WIP query

README.md

@@ -51,6 +51,18 @@ To try out the demo code in this repository, follow these steps:
    (i.e. the file `test/test.g.dart`) and is necessary each time you add or change a class annotated with `@Entity(...)`.
 4. Finally run `pub run test` to run the unit tests.
 
+Mac OS signed dart binary issue
+-------------------------------
+
+If dart complains that it cannot find the `libobjectbox.dylib`, after you've installed by following step 1,
+then you probably have to unsign the dart binary:
+
+```bash
+sudo xcode --remove-signature `which dart`
+``` 
+
+source: [dart issue](https://github.com/dart-lang/sdk/issues/38314#issuecomment-534102841)
+
 Dart integration
 ----------------
 In general, Dart class annotations are used to mark classes as ObjectBox entities and provide meta information.
@@ -98,6 +110,40 @@ print("refetched note: ${box.get(note.id)}");
 store.close();
 ```
 
+Query and QueryBuilder
+----------------------
+
+Basic querying can be done with e.g.:
+
+```dart
+// var store ...
+// var box ...
+
+box.putMany([Note(), Note(), Note()]);
+box.put(Note.construct("Hello world!"));
+
+final queryNullText = box.query(Note_.text.isNull()).build();
+
+assert (queryNullText.count() == 3);
+
+queryNullText.close(); // We have to manually close queries and query builders.
+```
+
+More complex queries can be constructed using `and/or` operators.
+Also there is basic operator overloading support for `equal`, `greater`, `less`, `and` and `or`,
+respectively `==`, `>`, `<`, `&`, `|`.
+
+```dart
+// final box ...
+
+box.query(text.equal("meh").or(text.equal("bleh")).or(text.contains("Hello"))).build();
+
+// equivalent to
+
+final overloaded = ((text == "meh") | (text == "bleh")) | text.contains("Hello");
+box.query(overloaded as Condition).build(); // the cast is necessary due to the type analyzer
+```
+
 Basic technical approach
 ------------------------
 ObjectBox offers a [C API](https://github.com/objectbox/objectbox-c) which can be called by [Dart FFI](https://dart.dev/server/c-interop).

bin/objectbox_model_generator/lib/src/code_chunks.dart

@@ -1,4 +1,7 @@
 import "package:objectbox/src/modelinfo/index.dart";
+import "package:analyzer/dart/element/element.dart";
+import "package:objectbox/src/bindings/constants.dart" show OBXPropertyType;
+import "package:source_gen/source_gen.dart" show InvalidGenerationSourceError;
 
 class CodeChunks {
   static String modelInfoLoader() => """
@@ -43,4 +46,56 @@ class CodeChunks {
         const ${name}_OBXDefs = EntityDefinition<${name}>(_${name}_OBXModelGetter, _${name}_OBXReader, _${name}_OBXBuilder);
       """;
   }
+
+  static String _queryConditionBuilder(ModelEntity readEntity) {
+    final ret = <String>[];
+    for (var f in readEntity.properties) {
+
+      final name = f.name;
+
+      // see OBXPropertyType
+      String fieldType;
+      switch(f.type) {
+        case OBXPropertyType.Bool:
+          fieldType = "Boolean";
+          break;
+        case OBXPropertyType.String:
+          fieldType = "String";
+          break;
+        float:
+        case OBXPropertyType.Double:
+          fieldType = "Double";
+          break;
+        case OBXPropertyType.Float:
+          continue float;
+        integer:
+        case OBXPropertyType.Int:
+          fieldType = "Integer";
+          break;
+        case OBXPropertyType.Byte:
+          continue integer;
+        case OBXPropertyType.Short:
+          continue integer;
+        case OBXPropertyType.Char:
+          continue integer;
+        case OBXPropertyType.Long:
+          continue integer;
+        default:
+          throw InvalidGenerationSourceError("Unsupported property type (${f.type}): ${readEntity.name}.${name}");
+      }
+
+      ret.add("""
+        static final ${name} = Query${fieldType}Property(entityId:${readEntity.id.id}, propertyId:${f.id.id}, obxType:${f.type});
+        """);
+    }
+    return ret.join();
+  }
+
+  static String queryConditionClasses(ModelEntity readEntity) {
+    // TODO add entity.id check to throw an error Box if the wrong entity.property is used
+    return """
+    class ${readEntity.name}_ {
+      ${_queryConditionBuilder(readEntity)}
+    }""";
+  }
 }

bin/objectbox_model_generator/lib/src/generator.dart

@@ -6,6 +6,7 @@ import "package:build/src/builder/build_step.dart";
 import "package:source_gen/source_gen.dart";
 
 import "package:objectbox/objectbox.dart" as obx;
+import "package:objectbox/src/annotations.dart";
 import "package:objectbox/src/bindings/constants.dart";
 
 import "code_chunks.dart";
@@ -25,6 +26,9 @@ class EntityGenerator extends GeneratorForAnnotation<obx.Entity> {
     return ModelInfo.fromMap(json.decode(await (File(ALL_MODELS_JSON).readAsString())));
   }
 
+  final _propertyChecker = const TypeChecker.fromRuntime(Property);
+  final _idChecker       = const TypeChecker.fromRuntime(Id);
+
   @override
   Future<String> generateForAnnotatedElement(
       Element elementBare, ConstantReader annotation, BuildStep buildStep) async {
@@ -56,49 +60,44 @@ class EntityGenerator extends GeneratorForAnnotation<obx.Entity> {
         int fieldType, flags = 0;
         int propUid;
 
