upgrade ints and floats in arrays with mixed sizes

Author: grische

json-to-go.js

@@ -111,6 +111,11 @@ function jsonToGo(json, typename, flatten = true, example = false, allOmitempty
 									continue
 								}
 
+								// if variable was first detected as int (7) and a second time as float64 (3.14)
+								// then we want to select float64, not int. Similar for int64 and float64.
+								if(areSameType(currentValue, 1))
+									allFields[keyname].value = findBestValueForNumberType(existingValue, currentValue);
+
 								if (areObjects(existingValue, currentValue)) {
 									const comparisonResult = compareObjectKeys(
 										Object.keys(currentValue),
@@ -389,6 +394,50 @@ function jsonToGo(json, typename, flatten = true, example = false, allOmitempty
 		}
 	}
 
+	// change the value to expand ints and floats to their larger equivalent
+	function findBestValueForNumberType(existingValue, newValue) {
+		if (!areSameType(newValue, 1)) {
+			console.error(`Error: currentValue ${newValue} is not a number`)
+			return null // falls back to goType "any"
+		}
+
+		const newGoType = goType(newValue)
+		const existingGoType = goType(existingValue)
+
+		if (newGoType === existingGoType)
+			return existingValue
+
+		// always upgrade float64
+		if (newGoType === "float64")
+			return newValue
+		if (existingGoType === "float64")
+			return existingValue
+
+		// it's too complex to distinguish int types and float32, so we force-upgrade to float64
+		// if anyone has a better suggestion, PRs are welcome!
+		if (newGoType.includes("float") && existingGoType.includes("int"))
+			return Number.MAX_VALUE
+		if (newGoType.includes("int") && existingGoType.includes("float"))
+			return Number.MAX_VALUE
+
+		if (newGoType.includes("int") && existingGoType.includes("int")) {
+			const existingValueAbs = Math.abs(existingValue);
+			const newValueAbs = Math.abs(newValue);
+
+			// if the sum is overflowing, it's safe to assume numbers are very large. So we force int64.
+			if (!isFinite(existingValueAbs + newValueAbs))
+				return Number.MAX_SAFE_INTEGER
+
+			// it's too complex to distinguish int8, int16, int32 and int64, so we just use the sum as best-guess
+			return existingValueAbs + newValueAbs;
+		}
+
+		// There should be other cases
+		console.error(`Error: something went wrong with findBestValueForNumberType() using the values: '${newValue}' and '${existingValue}'`)
+		console.error("       Please report the problem to https://github.com/mholt/json-to-go/issues")
+		return null // falls back to goType "any"
+	}
+
 	// Given two types, returns the more specific of the two
 	function mostSpecificPossibleGoType(typ1, typ2)
 	{

json-to-go.test.js

@@ -162,6 +162,7 @@ function testFiles() {
   const testCases = [
     "duplicate-top-level-structs",
     "double-nested-objects",
+    "array-with-mixed-float-int",
     "array-with-nonmatching-types",
   ];
 

tests/array-with-mixed-float-int.go

@@ -0,0 +1,13 @@
+type AutoGenerated struct {
+	AgeOfTheUniverse []AgeOfTheUniverse `json:"age of the universe"`
+	AgeOfTheEarth []AgeOfTheEarth `json:"age of the earth"`
+	Date string `json:"date"`
+}
+type AgeOfTheUniverse struct {
+	Name string `json:"name"`
+	Value float64 `json:"value"`
+}
+type AgeOfTheEarth struct {
+	Name string `json:"name"`
+	Value int64 `json:"value"`
+}

tests/array-with-mixed-float-int.json

@@ -0,0 +1,31 @@
+{
+    "age of the universe": [
+        {
+            "name": "in years",
+            "value": 1378700000
+        },
+        {
+            "name": "in seconds",
+            "value": 4.35075327952992e+17
+        },
+        {
+            "name": "in kapla",
+            "value": 0.31914351851
+        }
+    ],
+    "age of the earth": [
+        {
+            "name": "in eons (roughly)",
+            "value": 4
+        },
+        {
+            "name": "in years",
+            "value": 4.543e9
+        },
+        {
+            "name": "in seconds",
+            "value": 1.6592953e+12
+        }
+    ],
+    "date": "2024-07-25"
+}