Simple Properties

A simple-to-use out of the box, properties loader

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How to use

What gets loaded

The default properties handler loads property values from files under the /resource project directory. These can be a mix of basic properties (.properties), yaml (.yaml) or JSON files (.json). Load order priority is .yaml least, .json middle to .properties highest.

File names

The first file(s) to check & load is bootstrap.<yaml/json/properties>. This cannot contain expressions for evaluation, i.e. properties are just key=value type. Any expression found will be a treated as a fatal error. This loading takes place when the Properties struct is created and a pointer is handed to the application. e.g.

properties := simpleProperties.DefaultProperties()

which is a shorthand way of saying

var properties *simpleProperties.Properties = simpleProperties.DefaultProperties()

The second stage of loading looks for files named application.<yaml/json/properties>. This is triggered by the following operation.

properties.Load()

If any property loaded has the key of profile, then any associated values are used to load further files. For example, if the following exists:

Note: The evaluation of property expression is carried out once the load operations have completed as part of the Load() call

profile=dev,xyzzy

then the following files are checked and loaded:

application_dev.<yaml/json/properties>
application_xyzzy.<yaml/json/properties>

In summary, loading file order is

boostrap.<yaml/json/properties>
application.<yaml/json/properties>
application_<profile_name>.<yaml/json/properties>

CLI Properties

Properties can also be added via the command line. For example, if the following where on the command line...

-p1=abc something -=pqr -ghi= -p2=plugh

then the three properties p1=abc, ghi= and p2=plugh would be loaded. Note that CLI properties are the highest priority and will override anything loaded from files.

Property Expressions and Default Values

Expressions can be used the RHS of property declarations. Each named value is delimited by ${}. A default value can also be specified by adding a colon after the property name and then stating the default. e.g. ${value:defaultValue}

If we had the following properties:

p1=Hello ${name}
name=Fred
p2=Hello ${another:World}

Then this would evaluate to:

p1=Hello Fred
name=Fred
p2=Hello World

Note: related properties do not need to be in one file. In the example above, each line could be in separate files and evaluation of expressions only occurs once all loading is completed (Including CLI properties)

Get the library

Add this:

go get -u github.com/codesqueak/simpleProperties/pkg/simpleProperties@vlatest

In Project Code to Import

Add this

import (
	"github.com/codesqueak/simpleProperties/pkg"
)

In project code to use

Add this

	properties := simpleProperties.DefaultProperties()
	properties.Load()
	var p1 = properties.GetProperty("p1")