Add ifError overloads for BooleanExpression

Author: MarkDuckworth

packages/firestore/src/lite-api/expressions.ts

@@ -2656,6 +2656,30 @@ export class BooleanExpression extends FunctionExpression {
       'conditional'
     );
   }
+
+  /**
+   * @beta
+   *
+   * Creates an expression that returns the `catch` argument if there is an
+   * error, else return the result of this expression.
+   *
+   * ```typescript
+   * // Create an expression that protects against a divide by zero error
+   * // but always returns a boolean expression.
+   * constant(50).divide('length').gt(1).ifError(constant(false));
+   * ```
+   *
+   * @param catchValue The value that will be returned if this expression
+   * produces an error.
+   * @return A new {@code Expr} representing the 'ifError' operation.
+   */
+  ifError(catchValue: BooleanExpression): BooleanExpression {
+    return new BooleanExpression(
+      'if_error',
+      [this, catchValue],
+      'ifError'
+    );
+  }
 }
 
 /**
@@ -2814,6 +2838,30 @@ export function isError(value: Expression): BooleanExpression {
   return value.isError();
 }
 
+/**
+ * @beta
+ *
+ * Creates an expression that returns the `catch` argument if there is an
+ * error, else return the result of the `try` argument evaluation.
+ *
+ * This overload is useful when a BooleanExpression is required.
+ *
+ * ```typescript
+ * // Create an expression that protects against a divide by zero error
+ * // but always returns a boolean expression.
+ * ifError(constant(50).divide('length').gt(1), constant(false));
+ * ```
+ *
+ * @param tryExpr The try expression.
+ * @param catchExpr The catch expression that will be evaluated and
+ * returned if the tryExpr produces an error.
+ * @return A new {@code Expr} representing the 'ifError' operation.
+ */
+export function ifError(
+  tryExpr: BooleanExpression,
+  catchExpr: BooleanExpression
+): BooleanExpression;
+
 /**
  * @beta
  *
@@ -2861,7 +2909,11 @@ export function ifError(
   tryExpr: Expression,
   catchValue: unknown
 ): FunctionExpression {
-  return tryExpr.ifError(valueToDefaultExpr(catchValue));
+  if (tryExpr instanceof BooleanExpression && catchValue instanceof BooleanExpression) {
+    return tryExpr.ifError(catchValue);
+  } else {
+    return tryExpr.ifError(valueToDefaultExpr(catchValue));
+  }
 }
 
 /**

packages/firestore/test/integration/api/pipeline.test.ts

@@ -2583,6 +2583,9 @@ apiDescribe.only('Pipelines', persistence => {
             ifError(divide(constant(1), constant(0)), constant('was error')).as(
               'ifError'
             ),
+            ifError(divide(constant(1), constant(0)).greaterThan(1), constant(true)).not().as(
+              'ifErrorBooleanExpression'
+            ),
             isAbsent('foo').as('isAbsent'),
             isNotNull('title').as('titleIsNotNull'),
             isNotNan('cost').as('costIsNotNan'),
@@ -2595,6 +2598,7 @@ apiDescribe.only('Pipelines', persistence => {
         ratingIsNaN: false,
         isError: true,
         ifError: 'was error',
+        ifErrorBooleanExpression: false,
         isAbsent: true,
         titleIsNotNull: true,
         costIsNotNan: false,
@@ -2615,6 +2619,9 @@ apiDescribe.only('Pipelines', persistence => {
             divide(constant(1), constant(0))
               .ifError(constant('was error'))
               .as('ifError'),
+            divide(constant(1), constant(0)).greaterThan(1).ifError(constant(true)).not().as(
+              'ifErrorBooleanExpression'
+            ),
             field('foo').isAbsent().as('isAbsent'),
             field('title').isNotNull().as('titleIsNotNull'),
             field('cost').isNotNan().as('costIsNotNan')
@@ -2625,6 +2632,7 @@ apiDescribe.only('Pipelines', persistence => {
         ratingIsNaN: false,
         isError: true,
         ifError: 'was error',
+        ifErrorBooleanExpression: false,
         isAbsent: true,
         titleIsNotNull: true,
         costIsNotNan: false