Type Coercion Methods
Last updated: 3 minutes read.
Bloblang provides a robust set of type coercion methods designed to facilitate seamless transformation and manipulation of data across various types. This includes converting values into booleans, numbers, strings or byte arrays.
bool
Attempt to parse a value into a boolean. An optional argument can be provided, in which case if the value cannot be parsed the argument will be returned instead. If the value is a number then any non-zero value will resolve to true, if the value is a string then any of the following values are considered valid: 1, t, T, TRUE, true, True, 0, f, F, FALSE.
Parameters
default <(optional) bool> An optional value to yield if the target cannot be parsed as a boolean.
Examples
root.foo = this.thing.bool()
root.bar = this.thing.bool(true)
bytes
Marshal a value into a byte array. If the value is already a byte array it is unchanged.
Examples
root.first_byte = this.name.bytes().index(0)
# In: {"name":"foobar bazson"}
# Out: {"first_byte":102}
not_empty
Ensures that the given string, array or object value is not empty, and if so returns it, otherwise an error is returned.
Examples
root.a = this.a.not_empty()
# In: {"a":"foo"}
# Out: {"a":"foo"}
# In: {"a":""}
# Out: Error("failed assignment (line 1): field `this.a`: string value is empty")
# In: {"a":["foo","bar"]}
# Out: {"a":["foo","bar"]}
# In: {"a":[]}
# Out: Error("failed assignment (line 1): field `this.a`: array value is empty")
# In: {"a":{"b":"foo","c":"bar"}}
# Out: {"a":{"b":"foo","c":"bar"}}
# In: {"a":{}}
# Out: Error("failed assignment (line 1): field `this.a`: object value is empty")
not_null
Ensures that the given value is not null, and if so returns it, otherwise an error is returned.
Examples
root.a = this.a.not_null()
# In: {"a":"foobar","b":"barbaz"}
# Out: {"a":"foobar"}
# In: {"b":"barbaz"}
# Out: Error("failed assignment (line 1): field `this.a`: value is null")
number
Attempt to parse a value into a number. An optional argument can be provided, in which case if the value cannot be parsed into a number the argument will be returned instead.
Parameters
default <(optional) float> An optional value to yield if the target cannot be parsed as a number.
Examples
root.foo = this.thing.number() + 10
root.bar = this.thing.number(5) * 10
string
Marshal a value into a string. If the value is already a string it is unchanged.
Examples
root.nested_json = this.string()
# In: {"foo":"bar"}
# Out: {"nested_json":"{\"foo\":\"bar\"}"}
root.id = this.id.string()
# In: {"id":228930314431312345}
# Out: {"id":"228930314431312345"}
type
Returns the type of a value as a string, providing one of the following values: string, bytes, number, bool, timestamp, array, object or null.
Examples
root.bar_type = this.bar.type()
root.foo_type = this.foo.type()
# In: {"bar":10,"foo":"is a string"}
# Out: {"bar_type":"number","foo_type":"string"}
root.type = this.type()
# In: "foobar"
# Out: {"type":"string"}
# In: 666
# Out: {"type":"number"}
# In: false
# Out: {"type":"bool"}
# In: ["foo", "bar"]
# Out: {"type":"array"}
# In: {"foo": "bar"}
# Out: {"type":"object"}
# In: null
# Out: {"type":"null"}
root.type = content().type()
# In: foobar
# Out: {"type":"bytes"}
root.type = this.ts_parse("2006-01-02").type()
# In: "2022-06-06"
# Out: {"type":"timestamp"}