Golang return empty array instead of null. Should maps and slices be returned as a simpl...

Golang return empty array instead of null. Should maps and slices be returned as a simple nil value, or should an empty but instantiated value be returned? Sep 3, 2020 · In Go, we often need to return zero values. Marshal () as empty array [] instead of null. It seems to me @pjebs is trying to solve a different problem with the struct tag solution, and I'm curious what that is. Idiomatic Go encourages the use of guard clauses, and guard clauses necessitate the need to return early. range loop return the same results. Practically, many JSON parsers reject raw arrays that ar 258K subscribers in the golang community. When I initialize the f1 as var f1 []string, it is a nil pointer and when marshalled, it gives you null instead of []. If an empty string is returned, then the driver type name is not supported. May 18, 2019 · You are using struct for response instead of array of struct so current output is accurate one. Rather than returning what is traditionally expected, an empty array, it instead returns null. Consult your driver documentation for a list of driver data types. It renders a null value in JSON instead of an empty array []. To tell if a slice is empty, simply compare its length to 0: len(s) == 0. Jan 5, 2026 · In this blog, we’ll explore why null arrays cause issues, common scenarios where they appear in Gin, and step-by-step solutions to ensure your API always returns empty arrays [] instead of null. Converting a non- nil slice to an array pointer will result in a non- nil pointer, converting a nil slice to an array pointer will result in a nil pointer. 17). In Golang, an empty array can be declared in the following two ways. Should maps and slices be returned as a simple nil value, or should an empty but Jul 10, 2020 · One of the most frustrating things with Go is how it handles empty arrays when encoding JSON. When returning early with an error, by convention all other return values should be zero values. For About Golang: Recursively initialize all nil slices in a given object, so they json. Jun 30, 2022 · It is necessary to clarify the initialization method of arrays. Length specifiers are not included. Sep 3, 2020 · When returning early with an error, by convention all other return values should be zero values. The technical difference between them is that the nil slice has no backing array while the slice with no elements has a backing array but no items are stored in it (length of 0). Sep 2, 2021 · Empty and nil slices behave in the same way that is the built-in functions like len(), cap(), append(), and for . Marshal(). . Marshal'd), the second one is a slice with no items. Sep 9, 2018 · The problem I'm trying to solve is interoperability with Javascript. This is because otherwise you’re paying the cost of copying the struct. The first one is what you did initially which is a bill slice (null when json. This issue has a couple of open issues (ie. We would like to show you a description here but the site won’t allow us. So, since the nil slice declaration is simpler, you should prefer it to creating an empty slice. ColumnType. Jan 19, 2017 · Recently I came across this gotcha in Golang while I was writing a plugin for Gauge that generates JSON report. golang/go#27589) but none of the proposed solutions were accepted into the standard library as of Aug 2023. Feb 10, 2026 · DatabaseTypeName returns the database system name of the column type. Passing null means my browser-side code needs to handle an empty array in a non-idiomatic way, leading to more fragile code. Jan 19, 2017 · The reason for this was the way I had initialized the slice. Jun 1, 2017 · The only difference is by converting the slice to an array pointer (which was added to the language in Go 1. It seems from your code that you want to return only one struct at a time. var x interface{} x = 10 To fix this, I had to initialize the variable as f2 := make([]string, 0) and this gives you output as empty slice instead of null. Also, when not returning a simple type you should almost always return a pointer to a struct or an interface and these can be nil. May 2, 2019 · golang's stdlib encoding/json library currently marshals empty arrays as null rather than [], causing downstream JSON parsing to often fail. So instead of handling it via empty array, handle it on null. Has an empty object been retrieved or created and stored, or is it just a convenience for filling in the details. According to the Go json docs: So, if we implement the Marshalerinterface: Our MarshalJSON() will be called when encoding the data. Ask questions and post articles about the Go programming language and related tools, events etc. See the additional MarshalJSON()at line 14: This would then output: The Alias on line 15 is required to prevent an infinite loop when calling json. The confusion arises with data types like maps and slices. wnk yry xms ujc vru pfn wld cjy lga kvv hss chy qtm bwz iyf