Injection of null or an empty string as the default value of a property

Question

Is it possible to inject a null or blank string as the default value that will be used in a spring file if the property is not specified? Currently the best I have is

<constructor-arg index="1" value="@{data.url:&quot;&quot;}"/>

which resolves to "" in code

I think just `` should work. In case you need the index you may add it. Maybe I am not getting your question right? — Ivaylo Strandjev, Dec 11 '12 at 09:35
will always send an empty string. I'm interested in an empty string only if one is not specified in the associated properties file. Please see http://stackoverflow.com/a/2534949/222867 — qwerty, Dec 11 '12 at 09:44

score 15 · Answer 1 · answered Sep 16 '16 at 18:38

15

Empty-Elvis works for me...

@Value("${http.proxyHost?:}")
public String proxyHost = null;

answered Sep 16 '16 at 18:38

RMHarris157

269
2
9

Eclipse Oxygen generates an expression expected warning when I do this. It does work, though. I'm guessing this is an Eclipse issue. – David Bradley Jul 25 '18 at 17:13

Marcel Stör · Answer 2 · 2012-12-12T07:16:11.377

13

Have you tried using SpEL? Something like this maybe:

<constructor-arg index="1" value="#{'${data.url}'==null?'':'${data.url}'}"/>

Update

I just remembered that there's an easier way (as nicely described here). Try:

<constructor-arg index="1" value="${data.url:''}"/>

edited Dec 12 '12 at 07:16

answered Dec 12 '12 at 07:06

Marcel Stör

22,695
19
92
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In Spring 3.0.7 I made "#{ '${data.url}' != 'null' ? '${data.url}' : '' }" because just != null doesn't worked – Sergey Ponomarev May 02 '18 at 09:00

BrentR · Answer 3 · 2013-09-05T15:37:41.237

13

This will do the trick if you are using annotations in your source:

@Value("${data.url:#{null}}")
private String dataUrl;

edited Sep 05 '13 at 15:37

answered Sep 05 '13 at 15:31

BrentR

878
6
20

score 0 · Answer 4 · answered Jun 02 '23 at 10:31

0

If you want to set value as null:

@Value("${data.url:#{null}}")
private String dataUrl;

If you want to set value as empty string:

@Value("${data.url:}")
private String dataUrl;

answered Jun 02 '23 at 10:31

Rohan Deshmukh

1
1

score 0 · Answer 5 · answered Jun 02 '23 at 10:40

To inject an empty string as the default value, you can use the @Value annotation with the defaultValue attribute

@Value("${data.url:}")
private String dataUrl;

you can also define the property like:

@Value("${data.url:#{null}}")
private String dataUrl;

Injection of null or an empty string as the default value of a property

5 Answers5