How can I ignore a "$" in a DocumentContent to save in MongoDB? - mongodb

Question

My Problem is, that if I save a Document with a $ inside the content, Mongodb gives me an exception:
java.lang.IllegalArgumentException: Invalid BSON field name $ xxx
I would like that mongodb ignores the $ character in the content.
My Application is written in java. I read the content of the File and put it as a string into an object. After that the object will be saved with a MongoRepository class.
Someone has any ideas??
Example content
Edit: I heard mongodb has the same problem wit dot. Our Springboot found i workaround with dot, but not for dollar.
How to configure mongo converter in spring to encode all dots in the keys of map being saved in mongo db

Answer 1

If you are using Spring Boot you can extend MappingMongoConverter class and add override methods that do the escaping/unescaping.
#Component
public class MappingMongoConverterCustom extends MappingMongoConverter {
protected #Nullable
String mapKeyDollarReplacemant = "characters_to_replace_dollar";
protected #Nullable
String mapKeyDotReplacement = "characters_to_replace_dot";
public MappingMongoConverterCustom(DbRefResolver dbRefResolver, MappingContext<? extends MongoPersistentEntity<?>, MongoPersistentProperty> mappingContext) {
super(dbRefResolver, mappingContext);
}
#Override
protected String potentiallyEscapeMapKey(String source) {
if (!source.contains(".") && !source.contains("$")) {
return source;
}
if (mapKeyDotReplacement == null && mapKeyDollarReplacemant == null) {
throw new MappingException(String.format(
"Map key %s contains dots or dollars but no replacement was configured! Make "
+ "sure map keys don't contain dots or dollars in the first place or configure an appropriate replacement!",
source));
}
String result = source;
if(result.contains(".")) {
result = result.replaceAll("\\.", mapKeyDotReplacement);
}
if(result.contains("$")) {
result = result.replaceAll("\\$", mapKeyDollarReplacemant);
}
//add any other replacements you need
return result;
}
#Override
protected String potentiallyUnescapeMapKey(String source) {
String result = source;
if(mapKeyDotReplacement != null) {
result = result.replaceAll(mapKeyDotReplacement, "\\.");
}
if(mapKeyDollarReplacemant != null) {
result = result.replaceAll(mapKeyDollarReplacemant, "\\$");
}
//add any other replacements you need
return result;
}
}
If you go with this approach make sure you override the default converter from AbstractMongoConfiguration like below:
#Configuration
public class MongoConfig extends AbstractMongoConfiguration{
#Bean
public DbRefResolver getDbRefResolver() {
return new DefaultDbRefResolver(mongoDbFactory());
}
#Bean
#Override
public MappingMongoConverter mappingMongoConverter() throws Exception {
MappingMongoConverterCustom converter = new MappingMongoConverterCustom(getDbRefResolver(), mongoMappingContext());
converter.setCustomConversions(customConversions());
return converter;
}
.... whatever you might need extra ...
}