Tip: Testing the templates on the fly

Testing the templates on the fly

echo 'Name: some-init-method' > /tmp/var.yaml

$ EASYGEN_TS='{{.Name}}' easygen /tmp/var
some-init-method

I.e., with the environment variable EASYGEN_TS, the .tmpl template file is not used.

Here are more examples:

$ EASYGEN_TS='{{.Name}}' easygen -ts '{{clk2uc .Name}}' /tmp/var
SomeInitMethod
# when both `EASYGEN_TS` environment variable and `-ts` option are provided, the latter takes precedence

$ easygen -ts '{{$n := sprintf .Name}} {{$n}}' /tmp/var.yaml
 some-init-method

$ easygen -ts '{{$n := sprintf "%s, %.2f" (clk2uc .Name) 12.3456}} {{$n}}' /tmp/var.yaml
 SomeInitMethod, 12.35

$ easygen -ts '{{substr (clk2uc .Name) 4}}' /tmp/var
InitMethod

$ easygen -ts '{{substr (clk2uc .Name) 8 3}}' /tmp/var
Met

$ easygen -ts '{{substr (clk2uc .Name) 4 -2}}' /tmp/var
InitMeth

$ easygen -ts '{{substr (clk2uc .Name) -6}}' /tmp/var
Method

$ easygen -ts '{{substr "abcde" -3}}' /tmp/var
cde

I.e., command line value takes the highest priority, even overriding the environment variable EASYGEN_TS's value.

As such, if you have a different naming convention than using .tmpl for template file and .yaml for data file, you can override them in environment variables, EASYGEN_ET and EASYGEN_EY, so that you don't need to use -et and/or -ey to override them from command line each time.

echo 'Name: myConstantVariable' > /tmp/var.yml

$ EASYGEN_EY=.yml easygen -ts '{{clc2ss .Name}}' /tmp/var
MY_CONSTANT_VARIABLE

Tips

You can use easygen as an generic Go template testing tool with the -ts commandline option. For example,

echo "Age: 16" > /tmp/age.yaml

$ easygen -ts "{{.Age}}" /tmp/age
16

$ easygen -ts '{{.Age}} {{ENV "SHELL"}}{{ENV "DISPLAY"}} ({{ENV "NONONO"}})' /tmp/age
16 /bin/bash:0 ()

$ easygen -ts '{{printf "%x" .Age}}' /tmp/age
10

$ easygen -ts '{{date "Y4"}}' /tmp/age
2017
$ 

$ easygen -ts '{{date "I"}}' /tmp/age
2017-07-10

$ easygen -ts '{{date "."}}' /tmp/age
2017.07.10

$ easygen -ts '{{date ""}}' /tmp/age
20170710

$ easygen -ts '{{timestamp}}' /tmp/age
2017-07-10T08:53:25-04:00

$ easygen -ts '{{timestamp "unix"}}' /tmp/age
1499691221

echo '{FirstName: John, LastName: Doe}' > /tmp/name.yaml

$ easygen -ts '{{.FirstName}}'\''s full name is {{printf "%s%s" .FirstName .LastName | len}} letters long.' /tmp/name
John's full name is 7 letters long.

$ easygen -ts "{{.FirstName}} {{clk2ss .LastName}}'s full name is "'{{len (printf "%s%s" .FirstName .LastName)}} letters long.' /tmp/name
John DOE's full name is 7 letters long.

echo 'Name: some-init-method' > /tmp/var.yaml

$ easygen -ts '{{.Name}} {{6 | minus1}} {{minus1 6}} {{clk2lc .Name}} {{clk2uc .Name}}' /tmp/var
some-init-method 5 5 someInitMethod SomeInitMethod

# More built-in function examples. See https://github.com/go-easygen/easygen/issues/25
$ easygen -ts '{{stringsContains .Name "init"}}' /tmp/var
true

$ easygen -ts '{{stringsContains .Name "foobar"}}' /tmp/var
false

$ easygen -ts '{{if (stringsContains .Name "init")}}"{{.Name}}" contains "init"{{else}} there {{end}}!' /tmp/var
"some-init-method" contains "init"!

$ easygen -ts '{{if (stringsContains .Name "init")}}"{{.Name}}" splits into: {{range (stringsSplit .Name "-")}}{{.}} {{end}}{{else}} there {{end}}!' /tmp/var
"some-init-method" splits into: some init method !

$ echo 'Name: "%bob'"'"'s file"' | tee /tmp/var.yaml
Name: "%bob's file"

$ easygen -ts '{{quote4shell .Name}}' /tmp/var
'%bob'\''s file'