "column": "tags"
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  ],
+  "collection_relationships": {}
+}

crates/query-engine/translation/tests/goldenfiles/mutations/v2_update_array_column_null/configuration.json

@@ -0,0 +1,121 @@
+{
+  "version": "5",
+  "$schema": "../../../../../../../static/configuration.schema.json",
+  "connectionSettings": {
+    "connectionUri": {
+      "variable": "CONNECTION_URI"
+    },
+    "poolSettings": {
+      "maxConnections": 50,
+      "poolTimeout": 30,
+      "idleTimeout": 180,
+      "checkConnectionAfterIdle": 60,
+      "connectionLifetime": 600
+    },
+    "isolationLevel": "ReadCommitted"
+  },
+  "metadata": {
+    "tables": {
+      "items": {
+        "schemaName": "public",
+        "tableName": "items",
+        "columns": {
+          "id": {
+            "name": "id",
+            "type": {
+              "scalarType": "int4"
+            },
+            "nullable": "nonNullable",
+            "description": null
+          },
+          "name": {
+            "name": "name",
+            "type": {
+              "scalarType": "text"
+            },
+            "nullable": "nullable",
+            "description": null
+          },
+          "tags": {
+            "name": "tags",
+            "type": {
+              "arrayType": {
+                "scalarType": "text"
+              }
+            },
+            "nullable": "nullable",
+            "description": null
+          }
+        },
+        "uniquenessConstraints": {
+          "items_pkey": ["id"]
+        },
+        "foreignRelations": {},
+        "description": null
+      }
+    },
+    "types": {
+      "scalar": {
+        "int4": {
+          "typeName": "int4",
+          "schemaName": "pg_catalog",
+          "description": null,
+          "aggregateFunctions": {},
+          "comparisonOperators": {},
+          "typeRepresentation": "int32"
+        },
+        "text": {
+          "typeName": "text",
+          "schemaName": "pg_catalog",
+          "description": null,
+          "aggregateFunctions": {},
+          "comparisonOperators": {},
+          "typeRepresentation": "string"
+        }
+      },
+      "composite": {}
+    },
+    "nativeOperations": {
+      "queries": {},
+      "mutations": {}
+    }
+  },
+  "introspectionOptions": {
+    "excludedSchemas": [
+      "information_schema",
+      "pg_catalog",
+      "tiger",
+      "crdb_internal",
+      "columnar",
+      "columnar_internal"
+    ],
+    "unqualifiedSchemasForTables": ["public"],
+    "unqualifiedSchemasForTypesAndProcedures": [
+      "public",
+      "pg_catalog",
+      "tiger"
+    ],
+    "typeRepresentations": {
+      "bit": "string",
+      "bool": "boolean",
+      "bpchar": "string",
+      "char": "string",
+      "date": "date",
+      "float4": "float32",
+      "float8": "float64",
+      "int2": "int16",
+      "int4": "int32",
+      "int8": "int64AsString",
+      "numeric": "bigDecimalAsString",
+      "text": "string",
+      "time": "time",
+      "timestamp": "timestamp",
+      "timestamptz": "timestamptz",
+      "timetz": "timetz",
+      "uuid": "uUID",
+      "varchar": "string"
+    }
+  },
+  "mutationsVersion": "v2",
+  "mutationsPrefix": null
+}

crates/query-engine/translation/tests/goldenfiles/mutations/v2_update_array_column_null/request.json

@@ -0,0 +1,47 @@
+{
+  "$schema": "../../../../../../../static/mutation.schema.json",
+  "operations": [
+    {
+      "type": "procedure",
+      "name": "v2_update_items_by_id",
+      "arguments": {
+        "key_id": 1,
+        "update_columns": {
+          "tags": {
+            "_set": null
+          }
+        }
+      },
+      "fields": {
+        "type": "object",
+        "fields": {
+          "affected_rows": {
+            "type": "column",
+            "column": "affected_rows"
+          },
+          "returning": {
+            "type": "column",
+            "column": "returning",
+            "fields": {
+              "type": "array",
+              "fields": {
+                "type": "object",
+                "fields": {
+                  "id": {
+                    "type": "column",
+                    "column": "id"
+                  },
+                  "tags": {
+                    "type": "column",
+                    "column": "tags"
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  ],
+  "collection_relationships": {}
+}