Collections

Convert a value that may arrive in several shapes (a native list or map, or the same as a JSON or YAML string) into a list, a map or a string, so the functions after it see one shape.

Read lists and maps without guarding every step: get an element by index or a value by key, test membership, take keys and values, or keep and drop keys. Out-of-range and missing keys give zero values, not errors.

Reference

Functions

asList

asList converts input to []interface{}. Accepts native slice, YAML list string, or JSON array string.

{{ asList "[\"us-east-1\",\"eu-west-1\"]" }}  → [us-east-1 eu-west-1]
{{ len (asList .spec.regions) }}  → 2

asMap

asMap converts input to map[string]interface{}. Accepts native map, YAML map string, or JSON object string.

{{ (asMap "{\"tier\":\"web\"}").tier }}  → "web"

asString

asString converts any value to a string. For maps and slices this produces a JSON encoding.

{{ asString 3 }}                   → "3"
{{ asString .deployment.spec.replicas }}  → "3"

listGet

listGet returns the element at a given index. Returns nil for out-of-range indices — no panic.

{{ listGet .spec.regions 0 }}  → "us-east-1"
{{ listGet .spec.regions 9 }}  → <no value>

listHas

listHas reports whether a list contains a value. Comparison is by ==.

{{ listHas .spec.regions "eu-west-1" }}  → true

listLen

listLen returns the number of elements in a list. Returns 0 for non-lists.

{{ listLen .spec.regions }}  → 2

mapGet

mapGet returns a map value by key. Returns nil when the map is absent or the key is missing.

{{ mapGet .deployment.metadata.labels "app" }}      → "web"
{{ mapGet .deployment.metadata.labels "missing" }}  → <no value>

mapKeys

mapKeys returns all keys of a map as sorted []string. Returns an empty slice for non-maps.

{{ mapKeys .spec.selector }}  → [app tier]

mapOmit

mapOmit returns a new map with the specified keys removed.

{{ mapOmit .metadata.labels "internal-key" "debug" }}

mapPick

mapPick returns a new map containing only the specified keys. Missing keys are silently omitted.

{{ mapPick .spec "image" "replicas" }}

mapValues

mapValues returns all values of a map as []interface{}. Returns an empty slice for non-maps.

{{ len (mapValues .spec.selector) }}  → 2