Categories > Data structure > rex_nedb

Introduction

Asynchronous database.

Links

• Plugin
• ACE table
• Discussion thread

Dependence

None

Usage

Storage type

• Persistence : store database in disk

  • Set property Storage to Disk. and

  • Set Database name to a non-empty string

    • Reset to In memory mode if Database name is "", an empty string.

• In memory : store database in memory

  • Set property Storage to In memory.

Write

Insert rows by CSV

Sample capx

1. Action:Insert CSV data

   • First row : name of keys
   • Other rows : data

2. Callback

   • Trigger Condition:On update, or

   • Trigger Condition:On update error

     • `Expression:LastErrorMessage

Data type

Property Eval mode

• No : string

  • Action:Define type : define a column to be number type (Sample capx)

• Yes : parse value by eval function of javascrpt

  • number: 10
  • string: 'hi'
  • javascript function: Math.random()

  For example,

   
  xxxxxxxxxx
  Name,HP,MP
  'aaa',100,20
  'bbb',80,30
  

  will insert 2 rows.

  Error message will display on console when eval failed.

Insert rows by JSON

Sample capx

1. Action:Insert JSON data

2. Callback

   • Trigger Condition:On update, or

   • Trigger Condition:On update error

     • Expression:LastErrorMessage

Save row

Sample capx

1. prepare row

   • Save data at a specific row, i.e. pick row then update it

     • Action:Set row ID, or Action:Set row index

     • Action:Set value , to set value of index key

       • Index keys : a set of keys which the values are unique.

         • Property Index keys, or Action:Set index keys.
         • Multiple keys are separated by ,, for example

          
         xxxxxxxxxx
         UID,VarName
         

   • Other keys

     • Action:Set value

       • options: if greater , if less

     • Action:Set boolean value

     • Action:Set JSON

     • Action:Add to

2. Action:Save

   • Expression:LastSavedRowID

   • Pick row by rowID

     • Update row if found

   • Else

     • Pick row by index keys

       • Update row, if found, or
       • Insert new row

3. Callback

   • Trigger Condition:On update, or

   • Trigger Condition:On update error

     • Expression:LastErrorMessage

Update rows

Sample capx

1. Build filter and prepare row

   • Build filter

     1. Action:1. New
     2. Action:2. value compare
     3. ...

   • Prepare row

     1. Action:Set value
     2. ...

2. Action:Update queried rows

3. Callback

   • Trigger Condition:On update, or

   • Trigger Condition:On update error

     • Expression:LastErrorMessage

Remove

1. remove rows

   • Action:Remove by row ID
   • Action:Remove all
   • Action:Remove queried rows
   • Action:Remove by row index

2. Callback

   • Trigger Condition:On remove rows, or

   • Trigger Condition:On remove rows error

     • Expression:LastErrorMessage

Read

Read all rows

• Expression:AllRowsAsJSON, all rows in JSON string
• Expression:AllRowsCount

Querying

Sample capx

1. Create a new filter, or start from current filter (sample capx), if it does not create a new filter.

   • Action:1. New

2. Add conditions, or get all row, if no conditions assigned.

   • Action:2. value compare
   • Action:2. boolean value compare
   • Action:2. regex matched

3. sort

   • Action:3. order, or Condition:3. order

4. Load

   • Action:Load queried rows

5. Callback

   • Trigger Condition:On load rows, or

   • Trigger Condition:On load rows error

     • `Expression:LastErrorMessage

Read all queried rows

• Expression:QueriedRowsAsJSON, all queried rows in JSON string
• Expression:QueriedRowsCount
• Expression:QueriedSum( key )
• Expression:QueriedMin( key )
• Expression:QueriedMax( key )

Retrieve queried rows

Sample capx

Condition:For each row

• Expression:CurRowContent

  • Expression:CurRowContent, returns key-value pairs of current row in JSON string
  • Expression:CurRowContent( key ), returns the value of a specific key, or 0 if the key does not exist
  • Expression:CurRowContent( key, defaultValue ), returns the value of a specific key, or defaultValue if the key does not exist.

• Expression:CurRowIndex

Get queried row by index from 0 to Expression:QueriedRowsCount-1 (sample capx)

• Expression:Index2QueriedRowContent( index ), returns key-value pairs of the specific row in JSON string

• Expression:Index2QueriedRowContent( index, key ), returns the value of a specific key, or 0 if the key does not exist

  • Expression:Index2QueriedRowID( index ), returns rowID of the specific row

• Expression:Index2QueriedRowContent( index, key, defaultValue ), returns the value of a specific key, or defaultValue if the key does not exist.

Database reference

Sample capx

Property Database name

• Empty string "" : private database, destroyed when instance had been destroyed

• Not empty string : a global database indexed by this Database name property

  • Separate writing and reading into different database instance

Save & load

It supports official saving & loading feature when using Disk storage mode, queried rows will also be saved.

Debug panel

All rows will be shown at debug panel in JSON format.