-        if (f.metadata != null && f.metadata.length == 1) {
-          var annotElmt = f.metadata[0].element as ConstructorElement;
-          var annotType = annotElmt.returnType.toString();
-          var annotVal = f.metadata[0].computeConstantValue();
-          var fieldTypeAnnot; // for the future, with custom type sizes allowed: annotVal.getField("type");
-          fieldType = fieldTypeAnnot?.toIntValue();
-          propUid = annotVal.getField("uid").toIntValue();
-
-          // find property flags
-          if (annotType == "Id") {
-            if (hasIdProperty) {
-              throw InvalidGenerationSourceError(
-                  "in target ${elementBare.name}: has more than one properties annotated with @Id");
-            }
-            if (fieldType != null) {
-              throw InvalidGenerationSourceError(
-                  "in target ${elementBare.name}: programming error: @Id property may not specify a type");
-            }
-            if (f.type.toString() != "int") {
-              throw InvalidGenerationSourceError(
-                  "in target ${elementBare.name}: field with @Id property has type '${f.type.toString()}', but it must be 'int'");
-            }
-
-            fieldType = OBXPropertyType.Long;
-            flags |= OBXPropertyFlag.ID;
-            hasIdProperty = true;
-          } else if (annotType == "Property") {
-            // nothing special
-          } else {
-            // skip unknown annotations
-            print(
-                "warning: skipping field '${f.name}' in entity '${element.name}', as it has the unknown annotation type '$annotType'");
-            continue;
+        if (_idChecker.hasAnnotationOfExact(f)) {
+          if (hasIdProperty) {
+            throw InvalidGenerationSourceError(
+                "in target ${elementBare.name}: has more than one properties annotated with @Id");
           }
+          if (f.type.toString() != "int")
+            throw InvalidGenerationSourceError(
+                "in target ${elementBare.name}: field with @Id property has type '${f.type.toString()}', but it must be 'int'");
+
+          hasIdProperty = true;
+
+          fieldType = OBXPropertyType.Long;
+          flags |= OBXPropertyFlag.ID;
+
+          final _idAnnotation = _idChecker.firstAnnotationOfExact(f);
+          propUid = _idAnnotation.getField('uid').toIntValue();
+        }else if (_propertyChecker.hasAnnotationOfExact(f)) {
+          final _propertyAnnotation = _propertyChecker.firstAnnotationOfExact(f);
+          propUid = _propertyAnnotation.getField('uid').toIntValue();
+          fieldType = _propertyAnnotation.getField('type').toIntValue();
+          flags = _propertyAnnotation.getField('flag').toIntValue() ?? 0;
+
+          print ("annotated property found on ${f.name} with parameters: propUid(${propUid}) fieldType(${fieldType}) flags(${flags})");
+        }else {
+          print ("property found on ${f.name} with parameters: propUid(${propUid}) fieldType(${fieldType}) flags(${flags})");
         }
 
         if (fieldType == null) {
           var fieldTypeStr = f.type.toString();
-          if (fieldTypeStr == "int") {
-            fieldType = OBXPropertyType.Int;
-          } else if (fieldTypeStr == "String") {
+          if (fieldTypeStr == "int") // dart: 8 bytes
+            fieldType = OBXPropertyType.Long; // ob: 8 bytes
+          else if (fieldTypeStr == "String")
             fieldType = OBXPropertyType.String;
-          } else {
+          else if (fieldTypeStr == "bool") // 1 byte
+            fieldType = OBXPropertyType.Bool; // 1 byte
+          else if (fieldTypeStr == "double") // dart: 8 bytes
+            fieldType = OBXPropertyType.Double; // ob: 8 bytes
+          else {
             print(
                 "warning: skipping field '${f.name}' in entity '${element.name}', as it has the unsupported type '$fieldTypeStr'");
             continue;
@@ -125,6 +124,9 @@ class EntityGenerator extends GeneratorForAnnotation<obx.Entity> {
       // main code for instance builders and readers
       ret += CodeChunks.instanceBuildersReaders(readEntity);
 
+      // for building queries
+      ret += CodeChunks.queryConditionClasses(readEntity);
+
       return ret;
     } catch (e, s) {
       print(s);

lib/objectbox.dart

@@ -9,3 +9,4 @@ export "src/model.dart";
 export "src/store.dart";
 export "src/box.dart";
 export "src/modelinfo/index.dart";
+export "src/query/index.dart";

lib/src/annotations.dart

@@ -3,9 +3,19 @@ class Entity {
   const Entity({this.uid});
 }
 
+/**
+ * A dart int value can map to different OBXPropertyTypes,
+ * e.g. Short (Int16), Int (Int32), Long (Int64), all signed values.
+ * Also a dart double can also map to e.g. Float and Double
+ *
+ * Property allows the mapping to be specific. The defaults are
+ * e.g. Int -> Int64, double -> Float64, bool -> Bool.
+ *
+ * Use OBXPropertyType and OBXPropertyFlag values, resp. for type and flag.
+ */
 class Property {
-  final int uid;
-  const Property({this.uid});
+  final int uid, type, flag;
+  const Property({this.type = null, this.flag = null, this.uid = null});
 }
 
 class Id {