Resolve "isNan/whenNan formulas"

backend/src/baserow/contrib/database/formula/ast/function_defs.py

@@ -1,6 +1,6 @@
 from abc import ABC
 from decimal import Decimal
-from typing import List, Optional, Type
+from typing import List, Optional, Type, Union
 
 from django.contrib.postgres.aggregates import JSONBAgg
 from django.db.models import (
@@ -147,6 +147,8 @@ def register_formula_functions(registry):
     registry.register(BaserowCeil())
     registry.register(BaserowFloor())
     registry.register(BaserowSign())
+    registry.register(BaserowIsNaN())
+    registry.register(BaserowWhenNan())
     # Boolean functions
     registry.register(BaserowIf())
     registry.register(BaserowEqual())
@@ -769,6 +771,44 @@ def int_like_numeric_output_field() -> fields.DecimalField:
     )
 
 
+class BaserowIsNaN(OneArgumentBaserowFunction):
+    type = "is_nan"
+    arg_type = [BaserowFormulaNumberType]
+
+    def type_function(
+        self,
+        func_call: BaserowFunctionCall[UnTyped],
+        arg: Union[BaserowExpression[BaserowFormulaNumberType]],
+    ) -> BaserowExpression[BaserowFormulaType]:
+        return func_call.with_valid_type(BaserowFormulaBooleanType())
+
+    def to_django_expression(self, arg: Expression) -> Expression:
+        return EqualsExpr(
+            arg,
+            Value(Decimal("NaN")),
+            output_field=fields.BooleanField(),
+        )
+
+
+class BaserowWhenNan(TwoArgumentBaserowFunction):
+    type = "when_nan"
+    arg1_type = [BaserowFormulaNumberType]
+    arg2_type = [BaserowFormulaNumberType]
+
+    def type_function(
+        self,
+        func_call: BaserowFunctionCall[UnTyped],
+        arg1: Union[BaserowExpression[BaserowFormulaNumberType]],
+        arg2: Union[BaserowExpression[BaserowFormulaNumberType]],
+    ) -> BaserowExpression[BaserowFormulaType]:
+        return func_call.with_valid_type(
+            calculate_number_type([arg1.expression_type, arg2.expression_type])
+        )
+
+    def to_django_expression(self, arg1: Expression, arg2: Expression) -> Expression:
+        return handle_arg_being_nan(arg1, arg2, arg1)
+
+
 class BaserowInt(BaserowTrunc):
     """
     Kept for backwards compatability as was introduced in v3 of formula language but

backend/tests/baserow/contrib/database/formula/test_baserow_formula_results.py

@@ -263,6 +263,12 @@ VALID_FORMULA_TESTS = [
     ("exp(-1.00)", "0.37"),
     ("exp(1/0)", "NaN"),
     ("exp(tonumber('invalid'))", "NaN"),
+    ("is_nan(1/0)", True),
+    ("is_nan(1)", False),
+    ("when_nan(1/0, 4)", "4.0000000000"),
+    ("when_nan(1.0, 4)", "1.0"),
+    ("when_nan(1, 4.0)", "1.0"),
+    ("when_nan(1/0, 1/0)", "NaN"),
     ("int(1.1234)", "1"),
     ("int(1.56)", "1"),
     ("int(-1.56)", "-1"),

changelog.md

@@ -16,6 +16,7 @@ For example:
 * Can add a row with textual values for single select, multiple select and link row field. [#1312](https://gitlab.com/bramw/baserow/-/issues/1312)
 * Add e2e tests. [#820](https://gitlab.com/bramw/baserow/-/issues/820)
 * Added missing actions for audit log. [#1500](https://gitlab.com/bramw/baserow/-/issues/1500)
+* Add `is_nan` and `when_nan` formula functions [#1527](https://gitlab.com/bramw/baserow/-/issues/1527)
 
 ### Bug Fixes
 * Add missing `procps` system package to all-in-one docker image fixing `/baserow/supervisor/docker-postgres-setup.sh run` (#1512)[https://gitlab.com/bramw/baserow/-/issues/1512]

web-frontend/locales/en.json

@@ -381,6 +381,8 @@
         "sqrtDescription": "Returns the square root of the argument provided.",
         "roundDescription": "Returns first argument rounded to the number of digits specified by the second argument.",
         "truncDescription": "Returns only the first argument converted into an integer by truncating any decimal places.",
+        "isNanDescription": "Returns true if the argument is 'NaN', returns false otherwise.",
+        "wheNanDescription": "Returns the first argument if it's not 'NaN'. Returns the second argument if the first argument is 'NaN'",
         "absDescription": "Returns the absolute value for the argument number provided.",
         "ceilDescription": "Returns the smallest integer that is greater than or equal the argument number provided.",
         "floorDescription": "Returns the largest integer that is less than or equal the argument number provided."

web-frontend/modules/database/formula/functions.js

@@ -1594,6 +1594,52 @@ export class BaserowTrunc extends BaserowFunctionDefinition {
   }
 }
 
+export class BaserowIsNaN extends BaserowFunctionDefinition {
+  static getType() {
+    return 'is_nan'
+  }
+
+  getDescription() {
+    const { i18n } = this.app
+    return i18n.t('formulaFunctions.isNanDescription')
+  }
+
+  getSyntaxUsage() {
+    return ['is_nan(number)']
+  }
+
+  getExamples() {
+    return ['is_nan(1 / 0) = true', 'is_nan(1) = false']
+  }
+
+  getFormulaType() {
+    return 'number'
+  }
+}
+
+export class BaserowWhenNaN extends BaserowFunctionDefinition {
+  static getType() {
+    return 'when_nan'
+  }
+
+  getDescription() {
+    const { i18n } = this.app
+    return i18n.t('formulaFunctions.whenNanDescription')
+  }
+
+  getSyntaxUsage() {
+    return ['when_nan(number, fallback)']
+  }
+
+  getExamples() {
+    return ['when_nan(1 / 0, 4) = 4', 'when_nan(1, 4) = 1']
+  }
+
+  getFormulaType() {
+    return 'number'
+  }
+}
+
 export class BaserowLeast extends BaserowFunctionDefinition {
   static getType() {
     return 'least'

web-frontend/modules/database/plugin.js

@@ -155,6 +155,8 @@ import {
   BaserowContains,
   BaserowFilter,
   BaserowTrunc,
+  BaserowIsNaN,
+  BaserowWhenNaN,
   BaserowEven,
   BaserowOdd,
   BaserowCeil,
@@ -458,6 +460,8 @@ export default (context) => {
   app.$registry.register('formula_function', new BaserowSum(context))
   app.$registry.register('formula_function', new BaserowFilter(context))
   app.$registry.register('formula_function', new BaserowTrunc(context))
+  app.$registry.register('formula_function', new BaserowIsNaN(context))
+  app.$registry.register('formula_function', new BaserowWhenNaN(context))
   app.$registry.register('formula_function', new BaserowEven(context))
   app.$registry.register('formula_function', new BaserowOdd(context))
   app.$registry.register('formula_function', new BaserowAbs(context))

web-frontend/test/unit/database/formula/formulaFunctions.spec.js

@@ -47,6 +47,7 @@ describe('Formula Functions Test', () => {
       'if',
       'equal',
       'isblank',
+      'is_nan',
       'not',
       'not_equal',
       'greater_than',
@@ -67,6 +68,7 @@ describe('Formula Functions Test', () => {
       'minus',
       'row_id',
       'when_empty',
+      'when_nan',
       'any',
       'every',
       'max',