127 lines
4.2 KiB
JavaScript
127 lines
4.2 KiB
JavaScript
/* Copyright 2016 Mozilla
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use
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* this file except in compliance with the License. You may obtain a copy of the
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* License at http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software distributed
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* under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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* CONDITIONS OF ANY KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations under the License.
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*/
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var datomish = require("../../target/release-node/datomish.js");
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var schema = {
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"name": "pages",
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"attributes": [
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{"name": "page/url",
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"type": "string",
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"cardinality": "one",
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"unique": "identity",
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"doc": "A page's URL."},
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{"name": "page/title",
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"type": "string",
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"cardinality": "one",
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"doc": "A page's title."}
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]
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};
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async function testOpen() {
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// Open a database.
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let path = "/tmp/testing" + Date.now() + ".db";
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console.log("Opening " + path);
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let db = await datomish.open(path);
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// Make sure we have our current schema.
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await db.ensureSchema(schema);
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// Add some data. Note that we use a temporary ID (the real ID
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// will be assigned by Datomish).
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let txResult = await db.transact([
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{"db/id": datomish.tempid(),
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"page/url": "https://mozilla.org/",
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"page/title": "Mozilla"}
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]);
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console.log("Transaction returned " + JSON.stringify(txResult));
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console.log("Transaction instant: " + txResult.txInstant);
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// A simple query.
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let results = await db.q("[:find [?url ...] :in $ :where [?e :page/url ?url]]");
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console.log("Known URLs: " + JSON.stringify(results));
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// Let's extend our schema. In the real world this would typically happen
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// across releases.
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schema.attributes.push({"name": "page/visitedAt",
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"type": "instant",
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"cardinality": "many",
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"doc": "A visit to the page."});
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await db.ensureSchema(schema);
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// Now we can make assertions with the new vocabulary about existing
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// entities.
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// Note that we simply let Datomish find which page we're talking about by
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// URL -- the URL is a unique property -- so we just use a tempid again.
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await db.transact([
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{"db/id": datomish.tempid(),
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"page/url": "https://mozilla.org/",
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"page/visitedAt": new Date()}
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]);
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// When did we most recently visit this page?
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let date = (await db.q(
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`[:find (max ?date) .
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:in $ ?url
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:where
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[?page :page/url ?url]
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[?page :page/visitedAt ?date]]`,
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{"inputs": {"url": "https://mozilla.org/"}}));
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console.log("Most recent visit: " + date);
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// Add some more data about a couple of pages.
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let start = Date.now();
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let lr = datomish.tempid();
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let reddit = datomish.tempid();
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let res = await db.transact([
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{"db/id": reddit,
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"page/url": "http://reddit.com/",
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"page/title": "Reddit",
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"page/visitedAt": new Date(start)},
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{"db/id": lr,
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"page/url": "https://longreads.com/",
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"page/title": "Longreads: The best longform stories on the web",
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"page/visitedAt": (new Date(start + 100))},
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// Two visits each.
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{"db/id": lr,
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"page/visitedAt": (new Date(start + 200))},
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{"db/id": reddit,
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"page/visitedAt": (new Date(start + 300))}
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]);
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// These are our new persistent IDs. We can use these directly in later
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// queries or transactions
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lr = res.tempid(lr);
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reddit = res.tempid(reddit);
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console.log("Persistent IDs are " + lr + ", " + reddit + ".");
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// A query with a limit and order-by. Because we limit to 2, and order
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// by most recent visit date first, we won't get mozilla.org in our results.
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let recent = await db.q(
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`[:find ?url (max ?date)
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:in $
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:where
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[?page :page/url ?url]
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[?page :page/visitedAt ?date]]`,
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{"limit": 2, "order-by": [["_max_date", "desc"]]});
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console.log("Recently visited: " + JSON.stringify(recent));
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// Close: we're done!
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await db.close();
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}
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testOpen()
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.then((r) => console.log("Done."))
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.catch((e) => console.log("Failure: " + e.stack));
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