Converts a plain object to a DynamoDB expression with all variables and names
replaced with safe placeholders. It supports Condition, KeyCondition, Filter, Projection and Update expressions. The resulting expressions can then be used with AWS.DynamoDB.DocumentClient requests.
import dynoexpr from '@tuplo/dynoexpr';
const params = dynoexpr({
KeyCondition: { id: '567' },
Condition: { rating: '> 4.5' },
Filter: { color: 'blue' },
Projection: ['weight', 'size'],
});
/*
{
KeyConditionExpression: '(#nca40fdf5 = :v8dcca6b2)',
ExpressionAttributeValues: {
':v8dcca6b2': '567',
':vc95fafc8': 4.5,
':v792aabee': 'blue'
},
ConditionExpression: '(#n0f1c2905 > :vc95fafc8)',
FilterExpression: '(#n2d334799 = :v792aabee)',
ProjectionExpression: '#neb86488e,#n0367c420',
ExpressionAttributeNames: {
'#nca40fdf5': 'id',
'#n0f1c2905': 'rating',
'#n2d334799': 'color',
'#neb86488e': 'weight',
'#n0367c420': 'size'
}
}
*/$ npm install @tuplo/dynoexpr
# or with yarn
$ yarn add @tuplo/dynoexprconst docClient = new AWS.DynamoDB.DocumentClient();
const params = dynoexpr({
KeyCondition: {
HashKey: 'key',
RangeKey: 'between 2015 and 2019',
},
});
const results = await docClient
.query({ TableName: 'table', ...params })
.promise();You can use multiple expressions on the same field, by packing them into an array and assigning it to the key with the field's name.
const params = dynoexpr({
Condition: {
color: ['attribute_not_exists', 'yellow', 'blue'],
},
ConditionLogicalOperator: 'OR',
});
/*
{
ConditionExpression: '(attribute_not_exists(#n2d334799)) OR (#n2d334799 = :v0d81c8cd) OR (#n2d334799 = :v792aabee)',
ExpressionAttributeNames: {
'#n2d334799': 'color'
},
ExpressionAttributeValues: {
':v0d81c8cd': 'yellow',
':v792aabee': 'blue'
}
}
*/DynamoDB supports a number of functions to be evaluated when parsing expressions. You don't need to reference the path argument because that's identified by the object's key.
const params = dynoexpr({
Condition: {
docs: 'attribute_exists',
brand: 'attribute_not_exists',
extra: 'attribute_type(NULL)',
color: 'begins_with dark',
address: 'contains(Seattle)',
description: 'size < 20',
},
});
/*
{
ConditionExpression: '(attribute_exists(#nd0a55266)) AND (attribute_not_exists(#n4e5f8507)) AND (attribute_type(#n4a177797,:v64b0a475)) AND (begins_with(#n2d334799,:v1fdc3f67)) AND (contains(#n3af77f77,:v26425a2a)) AND (size(#nb6c8f268) < :vde9019e3)',
ExpressionAttributeNames: {
'#nd0a55266': 'docs',
'#n4e5f8507': 'brand',
'#n4a177797': 'extra',
'#n2d334799': 'color',
'#n3af77f77': 'address',
'#nb6c8f268': 'description'
},
ExpressionAttributeValues: {
':v64b0a475': 'NULL',
':v1fdc3f67': 'dark',
':v26425a2a': 'Seattle',
':vde9019e3': 20
}
}
*/const params = dynoexpr({
Update: { Sum: 'Sum + 20' },
Condition: { Sum: `< 100` },
});
/*
{
ConditionExpression: '(#n5af617ef < :va88c83b0)',
ExpressionAttributeNames: {
'#n5af617ef': 'Sum'
},
ExpressionAttributeValues: {
':va88c83b0': 100,
':vde9019e3': 20
},
UpdateExpression: 'SET #n5af617ef = #n5af617ef + :vde9019e3'
}
*/If a value is provided as a Set, it will be converted to DocumentClient.DynamoDbSet. But dynoexpr doesn't include DocumentClient so you need to provide it.
import { DocumentClient } from "aws-sdk/clients/dynamodb";
const params = dynoexpr({
DocumentClient,
Update: {
Color: new Set(['Orange', 'Purple'])
},
})
/*
{
UpdateExpression: 'SET #n8979552b = :v3add0a80',
ExpressionAttributeNames: {
'#n8979552b': 'Color'
},
ExpressionAttributeValues: {
':v3add0a80': Set { wrapperName: 'Set', values: [Array], type: 'String' }
}
}
*/import { DocumentClient } from "aws-sdk/clients/dynamodb";
const params = dynoexpr({
DocumentClient,
UpdateAdd: {
Color: ['Orange', 'Purple']
}
})
/*
{
UpdateExpression: 'ADD #ndc9f7295 :v3add0a80',
ExpressionAttributeNames: {
'#ndc9f7295': 'Color'
},
ExpressionAttributeValues: {
':v3add0a80': Set { wrapperName: 'Set', values: [Array], type: 'String' }
}
}
*/const params = dynoexpr({
Filter: { color: 'blue' },
ProjectionExpression: '#year',
ExpressionAttributeNames: {
'#year': 'year',
},
});
/*
{
ProjectionExpression: '#year',
ExpressionAttributeNames: {
'#year': 'year',
'#n2d334799': 'color'
},
FilterExpression: '(#n2d334799 = :v792aabee)',
ExpressionAttributeValues: {
':v792aabee': 'blue'
}
}
*/You can provide a path to an attribute on a deep object, each node will be escaped.
