use serde_json;
use params::{Map, Value};
pub fn validate_json(values: &Map, field: &[&str]) -> Result<Option<Value>, String> {
match values.find(field) {
Some(&Value::String(ref value)) => {
if value.is_empty() {
return Ok(None);
}
if serde_json::from_str::<serde_json::Value>(value).is_ok() {
return Ok(None);
}
Err(format!("The {} field must contain a valid JSON string.",
field.last()
.unwrap()
.to_lowercase()
.replace("_", " ")))
}
None => {
Ok(None)
}
_ => {
Err(format!("The {} field must contain a valid JSON string.",
field.last()
.unwrap()
.to_lowercase()
.replace("_", " ")))
}
}
}