feat: null and undefined values in arguments and empty input objects and lists in filters

CHANGELOG.md

@@ -9,8 +9,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Support for filtering by `null` values
+
 ### Changed
 
+- Improved handling of `null` and `undefined` values in query arguments
+- Empty filter lists resolve to `false` and empty filter objects resolve to `true`
+
 ### Fixed
 
 - Handling of GraphQL queries that are sent via `GET` requests using the `query` URL parameter if GraphiQL is enabled

lib/resolvers/crud/read.js

@@ -11,7 +11,10 @@ module.exports = async (service, entity, selection) => {
   query.columns(astToColumns(selection.selectionSet.selections))
 
   const filter = getArgumentByName(args, ARGS.filter)
-  if (filter) query.where(astToWhere(filter))
+  if (filter) {
+    const where = astToWhere(filter)
+    if (where) query.where(where)
+  }
 
   const orderBy = getArgumentByName(args, ARGS.orderBy)
   if (orderBy) query.orderBy(astToOrderBy(orderBy))

lib/resolvers/parse/ast/enrich.js

@@ -23,11 +23,13 @@ const _traverseListValue = (info, listValue, _fields) => {
   }
 }
 
+const _isScalarKind = kind => kind === Kind.INT || kind === Kind.FLOAT || kind === Kind.STRING || kind === Kind.BOOLEAN
+
 const _traverseArgumentOrObjectField = (info, argumentOrObjectField, _fieldOr_arg) => {
   const value = argumentOrObjectField.value
 
   const type = _getTypeFrom_fieldOr_arg(_fieldOr_arg)
-  if (type.parseLiteral && value.kind !== Kind.VARIABLE) value.value = type.parseLiteral(value)
+  if (_isScalarKind(value.kind)) value.value = type.parseLiteral(value)
 
   switch (value.kind) {
     case Kind.VARIABLE:
@@ -40,6 +42,9 @@ const _traverseArgumentOrObjectField = (info, argumentOrObjectField, _fieldOr_ar
       _traverseObjectValue(info, value, type.getFields())
       break
   }
+
+  // Convenience value for both literal and variable values
+  if (argumentOrObjectField.value?.kind === Kind.NULL) argumentOrObjectField.value.value = null
 }
 
 const _traverseSelectionSet = (info, selectionSet, _fields) => {

lib/resolvers/parse/ast/fromObject.js

@@ -1,6 +1,8 @@
 const { Kind } = require('graphql')
 const { isPlainObject } = require('./util')
 
+const _nullValue = { kind: Kind.NULL }
+
 const _valueToGenericScalarValue = value => ({
   kind: 'GenericScalarValue',
   value
@@ -32,6 +34,10 @@ const _variableToValue = variable => {
     return _arrayToListValue(variable)
   } else if (isPlainObject(variable)) {
     return _objectToObjectValue(variable)
+  } else if (variable === null) {
+    return _nullValue
+  } else if (variable === undefined) {
+    return undefined
   }
   return _valueToGenericScalarValue(variable)
 }

lib/resolvers/parse/ast2cqn/utils/index.js

@@ -1,3 +1,6 @@
-const getArgumentByName = (args, name) => args.find(arg => arg.name.value === name)
+const { Kind } = require('graphql')
+
+const getArgumentByName = (args, name) =>
+  args.find(arg => arg.value && arg.name.value === name && arg.value.kind !== Kind.NULL)
 
 module.exports = { getArgumentByName }

lib/resolvers/parse/ast2cqn/where.js

@@ -32,6 +32,8 @@ const _objectFieldTo_xpr = (objectField, columnName) => {
 }
 
 const _parseObjectField = (objectField, columnName) => {
+  if (columnName) return _objectFieldTo_xpr(objectField, columnName)
+
   const value = objectField.value
   const name = objectField.name.value
   switch (value.kind) {
@@ -40,22 +42,31 @@ const _parseObjectField = (objectField, columnName) => {
     case Kind.OBJECT:
       return _parseObjectValue(value, name)
   }
-  return _objectFieldTo_xpr(objectField, columnName)
 }
 
 const _arrayInsertBetweenFlat = (array, element) =>
   array.flatMap((e, index) => (index === array.length - 1 ? [e] : [e, element])).flat()
 
 const _joinedXprFrom_xprs = (_xprs, operator) => ({ xpr: _arrayInsertBetweenFlat(_xprs, operator) })
 
+const _true_xpr = [{ val: 1 }, '=', { val: 1 }]
+
 const _parseObjectValue = (objectValue, columnName) => {
-  const _xprs = objectValue.fields.map(field => _parseObjectField(field, columnName))
-  return _xprs.length === 1 ? _xprs[0] : _joinedXprFrom_xprs(_xprs, 'and')
+  const _xprs = objectValue.fields
+    .map(field => _parseObjectField(field, columnName))
+    .filter(field => field !== undefined)
+  if (_xprs.length === 0) return _true_xpr
+  else if (_xprs.length === 1) return _xprs[0]
+  return _joinedXprFrom_xprs(_xprs, 'and')
 }
 
+const _false_xpr = [{ val: 0 }, '=', { val: 1 }]
+
 const _parseListValue = (listValue, columnName) => {
-  const _xprs = listValue.values.map(value => _parseObjectValue(value, columnName))
-  return _xprs.length === 1 ? _xprs[0] : _joinedXprFrom_xprs(_xprs, 'or')
+  const _xprs = listValue.values.map(value => _parseObjectValue(value, columnName)).filter(value => value !== undefined)
+  if (_xprs.length === 0) return _false_xpr
+  else if (_xprs.length === 1) return _xprs[0]
+  return _joinedXprFrom_xprs(_xprs, 'or')
 }
 
 const astToWhere = filterArg => {