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This article mainly introduces "mongodb import and export data methods". In daily operation, I believe many people have doubts about mongodb import and export data methods. Xiaobian consulted all kinds of materials and sorted out simple and easy operation methods. I hope to help you answer the doubts of "mongodb import and export data methods"! Next, please follow the small series to learn together!

MongoDB provides the mongoexport tool, which allows you to export a collection to a json or csv file. You can specify which data items to export, or you can export data based on given conditions. The tool help information is as follows:

[root@localhost bin]# ./ mongoexport --help options: --help produce help message -v [ --verbose ] be more verbose (include multiple times for more verbosity e.g. -vvvvv) -h [ --host ] arg mongo host to connect to ( /s1,s2 for sets) --port arg server port. Can also use --host hostname:port --ipv6 enable IPv6 support (disabled by default) -u [ --username ] arg username -p [ --password ] arg password --dbpath arg directly access mongod database files in the given path, instead of connecting to a mongod server - needs to lock the data directory, so cannot be used if a mongod is currently accessing the same path --directoryperdb if dbpath specified, each db is in a separate directory -d [ --db ] arg database to use -c [ --collection ] arg collection to use (some commands) -f [ --fields ] arg comma separated list of field names e.g. -f name,age --fieldFile arg file with fields names - 1 per line -q [ --query ] arg query filter, as a JSON string --csv export to csv instead of json -o [ --out ] arg output file; if not specified, stdout is used --jsonArray output to a json array rather than one object per line [root@localhost bin]#

Here is a practical example of how this tool can be used:

Export table t1 in foo library to json format:

[root@localhost bin]# ./ mongoexport -d foo -c t1 -o /data/t1.json connected to: 127.0.0.1 exported 1 records [root@localhost bin]#

After exporting successfully, let's take a look at the style of the/data/t1.json file and see if it is what we want:

root@localhost data]# more t1.json { "_id" : { "$oid" : "4f927e2385b7a6814a0540a0" }, "age" : 2 } [root@localhost data]#

The export is successful through the above instructions, but there is a problem, what if the migration of heterogeneous databases? For example, if we want to import MongoDB data into MySQL, what should we do? MongoDB provides a csv export format that can solve the problem of heterogeneous database migration. The age and name columns of t2 table of foo library are exported as follows:

[root@localhost bin]# ./ mongoexport -d foo -c t2 --csv -f age,name -o /data/t2.csv connected to: 127.0.0.1 exported 1 records [root@localhost bin]#

View export results for/data/t2.csv

[root@localhost data]# more t2.csv age,name 1,"wwl" [root@localhost data]#

mongoimport tool

MongoDB provides the mongoimport utility, which allows you to import the contents of a file in a particular format into a collection. The tool help information is as follows:

[root@localhost bin]# ./ mongoimport --help options: --help produce help message -v [ --verbose ] be more verbose (include multiple times for more verbosity e.g. -vvvvv) -h [ --host ] arg mongo host to connect to ( /s1,s2 for sets) --port arg server port. Can also use --host hostname:port --ipv6 enable IPv6 support (disabled by default) -u [ --username ] arg username -p [ --password ] arg password --dbpath arg directly access mongod database files in the given path, instead of connecting to a mongod server - needs to lock the data directory, so cannot be used if a mongod is currently accessing the same path --directoryperdb if dbpath specified, each db is in a separate directory -d [ --db ] arg database to use -c [ --collection ] arg collection to use (some commands) -f [ --fields ] arg comma separated list of field names e.g. -f name,age --fieldFile arg file with fields names - 1 per line --ignoreBlanks if given, empty fields in csv and tsv will be ignored --type arg type of file to import. default: json (json,csv,tsv) --file arg file to import from; if not specified stdin is used --drop drop collection first --headerline CSV,TSV only - use first line as headers --upsert insert or update objects that already exist --upsertFields arg comma-separated fields for the query part of the upsert. You should make sure this is indexed --stopOnError stop importing at first error rather than continuing --jsonArray load a json array, not one item per line. Currently limited to 4MB.

Here is a practical example of how to use this tool:

Let's look at the t1 table data in foo library:

> db.t1.find(); { "_id" : ObjectId("4f937a56450beadc560feaa9"), "age" : 5 } >

t1 There is a record with age=5, let's look at what the data in the json file looks like:

[root@localhost data]# more t1.json { "_id" : { "$oid" : "4f937a56450beadc560feaa7" }, "age" : 8 } [root@localhost data]#

You can see that there is an age=8 data in the t1.json file. Below we will import the records in the json file into the t1 table with the mongoimport tool:

[root@localhost bin]# ./ mongoimport -d foo -c t1 /data/t1.json connected to: 127.0.0.1 imported 1 objects

The tool returns information indicating that a record was inserted into the table. Let's go into the library and actually verify it:

[root@localhost bin]# ./ mongo MongoDB shell version: 1.8.1 connecting to: test > use foo switched to db foo > db.t1.find(); { "_id" : ObjectId("4f937a56450beadc560feaa9"), "age" : 5 } { "_id" : ObjectId("4f937a56450beadc560feaa7"), "age" : 8 } > At this point, the study of "mongodb import and export data methods" is over, hoping to solve everyone's doubts. Theory and practice can better match to help everyone learn, go and try it! If you want to continue learning more relevant knowledge, please continue to pay attention to the website, Xiaobian will continue to strive to bring more practical articles for everyone!

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