const params = dynoexpr({
Update: {
'foo.bar.baz': 'foo.bar.baz + 1'
}
});
/*
{
ExpressionAttributeNames: {
"#n22f4f0ae": "bar",
"#n5f0025bb": "foo",
"#n82504b33": "baz",
},
ExpressionAttributeValues: {
":vc823bd86": 1,
},
UpdateExpression:
"SET #n5f0025bb.#n22f4f0ae.#n82504b33 = #n5f0025bb.#n22f4f0ae.#n82504b33 + :vc823bd86",
}
*/If one of the nodes needs to escape some of its characters, use double quotes around it, like this:
const params = dynoexpr({
Update: {
'foo."bar-cuz".baz': 'foo."bar-cuz".baz + 1'
}
});You can pass the whole request parameters to dynoexpr - only the expression builders will be replaced.
const params = dynoexpr({
TableName: 'Table',
Key: { HashKey: 'key' },
ReturnConsumedCapacity: 'TOTAL',
KeyCondition: {
color: 'begins_with dark',
},
});
/*
{
TableName: 'Table',
Key: { HashKey: 'key' },
ReturnConsumedCapacity: 'TOTAL',
KeyConditionExpression: '(begins_with(#n2d334799,:v1fdc3f67))',
ExpressionAttributeNames: {
'#n2d334799': 'color'
},
ExpressionAttributeValues: {
':v1fdc3f67': 'dark'
}
}
*/const params = dynoexpr({
RequestItems: {
'Table-1': {
Keys: [{ foo: 'bar' }],
Projection: ['a', 'b'],
},
},
ReturnConsumedCapacity: 'TOTAL',
});
/*
{
"RequestItems":{
"Table-1":{
"Keys": [{"foo":"bar"}],
"ProjectionExpression": "#na0f0d7ff,#ne4645342",
"ExpressionAttributeNames":{
"#na0f0d7ff": "a",
"#ne4645342": "b"
}
}
},
"ReturnConsumedCapacity": "TOTAL"
}
*/const params = dynoexpr({
TransactItems: [{
Get: {
TableName: 'Table-1',
Key: { id: 'foo' },
Projection: ['a', 'b'],
},
}],
ReturnConsumedCapacity: 'INDEXES',
});
/*
{
"TransactItems": [
{
"Get": {
"TableName": "Table-1",
"Key": { "id": "foo" },
"ProjectionExpression": "#na0f0d7ff,#ne4645342",
"ExpressionAttributeNames": {
"#na0f0d7ff":"a",
"#ne4645342":"b"
}
}
}
],
"ReturnConsumedCapacity": "INDEXES"
}
*/The resulting object is compatible with all DocumentClient requests, but if you want to be type-safe, dynoexpr accepts a generic type to be applied to the return value.
const params = dynoexpr<AWS.DocumentClient.UpdateItemInput>({
TableName: 'Table',
Key: 1,
UpdateSet: { color: 'pink' },
});Expression builder parameters
type DynamoDbPrimitive = string | number | boolean | object;
type DynamoDbValue =
| DynamoDbPrimitive
| DynamoDbPrimitive[]
| Set<DynamoDbPrimitive>;
// all attributes are optional, depending on what expression(s) are to be built
{
Condition: { [key: string]: DynamoDbValue },
ConditionLogicalOperator: 'AND' | 'OR',
KeyCondition: { [key: string]: DynamoDbValue },
KeyConditionLogicalOperator: 'AND' | 'OR',
FilterCondition: { [key: string]: DynamoDbValue },
FilterLogicalOperator: 'AND' | 'OR',
Projection: string[],
Update: { [key: string]: DynamoDbValue },
UpdateAction: 'SET' | 'ADD' | 'DELETE' | 'REMOVE',
UpdateSet: { [key: string]: DynamoDbValue },
UpdateAdd: { [key: string]: DynamoDbValue },
UpdateDelete: { [key: string]: DynamoDbValue },
UpdateRemove: { [key: string]: DynamoDbValue },
DocumentClient: AWS.DynamoDB.DocumentClient
}Parameters accepted by AWS.DynamoDB.DocumentClient
// all attributes are optional depending on the expression(s) being built
{
ConditionExpression: string,
KeyConditionExpression: string,
FilterConditionExpression: string,
ProjectionExpression: string,
UpdateExpression: string,
ExpressionAttributeNames: { [key: string]: string },
ExpressionAttributeValues: { [key: string]: string },
}MIT