86 lines
3.2 KiB
Markdown
86 lines
3.2 KiB
Markdown
node-red-node-mongodb
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=====================
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A <a href="http://nodered.org" target="_new">Node-RED</a> node to save data in a MongoDB database.
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**Note** : This is the same node as was in the core of Node-RED.
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As of v0.10.8 you will need to install it from here if still required.
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Pre-requisite
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-------------
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To run this you need a local MongoDB server running. For details see
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<a href="https://www.mongodb.org/" target="_new">the MongoDB site</a>.
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Install
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-------
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Run the following command in your Node-RED user directory - typically `~/.node-red`
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npm install node-red-node-mongodb
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Usage
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-----
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Nodes to save and retrieve data in a local MongoDB instance.
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### Input
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Calls a MongoDB collection method based on the selected operator.
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*Find* queries a collection using the `msg.payload` as the query statement as
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per the *.find()* function.
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Optionally, you may also (via a function) set
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- a `msg.projection` object to constrain the returned fields,
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- a `msg.sort` object,
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- a `msg.limit` number,
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- a `msg.skip` number.
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*Count* returns a count of the number of documents in a collection or matching a
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query using the `msg.payload` as the query statement.
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*Aggregate* provides access to the aggregation pipeline using the `msg.payload` as the pipeline array.
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You can either set the collection method in the node config or on `msg.collection`.
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Setting it in the node will override `msg.collection`.
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See the <a href="http://docs.mongodb.org/manual/reference/method/db.collection.find/" target="new">*MongoDB collection methods docs*</a> for examples.
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The result is returned in `msg.payload`.
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### Output
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A simple MongoDB output node. Can save, insert, update and remove objects from a chosen collection.
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MongoDB only accepts objects.
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Save and insert can either store `msg` or `msg.payload`. If msg.payload is
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selected it should contain an object. If not it will be wrapped in an object with a name of payload.
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*Save* will update an existing object or insert a new object if one does not already exist.
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*Insert* will insert a new object.
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*Update* will modify an existing object or objects. The query to select objects
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to update uses `msg.query` and the update to the element uses `msg.payload`.
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Update can add an object if it does not exist or update multiple objects.
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*Remove* will remove objects that match the query passed in on `msg.payload`.
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A blank query will delete *all of the objects* in the collection.
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You can either set the collection method in the node config or on `msg.collection`.
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Setting it in the node will override `msg.collection`.
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By default MongoDB creates an `msg._id` property as the primary key - so
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repeated injections of the same `msg` will result in many database entries.
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If this is NOT the desired behaviour - ie. you want repeated entries to overwrite,
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then you must set the `msg._id` property to be a constant by the use of a previous function node.
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This must be done at the correct level. If only writing msg.payload then payload must contain the \_id property.
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If writing the whole msg object then it must contain an \_id property.
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This could be a unique constant or you could create one based on some other msg property.
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Currently we do not limit or cap the collection size at all...
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