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fix(mariadb): json gt/gte/lt/lte comparisons #315
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Weakky
commented
Aug 23, 2021
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| fn value_into_json(value: &Value) -> Option<serde_json::Value> { | ||
| match value.clone() { | ||
| // MariaDB returns JSON as text | ||
| Value::Text(Some(text)) => { | ||
| let json: serde_json::Value = | ||
| serde_json::from_str(&text).expect(format!("expected parsable text to json, found {}", text).as_str()); | ||
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| Some(json) | ||
| } | ||
| Value::Json(Some(json)) => Some(json), | ||
| _ => None, | ||
| } | ||
| } |
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I ended up using an external helper and not adding a match to Value::as_json() because it's a const method and serde_json::from_str is not const so it cannot work. And changing the const method to a normal method I believe is a breaking change that wasn't worth it.
Weakky
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Aug 23, 2021
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| fn json_to_quaint_value<'a>(json: serde_json::Value) -> crate::Result<Value<'a>> { | ||
| match json { | ||
| serde_json::Value::String(str) => Ok(Value::text(str)), | ||
| serde_json::Value::Number(number) => { | ||
| if let Some(int) = number.as_i64() { | ||
| Ok(Value::integer(int)) | ||
| } else if let Some(float) = number.as_f64() { | ||
| Ok(Value::double(float)) | ||
| } else { | ||
| unreachable!() | ||
| } | ||
| } | ||
| x => { | ||
| let msg = format!("Expected JSON string or number, found: {}", x); | ||
| let kind = ErrorKind::conversion(msg.clone()); | ||
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| let mut builder = Error::builder(kind); | ||
| builder.set_original_message(msg); | ||
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| Err(builder.build()) | ||
| } | ||
| } | ||
| } |
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This is the actual fix. We no longer use CAST (? AS JSON) but instead render the values deserialized, which works both on MySQL & MariaDB
Weakky
commented
Aug 23, 2021
| (left, right) if left.is_json_value() && right.is_json_extract_fun() => { | ||
| self.surround_with("CAST(", " AS JSON)", |s| s.visit_expression(left))?; | ||
| let quaint_value = json_to_quaint_value(left.into_json_value().unwrap())?; |
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Usage of the function above
8 tasks
This was referenced Aug 23, 2021
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Overview
Follow-up PR to #311
It turns out
CAST(? as JSON)is not supported by MariaDB. We work around this limitation by no longer rendering a JSON value compared toJSON_EXTRACT()as JSON, but as its parsed type.As a result though, it is no longer possible to perform numeric comparisons with
JSON_EXTRACT()as the left/right and a JSON value as the left/right member that's NOT a number or a string.Examples
Additional notes
Since we added MySQL8 and MariaDB to the list of tested databases, some failing tests have appeared. I created an issue to track this: #318