前言

MongoDB是面向集合存儲(chǔ)的文檔型數(shù)據(jù)庫(kù)，其涉及到的基本概念與關(guān)系型數(shù)據(jù)庫(kù)比有所不同。本文主要介紹關(guān)于mongo數(shù)據(jù)集合屬性存在點(diǎn)號(hào)(.)的相關(guān)內(nèi)容，下面話不多說(shuō)了，來(lái)一起看看詳細(xì)的介紹吧

基本知識(shí)點(diǎn)：

1.似乎mongo3.6之前不允許插入帶點(diǎn)（.）或美元符號(hào)（$）的鍵，但是當(dāng)我使用mongoimport工具導(dǎo)入包含點(diǎn)的JSON文件時(shí)，它工作正常。

2.在使用spring-data-mongodb處理mongodb的增刪改查時(shí)會(huì)通過(guò)一個(gè)MappingMongoConverter(Document和Modle轉(zhuǎn)換類(lèi))轉(zhuǎn)換數(shù)據(jù)

3.具體對(duì)點(diǎn)號(hào)的轉(zhuǎn)換在DBObjectAccessor(spring-data-mongodb-1.10.13)或者DocumentAccessor(spring-data-mongodb-2.0.9)，如下：

//插入時(shí)轉(zhuǎn)換
public void put(MongoPersistentProperty prop, Object value) {
Assert.notNull(prop, “MongoPersistentProperty must not be null!”);
String fieldName = prop.getFieldName();
if (!fieldName.contains(“.”)) {
dbObject.put(fieldName, value);
return;
}
Iterator<String> parts = Arrays.asList(fieldName.split(“\.”)).iterator();
DBObject dbObject = this.dbObject;
while (parts.hasNext()) {
String part = parts.next();
if (parts.hasNext()) {
dbObject = getOrCreateNestedDbObject(part, dbObject);
} else {
dbObject.put(part, value);
}
}
}

//查詢時(shí)轉(zhuǎn)換
public Object get(MongoPersistentProperty property) {
String fieldName = property.getFieldName();
if (!fieldName.contains(“.”)) {
return this.dbObject.get(fieldName);
}
Iterator<String> parts = Arrays.asList(fieldName.split(“\.”)).iterator();
Map<String, Object> source = this.dbObject;
Object result = null;
while (source != null && parts.hasNext()) {
result = source.get(parts.next());
if (parts.hasNext()) {
source = getAsMap(result);
}
}
return result;
}

//判斷值是否為空
public boolean hasValue(MongoPersistentProperty property) {
Assert.notNull(property, “Property must not be null!”);
String fieldName = property.getFieldName();
if (!fieldName.contains(“.”)) {
return this.dbObject.containsField(fieldName);
}
String[] parts = fieldName.split(“\.”);
Map<String, Object> source = this.dbObject;
Object result = null;
for (int i = 1; i < parts.length; i++) {
result = source.get(parts[i – 1]);
source = getAsMap(result);
if (source == null) {
return false;
}
}
return source.containsKey(parts[parts.length – 1]);
}